GCinDC
100 MW
I created this poll to see if any bmsbattery chargers are still out there working... 
Have you had a BMSBattery Charger Fail?
- Thread starter GCinDC
- Start date
Stevil_Knevil
10 kW
Yes, one down out of four (that I regularly use for 12, 20 and 24S LiP0).
It was delivered with the DC polarity reversed @ the charge plug
It was delivered with the DC polarity reversed @ the charge plug
dnmun
1 PW
Stevil_Knevil said:Yes, one down out of four (that I regularly use for 12, 20 and 24S LiP0).
It was delivered with the DC polarity reversed @ the charge plug
what is the model of charger that you had with the reversed leads? did the diode blow up in the back end when you plugged it in?
Stevil_Knevil
10 kW
dnmun said:Stevil_Knevil said:Yes, one down out of four (that I regularly use for 12, 20 and 24S LiP0).
It was delivered with the DC polarity reversed @ the charge plug
what is the model of charger that you had with the reversed leads? did the diode blow up in the back end when you plugged it in?
The one that blew was an EMC-400 configured for 20S/83V, but EVERY ONE of the other 8+ chargers in that delivery had the DC plug wired in reverse! Fuse replaced and still nothing. Have not opened it yet, fully expect to find diode shrapnel..
Hey guys, Cell_Man (Paul) said all kingspan chargers are piece of crap and He got new charger called LTX charger with 3 mode switch and mentioned higher quality better than BMSBattery or Kingspan chargers.
It allows you tweak 3 different voltages by switch on the LTX charger for 60 bucks and he also mentioned it allow you lowest and high voltage. I am waiting for him to shipping the LTX charger to me. I might will provide the review once the item gets in my hand.
It allows you tweak 3 different voltages by switch on the LTX charger for 60 bucks and he also mentioned it allow you lowest and high voltage. I am waiting for him to shipping the LTX charger to me. I might will provide the review once the item gets in my hand.
dnmun
1 PW
if you can open it up and show inside that would be great so we could compare how they are built.
dnmun
1 PW
Stevil_Knevil said:dnmun said:Stevil_Knevil said:Yes, one down out of four (that I regularly use for 12, 20 and 24S LiP0).
It was delivered with the DC polarity reversed @ the charge plug
what is the model of charger that you had with the reversed leads? did the diode blow up in the back end when you plugged it in?
The one that blew was an EMC-400 configured for 20S/83V, but EVERY ONE of the other 8+ chargers in that delivery had the DC plug wired in reverse! Fuse replaced and still nothing. Have not opened it yet, fully expect to find diode shrapnel..
wow, this really is bad. 8 chargers with all of them having the leads reversed? do you still have all 8 chargers? if you open them up for pictures maybe we can see why they made such a mistake. i thought they just were sloppy about soldering the choke. this is gonna be the biggest manufacturing defect we have seen so far.
Stevil_Knevil
10 kW
dnmun said:
Yep, I have 5 of them - the blown one, and 4 that are in service and functioning well. The other 3 were for riding buddys and a client. After the 1st one went POOF, I discovered that all the charge leads were wired correctly from the charger, but inserted into the Anderson connector backwards. Super annoying, but an easy fix.
jkbrigman
10 kW
BMS Battery charger fail: 74v, 600watt self-destructed a couple days ago. Flames and all.
Bought new from BMS battery. Used it to charge my 18s15Ah pack less than 35 times.
No misuse of the charger at all: battery fine, cables fine.
Will crack it open and see if it can be fixed or not.
Bought new from BMS battery. Used it to charge my 18s15Ah pack less than 35 times.
No misuse of the charger at all: battery fine, cables fine.
Will crack it open and see if it can be fixed or not.
captain387
100 W
Voted No,
EMC-900 run at 7 amps.
Bought used (Don't know how many times it had been used prior).
Charged 12s2p 65 times
EMC-900 run at 7 amps.
Bought used (Don't know how many times it had been used prior).
Charged 12s2p 65 times
mwkeefer
1 MW
Voted Yes, One Failure Yesterday 
BMS Battery 1200W Charger - Configured to deliver 20A and cutout voltage of 49.8 or 4.15v per cell 12S. My dumb a** was trying to hook up one of those elcheapo hobbyking 130A watt meters and everything I use is polarized with 4mm plugs but I have extensions which if connected wrongly usually do nothing (to most chargers this was the first time on this one) but require a power cycle to reset.
As of now even if I apply 12v to the coils of the relay it doesn't conduct to the output... oddly enough the unit powers up fine, everything seems normal and if you listen real close when you connect a 45v pack to it there is a sound from the relay but it never conducts... an odd failure mode but I presume I can replace the burnt relay with something of equal rating and my charger will work again
If that doesn't work and the sense circuit is all fried I will try a kickstart (seperate the sense circuit, eliminate relay and hardwire the output) and see if current flows, if it does I can just replace the old sense circuit with an adaptation of Methods solid state contactor circuit to eliminate sparks (which is all the sense circuit does right).
My 400w chargers (one 12S and one 18S) are rock stars, yea they could be lighter and more adaptable (and soon may be, that's not for here but hint I just ordered a whole mess of digital pots) but they have served me for over a year faithfully and I still have one 1200W charger it just happens to be the 18S but I believe I can reconfigure it and since I use larger AH capacity 12S packs than 18S a conversion or even better a 12S mode and an 18S mode.
Forgive me, I'm trying to look at the bright side today
-Mike
BMS Battery 1200W Charger - Configured to deliver 20A and cutout voltage of 49.8 or 4.15v per cell 12S. My dumb a** was trying to hook up one of those elcheapo hobbyking 130A watt meters and everything I use is polarized with 4mm plugs but I have extensions which if connected wrongly usually do nothing (to most chargers this was the first time on this one) but require a power cycle to reset.
As of now even if I apply 12v to the coils of the relay it doesn't conduct to the output... oddly enough the unit powers up fine, everything seems normal and if you listen real close when you connect a 45v pack to it there is a sound from the relay but it never conducts... an odd failure mode but I presume I can replace the burnt relay with something of equal rating and my charger will work again
If that doesn't work and the sense circuit is all fried I will try a kickstart (seperate the sense circuit, eliminate relay and hardwire the output) and see if current flows, if it does I can just replace the old sense circuit with an adaptation of Methods solid state contactor circuit to eliminate sparks (which is all the sense circuit does right).
My 400w chargers (one 12S and one 18S) are rock stars, yea they could be lighter and more adaptable (and soon may be, that's not for here but hint I just ordered a whole mess of digital pots) but they have served me for over a year faithfully and I still have one 1200W charger it just happens to be the 18S but I believe I can reconfigure it and since I use larger AH capacity 12S packs than 18S a conversion or even better a 12S mode and an 18S mode.
Forgive me, I'm trying to look at the bright side today
-Mike
dnmun
1 PW
did you take off the end of the charger where the fan is and see if you can measure the diode to see if it is intact? did you check to see if that 12V battery on the output would put the 12V on the output caps of the charger? the kingpan charger relays have transparent case so you can see when they fail so that was why i recommended taking the black case off that one so you could see the relay inside. or just cut the entire relay off and hard wire it across on the plus side.
jkbrigman
10 kW
Can we change our answer to the poll? I've lost one BMSbattery charger but the second one is making the smell-of-death like the first one did.
dnmun
1 PW
corbinfiber just sent me his 600W BMS battery charger to fix. it was pretty easy. no lights when the little switch was turned on meant there was no excitation of the oscillator in the front end of the charger to make current flow out into the back end to create the circuit current in the backend for the 12V used to drive the little leds green and red.
so i powered it up, and double checked to see if there was not current coming from the transformer into the back end through that set of 4 little zener diodes next to the transformer that delivers the circuit current to the 12V regulator. so the problem was in the front end, in front of the transformer in the circuit.
i checked the voltage in the front end, 120V on the wires to the pcb from the plug, and i could measure the 327V DC from one end of the rectifier diode bridge to the other end so i knew that the diode was not shorted out and the capacitors across the rectifier were also not shorted since there was the full 327V present.
so then i checked the two switching transistors next to the rectifier diode which is called a totem pole transistor circuit because one of the transistors is connected to the top voltage coming off the rectifier diode and the other transistor is connected to the bottom or zero voltage of the rectifier. get it? one on top of the other? totem pole?
those switching transistors on the side there under that clamp are hard to reach in order to measure the voltage on the legs of the transistors. on this charger they are the big T0-3P package, like the TO-247 and from the front the base is on the right, collector is in the middle and the emitter is on the left.
for a normal transistor, an NPN transistor like this, the collector is at the higher voltage and the emitter is at the lowest voltage. the base rises above the emitter in order to turn the transistor on. so in this totem pole arrangement of these transistors, the collector of the high side transistor is connected to the 327V top of the rectifier, and the emitter of the bottom transistor is connected to the ground or zero volts of the rectifier diode bridge. you can follow the traces from the transistors back to the rectifier diode bridge to see that.
but in the middle, the emitter of the high side transistor is connected to the collector of the low side transistor to complete the circuit from top to bottom, and the oscillator is attached to the transistors through this middle connection. so that middle connection should be midway in voltage between the 327V and 0V, or about 164V.
on these transistors, as on all like this, the metal tab on back is connected to the collector of the transistor. the silicon die that is the transistor is bonded right onto the metal inside the package and the current flows to the tab as well as to the collector leg in the middle. this is why there is the insulating rubber piece under the tab to keep it from shorting out to the case which is grounded.
so since the collector of the low side transistor, the tab, should be at the 164V, i used my voltmeter, on the 1000V DC range, and measured the voltage on the tab of the low side transistor and it measured about 163V, maybe it was 160, forget exactly, but i knew that meant that the low side transistor was working and it was withstanding the voltage across it so it was not shorted out.
i then put the voltmeter on the tab of the high side transistor and it was only about 190V or so, so it was not able to withstand the voltage across it because it was shorted out inside. so i felt like i knew then that the problem was with this one transistor shorted out.
so i took the charger apart and used my diode tester to test the transistors individually to see if they worked. the diode tester sends out a 1A current from the red probe so that as the current flows through a diode it will show the forward bias or voltage drop across the diode made up of the base to emitter junction. the p-n junction in the npn transistor. collector base emitter. the forward bias of the emitter to base junction was about 450mV, normal.
i then used the diode tester and put the red probe on the collector and the black probe on the emitter to see if the transistor was shorted from collector to emitter and the diode tester showed open circuit so i knew that the low side transistor was not shorted.
so then i tested the high side transistor and i found that the red probe on the collector to emitter on the black probe measured about 112mV, so it was shorted and the resistance across the transistor made the meter read the 112mV as the current flowed through it from collector to emitter when no current should flow at all.
the emitter base junction also measured the same, and it also measured the same when i reversed the probes which proved that the pn diode junction of the emitter-base was shorted out so current would flow backwards now instead of being blocked by the diode junction. so i felt i had confirmed that the high side transistor was shorted and had to be replaced.
so i cut off the legs of the transistor (to make it easier to remove the transistor) and heated up the little bit of legs and solder left in the holes and pushed the last of the legs out of the holes, cleaned up the holes with solder wick so i could get the new transistor in place, then put the new transistor in the holes, leaving a little space between the bottom of the step out in the legs so there was enuff leg to allow me to do that little dog leg bend you have to make in the legs to get them to lay flat against the outer case when it is clamped down again. you will see when you get there how much to bend them over, and how far up to mount them.
then i soldered the new transistor in place, cleaned up the flux with some acetone and then alcohol to make it pretty, and reassembled the charger.
the trick in reassembling the charger is to add a little new thermal joint compound under the back of the transistors, not much, and then as you slide the pcb back into the base, make sure the holes line up for the screws from the outside into the middle of the rectifier bridge on one side, and line up the hole in the 12V regulator behind the schottky diodes on the other side. make sure the insulator is still present under the tab of the 12V regulator and make sure it has the little grommet in the middle of the hole in the TO-220 case of the 12V regulator, BEFORE you tighten either of them down. then you can put the clamps on the two npn transistors and the two schottky diodes. snug them down, not too tight, but firm against the outer case, screw the ends back on the case and then power it up.
power it up with the switch off, then when the switch is turned on the little leds on the end come on and you can measure the voltage on the output. in this case i adjusted the voltage back up to 87.7V DC for his 24S lifepo4 pack by turning the little screw on the trimpot that is next to the TL494 IC controller chip, the 16 pin IC out in the middle of the back end.
presto pringo pesta sauce and powowee, it worked, just like it once did, except for the little screw where i turned the head off with my screw gun putting it back together.
took longer to stand in line at the post office than it did to repair it. hope this makes sense and you can diagnose what is wrong with yours in the same way. i have the transistors if you wanna repair yours when it breaks so lemme know. i have all the little transistors needed for any of them from the small 240W models to the 600W like this and the big 900W ones that use the IGBTs for switching transistors. so yours can be fixed for cheap if you wanna do it.
so i powered it up, and double checked to see if there was not current coming from the transformer into the back end through that set of 4 little zener diodes next to the transformer that delivers the circuit current to the 12V regulator. so the problem was in the front end, in front of the transformer in the circuit.
i checked the voltage in the front end, 120V on the wires to the pcb from the plug, and i could measure the 327V DC from one end of the rectifier diode bridge to the other end so i knew that the diode was not shorted out and the capacitors across the rectifier were also not shorted since there was the full 327V present.
so then i checked the two switching transistors next to the rectifier diode which is called a totem pole transistor circuit because one of the transistors is connected to the top voltage coming off the rectifier diode and the other transistor is connected to the bottom or zero voltage of the rectifier. get it? one on top of the other? totem pole?
those switching transistors on the side there under that clamp are hard to reach in order to measure the voltage on the legs of the transistors. on this charger they are the big T0-3P package, like the TO-247 and from the front the base is on the right, collector is in the middle and the emitter is on the left.
for a normal transistor, an NPN transistor like this, the collector is at the higher voltage and the emitter is at the lowest voltage. the base rises above the emitter in order to turn the transistor on. so in this totem pole arrangement of these transistors, the collector of the high side transistor is connected to the 327V top of the rectifier, and the emitter of the bottom transistor is connected to the ground or zero volts of the rectifier diode bridge. you can follow the traces from the transistors back to the rectifier diode bridge to see that.
but in the middle, the emitter of the high side transistor is connected to the collector of the low side transistor to complete the circuit from top to bottom, and the oscillator is attached to the transistors through this middle connection. so that middle connection should be midway in voltage between the 327V and 0V, or about 164V.
on these transistors, as on all like this, the metal tab on back is connected to the collector of the transistor. the silicon die that is the transistor is bonded right onto the metal inside the package and the current flows to the tab as well as to the collector leg in the middle. this is why there is the insulating rubber piece under the tab to keep it from shorting out to the case which is grounded.
so since the collector of the low side transistor, the tab, should be at the 164V, i used my voltmeter, on the 1000V DC range, and measured the voltage on the tab of the low side transistor and it measured about 163V, maybe it was 160, forget exactly, but i knew that meant that the low side transistor was working and it was withstanding the voltage across it so it was not shorted out.
i then put the voltmeter on the tab of the high side transistor and it was only about 190V or so, so it was not able to withstand the voltage across it because it was shorted out inside. so i felt like i knew then that the problem was with this one transistor shorted out.
so i took the charger apart and used my diode tester to test the transistors individually to see if they worked. the diode tester sends out a 1A current from the red probe so that as the current flows through a diode it will show the forward bias or voltage drop across the diode made up of the base to emitter junction. the p-n junction in the npn transistor. collector base emitter. the forward bias of the emitter to base junction was about 450mV, normal.
i then used the diode tester and put the red probe on the collector and the black probe on the emitter to see if the transistor was shorted from collector to emitter and the diode tester showed open circuit so i knew that the low side transistor was not shorted.
so then i tested the high side transistor and i found that the red probe on the collector to emitter on the black probe measured about 112mV, so it was shorted and the resistance across the transistor made the meter read the 112mV as the current flowed through it from collector to emitter when no current should flow at all.
the emitter base junction also measured the same, and it also measured the same when i reversed the probes which proved that the pn diode junction of the emitter-base was shorted out so current would flow backwards now instead of being blocked by the diode junction. so i felt i had confirmed that the high side transistor was shorted and had to be replaced.
so i cut off the legs of the transistor (to make it easier to remove the transistor) and heated up the little bit of legs and solder left in the holes and pushed the last of the legs out of the holes, cleaned up the holes with solder wick so i could get the new transistor in place, then put the new transistor in the holes, leaving a little space between the bottom of the step out in the legs so there was enuff leg to allow me to do that little dog leg bend you have to make in the legs to get them to lay flat against the outer case when it is clamped down again. you will see when you get there how much to bend them over, and how far up to mount them.
then i soldered the new transistor in place, cleaned up the flux with some acetone and then alcohol to make it pretty, and reassembled the charger.
the trick in reassembling the charger is to add a little new thermal joint compound under the back of the transistors, not much, and then as you slide the pcb back into the base, make sure the holes line up for the screws from the outside into the middle of the rectifier bridge on one side, and line up the hole in the 12V regulator behind the schottky diodes on the other side. make sure the insulator is still present under the tab of the 12V regulator and make sure it has the little grommet in the middle of the hole in the TO-220 case of the 12V regulator, BEFORE you tighten either of them down. then you can put the clamps on the two npn transistors and the two schottky diodes. snug them down, not too tight, but firm against the outer case, screw the ends back on the case and then power it up.
power it up with the switch off, then when the switch is turned on the little leds on the end come on and you can measure the voltage on the output. in this case i adjusted the voltage back up to 87.7V DC for his 24S lifepo4 pack by turning the little screw on the trimpot that is next to the TL494 IC controller chip, the 16 pin IC out in the middle of the back end.
presto pringo pesta sauce and powowee, it worked, just like it once did, except for the little screw where i turned the head off with my screw gun putting it back together.
took longer to stand in line at the post office than it did to repair it. hope this makes sense and you can diagnose what is wrong with yours in the same way. i have the transistors if you wanna repair yours when it breaks so lemme know. i have all the little transistors needed for any of them from the small 240W models to the 600W like this and the big 900W ones that use the IGBTs for switching transistors. so yours can be fixed for cheap if you wanna do it.
cwah
100 MW
I often have charger that fail, if only I have someone I can send all my broken electronic part in europe... :lol:
captain387
100 W
Thank you dnmun, that was a nice and thorough trouble shooting procedure. I am sure that I would be able to make my way through the diagnostic steps when my charger fails in this way.
Now as they always say, a picture,,,,, or video :wink: is a 1000 words/definitions. As I am not too familiar with "all" of the components you have described I would search for each item online to make sure I am testing the right component(Yes I know this is called learning) within the charger. Now if you didn't want to make any more money fixing these chargers, a video of trouble shooting the next charger would be very helpful to the semi electrical crowd.
Thanks again for your time!
Also I think that this poll could be revised as eventually every charger, good and bad will fail sooner or later.
Suggested topics, not my experience
Yes I have had one fail it lasted 1 year, 2 year...
Yes I have had one fail, my fault
Yes I have had one fail, manufacturer fault
Yes I have had one fail but it has been fixed by dnmun
Done with my 7 am ramblings
Now as they always say, a picture,,,,, or video :wink: is a 1000 words/definitions. As I am not too familiar with "all" of the components you have described I would search for each item online to make sure I am testing the right component(Yes I know this is called learning) within the charger. Now if you didn't want to make any more money fixing these chargers, a video of trouble shooting the next charger would be very helpful to the semi electrical crowd.
Thanks again for your time!
Also I think that this poll could be revised as eventually every charger, good and bad will fail sooner or later.
Suggested topics, not my experience
Yes I have had one fail it lasted 1 year, 2 year...
Yes I have had one fail, my fault
Yes I have had one fail, manufacturer fault
Yes I have had one fail but it has been fixed by dnmun
Done with my 7 am ramblings
dnmun
1 PW
if i did a video, how would that make anyone think? it would just be more video, and no mental exercise is involved. i do not know that much about them, i just decided to figure it out in order to educate myself about electronics. that is why i spend so much time trying to get people to analyze their own equipment, to try to get people to learn how to think. but i know people prefer videos, because they don't have to think, to figure out what i am talking about by looking at their charger.
go dig out your dead charger, open it up and start looking inside at the various parts. there are smart people around who are EEs who post on here and they could explain it more intelligently, i just hack at it the same way i had to learn how to repair cars.
but i got to thinking it would help if i explained kinda in general terms what the power supply is doing. kinda like if people had a simple view of the overall way it worked it would make more sense.
but first, when looking at the charger, do the obvious things first. make sure the fuses are working, then see if there is 120V(or240 in europe and oz), are the leds lit but no output voltage?>>>maybe the fuse on the output is blown or the cord or plug has a broken wire or connector, is there a relay on the output that requires you to plug in the battery to turn on the output ?(i have seen chargers that were returned to the seller with complaints that there is no output because they measured it without connecting the battery, perfectly good charger, returned for refund).
these chargers, kingpan and EMC models are essentially identical, down to the resistor and capacitor values and the pcb layout is almost identical, but different enuff it does not violate trademarks i guess.
when you look inside you see there are two sections, one where the AC voltage come in and the other end where the DC current goes out. that big transformer is in the middle. so there is a "front end" before the transformer and "back end" where the current from the output of the transformer goes out to the battery.
the front end has the rectifier diode bridge which converts the AC to a stabilized high voltage DC signal that is floating on the that input capacitor, with ripples on top of it. that is the 320-340V you measure across the legs of the rectifier bridge. that 340V is then standing across the two totem pole npn (high voltage, high current) transistors. these two transistor are driven by an oscillator circuit that comes from that little transformer in the back end which itself is driven by the big 16 pin TL494 Integrated Circuit (IC) in the back end through the little transistors you see between the IC and the little transformer.
so the totem pole acts to push and pull current, at high voltage, through that big transformer. that current in the 'primary' windings of the transformer excites a current in the 'secondary' windings of the big transformer and that current goes out of the secondary into the back end of the charger.
the amount of current coming out of the transformer is dependent on how much current is pushed and pulled by the two totem pole transistors in the oscillator circuit of the front end. the TL494 can tell how much current it needs by feedback on it's input pins so it knows how much to push the little transformer to make it push the totem pole transistors in the front end to get the amount of current out of the transformer it needs to push up the voltage on the output.
so that is how it works, the push-pull circuit in the front end makes the transformer deliver current to the back end, and the TL494 maintains control over it. provides the feedback to keep it from blowing up as it would naturally without the feedback.
but there are two sets of windings in the secondary. one set delivers the current to the output through the big schottky diodes on the side there which convert it from AC back to a DC signal that is now floating on the output capacitor after some of the DC ripple is ironed out by that big toroid, called a choke, between the diodes and the capacitor/output.
the other set of windings in the back end are small and do not handle very much current at all like the main secondary windings do. this second set of windings is how the circuit current is generated in the back end to run the little electrical components and fan in the back end. this second set of windings delivers the current through that set of four little zener diodes sitting together in a row next to the transformer.
the four diodes make a rectifier diode bridge just like the one on the front end, just smaller and low voltage. you can see there is a little 35V capacitor sitting on the output from those diodes as it goes over to the input of the 12V regulator in a TO-220 package usually clamped to the case for heat sinking.
the output from the 12V regulator is used to supply current to the transistors, ICs and leds in the back end along with providing the current to drive the fan.
by now you will have seen all the components that do real work to make the current in the back end. the other stuff in the back end like the current sensing loop and the op amp that detects when the current has dropped to a low enuff level to switch the charger over to Constant Voltage (CV) at a point very close to the final voltage. that's what all that little stuff in the back end does, it doesn't make the current that goes to the battery.
so there are numerous and unknown permutations that can happen to prevent it from working to deliver current to the output, and limiting it to a few pictures in a video would limit what you have to consider has happened to cause it to fail. so this is where you have to use the only human function we have that separates us from bacteria, your mental faculties to analyze what information you can create by examination. this is why i find thinking enjoyable and some do not and prefer videos.
in most cases the failure will be obvious, a bulging capacitor, a black smoky spray under a transistor or loose wires even should draw you attention. but it can be systematically analyzed by starting with the fundamentals of the circuit and testing with the voltmeter to see if there is voltage present at various points in the circuit either in the front end or back end.
in the case of corbin's charger i noted there were no leds lit in the back end so the first thing i tested with the voltmeter was the voltage on the output of the 4 little zener diodes which supply the circuit current to the back end. usually about 20V DC on the end of the zener diode, but there was no voltage, so i knew that the transformer was not being excited by the oscillator driving current in the front end, (or the transformer could be shorted, or the windings open for that set of secondary windings).
so i looked into the front end, measured the voltage where the AC comes onto the board (use the high voltage AC on the meter), it was ok, then i checked the high voltage from one end of the rectifier bridge to the other end (1000V DC scale) and measured the 327V DC, ok.
so i knew now that there was voltage present on the totem pole transistors and the next thing to do was to measure the voltage of the transistors that are driven from that 327V. i expected the voltage to be evenly split between them. and i knew that the collector of the lower transistor (the high side of the bottom transistor) is connected to the emitter of the upper totem pole transistor (low side of the upper) so if i could measure the voltage at that spot in the middle i figure i would learn something.
but you cannot reach the legs of the totem pole transistors because they are so far down and underneath that clamp which is ground so if you short the transistor legs to the clamp with your voltmeter probe it will blow up the transistor and make a mess of your probe. so that is why i used the fact that the collector of the transistor is connected to the tab on each transistor.
so i put the voltmeter probe on the tab of the lower transistor (because that is the middle where the emitter of the high side and the collector of the low side split the voltage) and measured the 160V DC (using the 1000V DC scale on the meter). then i measured the voltage of the tab on the high side transistor and it was only about 190V and not the 327V which i expected from the voltage on the rectifier, so that was the clear indication that the transistor was shorted and the current was flowing though the transistor when it should be turned off and the voltage drop across the shorted transistor added a little voltage above the tab of the lower transistor.
so that was enuff for me to take it apart and remove the transistor and replace it with another one to repair it. but to be certain, after i took it apart, i measured the pn diode junction of base to emitter of both transistors and the lower one showed the 450mV of a normal pn junction and the high side transistor showed 112mV of a shorted junction. also by putting the red probe on the collector(middle leg) and the black probe on the emitter(left leg) the diode tester could not push current through the good transistor so it read open circuit but when i put the diode tester across the collector-emitter of the high side transistor it measured the same 112mV of the short. so it was confirmed that the high side transistor was bad, cut the legs off, unsoldered the little bit of leg left and soldered in the new one leaving the space on the legs so i could bend it to the little dog leg to make it fit flat against the side of the case when it was clamped later.
it could have been different and the low side transistor could have failed and in that case i would have expected the tab of that low side transistor (the collector connected to the emitter in the middle of the totem pole) to be very low, say around 20-30V like the other one i just discussed, and if it was low then you would be able to assume the low side switching transistor had failed and need to be replaced.
but measure both to be sure you know whether only one or both of them failed before you take it apart. test them both with the diode tester when you get it apart.
there are other ways the chargers fail too. often the schottky diodes will just become exhausted from running so hot for so long they finally go out. in that case you would have the leds lit in the output because the front end is acting normal but there is no current going through the diodes. to test for that you use the DC scale and put the black probe on ground in the output, the - spot or you can put the probe on the wire loop used for the current sensor since it is easy to access and is also at ground.
then you measure the voltage on the big wide trace coming off the schottky diodes. if there is no voltage then you need to test the schottky diodes with the diode tester.
if there is voltage coming off the schottky diodes then the next thing to test is the big toroid since sometimes it will get so hot it melts the solder out of the connection or can even burn the trace off, but that stuff is usually obvious.
the biggest problem for these chargers in the back end is where the choke is so hot that it melts the varnish on the pcb that insulates the trace coming from the 4 zener diodes for the circuit current and running over to the 12V regulator on the side.
that trace runs directly underneath the choke and i have seen several instances where the high voltage of the output going through the choke is shorted to the lower 20V on that trace running to the 12V regulator and that high voltage is very very hard on the electrical components in the back end.
you will see the blown up (by high voltage of the output) small capacitors and sometimes other parts but when that happens it usually stops working immediately but sometimes the short can be really bad, and difficult to repair because the little caps are hard to unsolder and replace.
the other problems i have seen involve the charger basically running full out with high high voltage appearing on the output, like 112V or so and that will blow up the output caps. this is caused by failure of the feedback mechanism the TL494 should provide and is something i have had trouble identifying. i have even replaced all the electrical components in the back end of a charger like this and it still was not functional and finally blew up the output caps so much i gave up.
i had the top off one time and the output caps went off like a roman candle, shooting pretty sparks and smoke up into the sky. another time it happened inside the charger with the cover on and made a huge black smoke cloud inside above the output cap.
good luck, go look at it and start figuring out what you are looking at, then think of how to test it for what could be wrong. maybe i can help, maybe not. make a video if you wanna to show how far you got and why you did it for us to comment on.
if you wanna see a schematic of the charger circuit you can look at this work by albert vandalen, thanks again so much to albert:
http://www.avdweb.nl/solar-bike/electronics/portable-lightweight-lifepo4-ebike-battery-charger-800g.html
go dig out your dead charger, open it up and start looking inside at the various parts. there are smart people around who are EEs who post on here and they could explain it more intelligently, i just hack at it the same way i had to learn how to repair cars.
but i got to thinking it would help if i explained kinda in general terms what the power supply is doing. kinda like if people had a simple view of the overall way it worked it would make more sense.
but first, when looking at the charger, do the obvious things first. make sure the fuses are working, then see if there is 120V(or240 in europe and oz), are the leds lit but no output voltage?>>>maybe the fuse on the output is blown or the cord or plug has a broken wire or connector, is there a relay on the output that requires you to plug in the battery to turn on the output ?(i have seen chargers that were returned to the seller with complaints that there is no output because they measured it without connecting the battery, perfectly good charger, returned for refund).
these chargers, kingpan and EMC models are essentially identical, down to the resistor and capacitor values and the pcb layout is almost identical, but different enuff it does not violate trademarks i guess.
when you look inside you see there are two sections, one where the AC voltage come in and the other end where the DC current goes out. that big transformer is in the middle. so there is a "front end" before the transformer and "back end" where the current from the output of the transformer goes out to the battery.
the front end has the rectifier diode bridge which converts the AC to a stabilized high voltage DC signal that is floating on the that input capacitor, with ripples on top of it. that is the 320-340V you measure across the legs of the rectifier bridge. that 340V is then standing across the two totem pole npn (high voltage, high current) transistors. these two transistor are driven by an oscillator circuit that comes from that little transformer in the back end which itself is driven by the big 16 pin TL494 Integrated Circuit (IC) in the back end through the little transistors you see between the IC and the little transformer.
so the totem pole acts to push and pull current, at high voltage, through that big transformer. that current in the 'primary' windings of the transformer excites a current in the 'secondary' windings of the big transformer and that current goes out of the secondary into the back end of the charger.
the amount of current coming out of the transformer is dependent on how much current is pushed and pulled by the two totem pole transistors in the oscillator circuit of the front end. the TL494 can tell how much current it needs by feedback on it's input pins so it knows how much to push the little transformer to make it push the totem pole transistors in the front end to get the amount of current out of the transformer it needs to push up the voltage on the output.
so that is how it works, the push-pull circuit in the front end makes the transformer deliver current to the back end, and the TL494 maintains control over it. provides the feedback to keep it from blowing up as it would naturally without the feedback.
but there are two sets of windings in the secondary. one set delivers the current to the output through the big schottky diodes on the side there which convert it from AC back to a DC signal that is now floating on the output capacitor after some of the DC ripple is ironed out by that big toroid, called a choke, between the diodes and the capacitor/output.
the other set of windings in the back end are small and do not handle very much current at all like the main secondary windings do. this second set of windings is how the circuit current is generated in the back end to run the little electrical components and fan in the back end. this second set of windings delivers the current through that set of four little zener diodes sitting together in a row next to the transformer.
the four diodes make a rectifier diode bridge just like the one on the front end, just smaller and low voltage. you can see there is a little 35V capacitor sitting on the output from those diodes as it goes over to the input of the 12V regulator in a TO-220 package usually clamped to the case for heat sinking.
the output from the 12V regulator is used to supply current to the transistors, ICs and leds in the back end along with providing the current to drive the fan.
by now you will have seen all the components that do real work to make the current in the back end. the other stuff in the back end like the current sensing loop and the op amp that detects when the current has dropped to a low enuff level to switch the charger over to Constant Voltage (CV) at a point very close to the final voltage. that's what all that little stuff in the back end does, it doesn't make the current that goes to the battery.
so there are numerous and unknown permutations that can happen to prevent it from working to deliver current to the output, and limiting it to a few pictures in a video would limit what you have to consider has happened to cause it to fail. so this is where you have to use the only human function we have that separates us from bacteria, your mental faculties to analyze what information you can create by examination. this is why i find thinking enjoyable and some do not and prefer videos.
in most cases the failure will be obvious, a bulging capacitor, a black smoky spray under a transistor or loose wires even should draw you attention. but it can be systematically analyzed by starting with the fundamentals of the circuit and testing with the voltmeter to see if there is voltage present at various points in the circuit either in the front end or back end.
in the case of corbin's charger i noted there were no leds lit in the back end so the first thing i tested with the voltmeter was the voltage on the output of the 4 little zener diodes which supply the circuit current to the back end. usually about 20V DC on the end of the zener diode, but there was no voltage, so i knew that the transformer was not being excited by the oscillator driving current in the front end, (or the transformer could be shorted, or the windings open for that set of secondary windings).
so i looked into the front end, measured the voltage where the AC comes onto the board (use the high voltage AC on the meter), it was ok, then i checked the high voltage from one end of the rectifier bridge to the other end (1000V DC scale) and measured the 327V DC, ok.
so i knew now that there was voltage present on the totem pole transistors and the next thing to do was to measure the voltage of the transistors that are driven from that 327V. i expected the voltage to be evenly split between them. and i knew that the collector of the lower transistor (the high side of the bottom transistor) is connected to the emitter of the upper totem pole transistor (low side of the upper) so if i could measure the voltage at that spot in the middle i figure i would learn something.
but you cannot reach the legs of the totem pole transistors because they are so far down and underneath that clamp which is ground so if you short the transistor legs to the clamp with your voltmeter probe it will blow up the transistor and make a mess of your probe. so that is why i used the fact that the collector of the transistor is connected to the tab on each transistor.
so i put the voltmeter probe on the tab of the lower transistor (because that is the middle where the emitter of the high side and the collector of the low side split the voltage) and measured the 160V DC (using the 1000V DC scale on the meter). then i measured the voltage of the tab on the high side transistor and it was only about 190V and not the 327V which i expected from the voltage on the rectifier, so that was the clear indication that the transistor was shorted and the current was flowing though the transistor when it should be turned off and the voltage drop across the shorted transistor added a little voltage above the tab of the lower transistor.
so that was enuff for me to take it apart and remove the transistor and replace it with another one to repair it. but to be certain, after i took it apart, i measured the pn diode junction of base to emitter of both transistors and the lower one showed the 450mV of a normal pn junction and the high side transistor showed 112mV of a shorted junction. also by putting the red probe on the collector(middle leg) and the black probe on the emitter(left leg) the diode tester could not push current through the good transistor so it read open circuit but when i put the diode tester across the collector-emitter of the high side transistor it measured the same 112mV of the short. so it was confirmed that the high side transistor was bad, cut the legs off, unsoldered the little bit of leg left and soldered in the new one leaving the space on the legs so i could bend it to the little dog leg to make it fit flat against the side of the case when it was clamped later.
it could have been different and the low side transistor could have failed and in that case i would have expected the tab of that low side transistor (the collector connected to the emitter in the middle of the totem pole) to be very low, say around 20-30V like the other one i just discussed, and if it was low then you would be able to assume the low side switching transistor had failed and need to be replaced.
but measure both to be sure you know whether only one or both of them failed before you take it apart. test them both with the diode tester when you get it apart.
there are other ways the chargers fail too. often the schottky diodes will just become exhausted from running so hot for so long they finally go out. in that case you would have the leds lit in the output because the front end is acting normal but there is no current going through the diodes. to test for that you use the DC scale and put the black probe on ground in the output, the - spot or you can put the probe on the wire loop used for the current sensor since it is easy to access and is also at ground.
then you measure the voltage on the big wide trace coming off the schottky diodes. if there is no voltage then you need to test the schottky diodes with the diode tester.
if there is voltage coming off the schottky diodes then the next thing to test is the big toroid since sometimes it will get so hot it melts the solder out of the connection or can even burn the trace off, but that stuff is usually obvious.
the biggest problem for these chargers in the back end is where the choke is so hot that it melts the varnish on the pcb that insulates the trace coming from the 4 zener diodes for the circuit current and running over to the 12V regulator on the side.
that trace runs directly underneath the choke and i have seen several instances where the high voltage of the output going through the choke is shorted to the lower 20V on that trace running to the 12V regulator and that high voltage is very very hard on the electrical components in the back end.
you will see the blown up (by high voltage of the output) small capacitors and sometimes other parts but when that happens it usually stops working immediately but sometimes the short can be really bad, and difficult to repair because the little caps are hard to unsolder and replace.
the other problems i have seen involve the charger basically running full out with high high voltage appearing on the output, like 112V or so and that will blow up the output caps. this is caused by failure of the feedback mechanism the TL494 should provide and is something i have had trouble identifying. i have even replaced all the electrical components in the back end of a charger like this and it still was not functional and finally blew up the output caps so much i gave up.
i had the top off one time and the output caps went off like a roman candle, shooting pretty sparks and smoke up into the sky. another time it happened inside the charger with the cover on and made a huge black smoke cloud inside above the output cap.
good luck, go look at it and start figuring out what you are looking at, then think of how to test it for what could be wrong. maybe i can help, maybe not. make a video if you wanna to show how far you got and why you did it for us to comment on.
if you wanna see a schematic of the charger circuit you can look at this work by albert vandalen, thanks again so much to albert:
http://www.avdweb.nl/solar-bike/electronics/portable-lightweight-lifepo4-ebike-battery-charger-800g.html
www.recumbents.com
10 kW
Need a survey option "Yes but I fixed it".
Mine had a crappy fuse holder that failed and I replaced it. And the AC power cord was some funky stiff plastic thing, so I replaced that.
Later I made the mistake of connecting the charger to the battery before the AC power which fortunately just blew a fuse.
I have the 600W version. and it's still working fine otherwise to bulk charge my 12S LiPo.
-Warren.
Mine had a crappy fuse holder that failed and I replaced it. And the AC power cord was some funky stiff plastic thing, so I replaced that.
Later I made the mistake of connecting the charger to the battery before the AC power which fortunately just blew a fuse.
I have the 600W version. and it's still working fine otherwise to bulk charge my 12S LiPo.
-Warren.
captain387
100 W
Thanks Dnmun
The expanded explanation is definitely helpful to myself and I am sure others.
Luckily for me the only charger I have owned which is the EMC 900 is working perfectly.
I have been running it at less than half(7 amps 48v system) of its rated capacity so I am sure that is why it has lasted or the luck of the draw is more likely.
When I do have a problem I will follow your steps, even if there is an obvious blown cap or whatever as we all know that there can be multiple issues.
I may try and build the anti spark circuit that is advised in the link you posted as it may be easier on the charger as well as the connectors.
Have you built one for your chargers?
As far as cars go, I've been pretty happy with my trouble shooting,, unfortunately after a garage part swapped prior to diagnosis.
Fuel pump was replaced didn't fix problem $300. Went home searched issue, spent 20 minutes replacing solder on fuel pump relay due to "Cracking" fixed
Driving light relay re-solder to fix lights not coming on
Canadian tire said I had a bad battery when car wouldn't start even with it cranking the engine over. I knew the battery was fine searched online replaced distributor cap to fix problem.
Now I have given up on the ac/heater control circuit board, sporadic led lights turning on and off. When you you flex the control panel the lights come on sometimes. Searched online, soldered jumpers, re-melted a lot of solder joints, ran through with volt meter but there are a million little traces, some people say bad through holes, broken traces etc. Can't win them all
The expanded explanation is definitely helpful to myself and I am sure others.
Luckily for me the only charger I have owned which is the EMC 900 is working perfectly.
I have been running it at less than half(7 amps 48v system) of its rated capacity so I am sure that is why it has lasted
or the luck of the draw is more likely.When I do have a problem I will follow your steps, even if there is an obvious blown cap or whatever as we all know that there can be multiple issues.
I may try and build the anti spark circuit that is advised in the link you posted as it may be easier on the charger as well as the connectors.
Have you built one for your chargers?
As far as cars go, I've been pretty happy with my trouble shooting,, unfortunately after a garage part swapped prior to diagnosis.
Fuel pump was replaced didn't fix problem $300. Went home searched issue, spent 20 minutes replacing solder on fuel pump relay due to "Cracking" fixed
Driving light relay re-solder to fix lights not coming on
Canadian tire said I had a bad battery when car wouldn't start even with it cranking the engine over. I knew the battery was fine searched online replaced distributor cap to fix problem.
Now I have given up on the ac/heater control circuit board, sporadic led lights turning on and off. When you you flex the control panel the lights come on sometimes. Searched online, soldered jumpers, re-melted a lot of solder joints, ran through with volt meter but there are a million little traces, some people say bad through holes, broken traces etc. Can't win them all
dnmun
1 PW
i had the fuel pump relay problem too. i had to resolder the cold solder joints that caused the relay to be intermittent just like you. but initially i thought it was a bad starter so i took the starter apart thinking i could find it, nope. then even after i fix the fuel pump relay it was still intermittent because there was an interlock switch on the clutch. something i had never seen before and took forever to figure out. damnit.
i consider the EMC-900 to be superior to the other chargers because the IGBT switching transistors are almost unbreakable imo. that is what i find dies the most on the smaller chargers. especially the little 240W models. those are the small TO-220 cased FJP13009 npn switching transistors. but the bigger one die too from having the switching transistors go out. i have almost 8-10 small chargers open now waiting for me to take the time to replace the transistors.
but i enjoy fixing things, since i was a kid. it worked for me when i had to manage development of new process steps and maintaining the etch and deposition steps when we developed the nMOS-3 process and built the first 32 bit microprocessor back in 1981. and it now extends even to big projects like houses and large concrete pours. i consider the 35 yards of concrete i have poured here to be the pinnacle of my learned skills. stuff like wiring and plumbing or insulating and windows and sheet rocking don't ever measure up to roofing and laying out grade and forms for the concrete pour, then packing fill and pouring concrete. you cannot imagine the sickening feeling of impending doom when the ready mix truck pulls up and you have to pour 8 yards of concrete. too much stress.
so it has gotta be the greatest feeling of accomplishment looking at my driveway apron with the 4 charging spots. it will be there for another 150 years, charging thousands of cars over the next century. but now i am getting too old to do it anymore so diddling with these chargers and batteries is all i can do anymore.
i consider the EMC-900 to be superior to the other chargers because the IGBT switching transistors are almost unbreakable imo. that is what i find dies the most on the smaller chargers. especially the little 240W models. those are the small TO-220 cased FJP13009 npn switching transistors. but the bigger one die too from having the switching transistors go out. i have almost 8-10 small chargers open now waiting for me to take the time to replace the transistors.
but i enjoy fixing things, since i was a kid. it worked for me when i had to manage development of new process steps and maintaining the etch and deposition steps when we developed the nMOS-3 process and built the first 32 bit microprocessor back in 1981. and it now extends even to big projects like houses and large concrete pours. i consider the 35 yards of concrete i have poured here to be the pinnacle of my learned skills. stuff like wiring and plumbing or insulating and windows and sheet rocking don't ever measure up to roofing and laying out grade and forms for the concrete pour, then packing fill and pouring concrete. you cannot imagine the sickening feeling of impending doom when the ready mix truck pulls up and you have to pour 8 yards of concrete. too much stress.
so it has gotta be the greatest feeling of accomplishment looking at my driveway apron with the 4 charging spots. it will be there for another 150 years, charging thousands of cars over the next century. but now i am getting too old to do it anymore so diddling with these chargers and batteries is all i can do anymore.
Just wanted to say how grateful I am to dnmun for posting the inner workings of these chargers I sat with the schematic and went over it as I read your explanation of the circuit. I understood the properties of each of the individual electrical componets but did not have much of a holistic understanding of circuits when these components are grouped together. Very educational with especially good explanations that anyone can understand. Once again thankyou.
jumpjack
100 W
- Joined
- Apr 11, 2011
- Messages
- 197
Very interesting thread.
Around a dozen of my kingpan chargers (yes, a dozen, in 3 years) failed; 90% of them in same way: coil overheating, surrounding capacitors blowing up:
http://jumpjack.wordpress.com/2012/03/20/diario-elettrico-36-viaggio-nel-caricabatterie/
http://jumpjack.wordpress.com/2012/03/26/diario-elettrico-41-ancora-sul-caricabatterie/
Any idea which could be the cause?
They start overheating around 4-5 months after purchasing.
They're rated 67.2V/3A and used for a 16S6P li-ion 60V/24Ah battery. Measured output current is <2A also during overheating. I never tuned any trimmer, but I'd like to figure ot which one to adjust to reduce current.
I created a post on my blog about a very interesting schematic I found for Kingpan chargers:
http://jumpjack.wordpress.com/2014/05/23/schema-elettrico-caricabatterie-li-ion-kingpan-forse/
Around a dozen of my kingpan chargers (yes, a dozen, in 3 years) failed; 90% of them in same way: coil overheating, surrounding capacitors blowing up:
http://jumpjack.wordpress.com/2012/03/20/diario-elettrico-36-viaggio-nel-caricabatterie/
http://jumpjack.wordpress.com/2012/03/26/diario-elettrico-41-ancora-sul-caricabatterie/
Any idea which could be the cause?
They start overheating around 4-5 months after purchasing.
They're rated 67.2V/3A and used for a 16S6P li-ion 60V/24Ah battery. Measured output current is <2A also during overheating. I never tuned any trimmer, but I'd like to figure ot which one to adjust to reduce current.
I created a post on my blog about a very interesting schematic I found for Kingpan chargers:
http://jumpjack.wordpress.com/2014/05/23/schema-elettrico-caricabatterie-li-ion-kingpan-forse/
