BMS Battery Alloy Shell Charger Problems

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rui_fujino
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BMS Battery Alloy Shell Charger Problems

Post by rui_fujino » Apr 01, 2012 12:24 pm

Hi, I've noticed so many of us faces faulty BMS Alloy shell charger thus I'm dedicating this thread for tips and Q&A for problems people has faced.
I have broken 2 of them in the past already (2years) and I really dont like them since for some of us they NEVER breaks.

Now, If anyone had problems with BMS Chargers and HAVE been able to fix them could you let us know how?
or
If anyone has upgraded them and are familiar with their common problems could you also post them here please.

I hope this thread will become useful! :wink:
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Re: BMS Battery Alloy Shell Charger Problems

Post by eva-michael » Apr 05, 2012 2:12 am

Alloy shell is only the appearance. KP charger is one of the manufactuer who use this appearance very early. And as I know, right now there are not less than 8 manufacturers are supply similar Alloy Shell Chargers. They are not same quality as the circuit design, electronic component,.....are more or less different.
For high power rate charger, one of the reason is overheating which make the electronic component of charger get burn.
Anyway, I think the most important thing is get a product with warranty.

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Re: BMS Battery Alloy Shell Charger Problems

Post by grindz145 » Apr 05, 2012 7:53 am

In the couple that I have, the pots drift like crazy. If there is any vibration at all, the charging voltage can go way up or down. I need to replace the pots with something less junky.

I know GCinDC just blew his up last week. looked like a bad cap.

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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 05, 2012 8:05 am

how did your charger die? usually they fail when the ICL blows up.

did you take either of the 2 chargers you said had died apart to see what happened?

we have been able to fix most of them for a few cents each.

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Re: BMS Battery Alloy Shell Charger Problems

Post by miuan » Apr 05, 2012 9:37 am

I've had two of them fail.
The 240W unit appears to be dead on arrival, only the green light is lit, and no red light. It stays cool. Output is zero volts. It looks mint inside, no loose parts either.
The 900W made quite a lot of smoke last time I used it but it still worked. Haven't used it ever since, I need to have a look what's broken inside.

As for Evassemble: I'll never shop with you unless the calculator yields a much more sensible shipping cost for my location. 150 USD for a 3.5kg item is ridiculous. Also, is the speed specified for BPM motors at 36V or 48V? Come on Michael, your sig says you can do better, prove it!

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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 05, 2012 10:06 am

can you measure the voltage inside the charger on the front end and the back end? pictures will help to diagnose it.

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Re: BMS Battery Alloy Shell Charger Problems

Post by rui_fujino » Apr 05, 2012 10:12 am

dnmun wrote:how did your charger die? usually they fail when the ICL blows up.

did you take either of the 2 chargers you said had died apart to see what happened?

we have been able to fix most of them for a few cents each.
for mine, nothing blew up unlike everyone else..(if it did, it would make my life easier), First one came broken and second one just died after 2use...I guess something must have became loose...(they are all 600w)
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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 05, 2012 11:01 am

you asked at the beginning of your thread how to fix them. we have been able to help a lot of people fix their chargers but you have to open it up and measure the voltages as they go from the front end to the back end and include pictures so we can offer advice. we should be able to get them both working again.

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Re: BMS Battery Alloy Shell Charger Problems

Post by rui_fujino » Apr 05, 2012 4:00 pm

dnmun wrote:you asked at the beginning of your thread how to fix them. we have been able to help a lot of people fix their chargers but you have to open it up and measure the voltages as they go from the front end to the back end and include pictures so we can offer advice. we should be able to get them both working again.
I have no idea what exactly the problem is but as far as i know nothing has blown(visibly) and when i plug in the charger to the AC it makes electronic buzzing noise.
also, compared to other user's PCB my multi-colored LED has gone brown... :? (they still light up)
I will get some readings on output voltage later on but if you could give me anything to measure I'll test it and get the result back asap.

Thanks for the help! :)
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Project 3: DOPPELGANGER d2 Visceral
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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 05, 2012 4:19 pm

ok buzzing. you will notice that the Switch Mode Power Supply SMPS has a front end and a back end, separated by the transformer. there is high voltage AC in the front end and it will sting if you let it touch you but if you can find where the output from the rectifier bridge is applied across the terminal of the capacitor on the front end, there should be a DC voltage with AC ripple on it.

that DC is switched at high frequency through the transformer by the power mosfet you will see in a heat sink on the side. when the current is switched through the transformer, it induces current in the output that goes to the back end. should be about 5 legs or maybe 6, some to the output and some supply current to the op amps and other parts.

the pulsing DC output of the transformer into the back end goes through a schottky diode into the output section which has the output cap on it and that cap smooths out the ripples in the output voltage from the switching. so just look and familiarize yourself with how it goes from front to back and see if you can measure the voltages on those traces. the wire shunt is where the delta voltage is generated to be used as feedback to the op amp that controls the amount of current that goes to the output. so you will find a trace from the high side of the shunt that goes over to the op amps. but if it is buzzing and you don't have any voltage in the back end then we will look more at the transformer leads. BOL, dm

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Re: BMS Battery Alloy Shell Charger Problems

Post by eva-michael » Apr 05, 2012 10:08 pm

miuan wrote:I've had two of them fail.
The 240W unit appears to be dead on arrival, only the green light is lit, and no red light. It stays cool. Output is zero volts. It looks mint inside, no loose parts either.
The 900W made quite a lot of smoke last time I used it but it still worked. Haven't used it ever since, I need to have a look what's broken inside.

As for Evassemble: I'll never shop with you unless the calculator yields a much more sensible shipping cost for my location. 150 USD for a 3.5kg item is ridiculous. Also, is the speed specified for BPM motors at 36V or 48V? Come on Michael, your sig says you can do better, prove it!
The shipping cost is for batteries cargo in our website. 150USD almost 20KG batteries cargo.
The shipping to North America, European Union countries, Japan, Korea are real offer from FEDEX and DHL(We take the lower one of them to our shipping system). Shipping of other destinations always changes. It will be better that we can check shipping for those destinations after email us.
3.5KG is 60USD to North America. Most of other countries are similar.
For example: 38120S with holder and connector together is 15.5USD in EVAssemble, 72pcs which is 24KG will take 207USD to North America and most of European Union countries. Shipping of 16KG = Shipping of 20KG. 17 18 19KG shipping cost is a little higher than 20KG according to dhl and fedex. quite odd but it's true.
Whe order BPM from us, you can select 36v or 48v in the page bpm500W and bpm350W. It's quite convenience.
As we always notice our customer:
Order placing will be available both via website or email us ev.assemble@gmail.com. For any inquiry or custom-designed order, pls give us contact. We will response asap within 24hours. Online shipping calculator is on batteries basic. We have cheaper delivery offer for not battery items. Pls directly contact us.

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Re: BMS Battery Alloy Shell Charger Problems

Post by rui_fujino » Apr 06, 2012 11:19 am

dnmun wrote:ok buzzing. you will notice that the Switch Mode Power Supply SMPS has a front end and a back end, separated by the transformer. there is high voltage AC in the front end and it will sting if you let it touch you but if you can find where the output from the rectifier bridge is applied across the terminal of the capacitor on the front end, there should be a DC voltage with AC ripple on it.

that DC is switched at high frequency through the transformer by the power mosfet you will see in a heat sink on the side. when the current is switched through the transformer, it induces current in the output that goes to the back end. should be about 5 legs or maybe 6, some to the output and some supply current to the op amps and other parts.

the pulsing DC output of the transformer into the back end goes through a schottky diode into the output section which has the output cap on it and that cap smooths out the ripples in the output voltage from the switching. so just look and familiarize yourself with how it goes from front to back and see if you can measure the voltages on those traces. the wire shunt is where the delta voltage is generated to be used as feedback to the op amp that controls the amount of current that goes to the output. so you will find a trace from the high side of the shunt that goes over to the op amps. but if it is buzzing and you don't have any voltage in the back end then we will look more at the transformer leads. BOL, dm
okay I've done some tracing and gone through the circuit...now The output voltage of the charger shows 82.7v so how come it doesnt charge the battery? (also fan does not spin) I have not tested with battery due to it being fully charged at the moment but i'll see if it can charge the battery some point...
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Project 3: DOPPELGANGER d2 Visceral
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Re: BMS Battery Alloy Shell Charger Problems

Post by pradeepswain » Apr 09, 2012 7:28 pm

48v_alloy_charger.jpg
(198.54 KiB) Downloaded 17 times
I do have the same problem with bmsbattery charger. My 48v 240watt charger died after 6 months. From outside everything looks fine.
I have checked few parts randomly, but not sure where to start looking for.

Checked the bridge rectifier on right hand side and it is good.

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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 09, 2012 11:26 pm

that is really good if you found the voltage in the rear end. some chargers require that you plug in the pack before it will turn on the output. the headway charger does that i think, using a pchannel FET which is turned on by the battery connecting to the output. some of them have relays too. if you can put the ammeter section (10A) of your voltmeter in line with the output so you can measure how much current that will help you see what is going on. use alligator clips to hold the probes on the charger leads. just on the plus side though.

guess i shoulda asked what the output voltage should be. it may be too low to charge the battery if the battery is higher voltage and the voltage you see may just be leaking through somehow and not able to be charging up the output. that would imply the diodes to the output not working to my mind.

@pradeep> can you find the 300V or so on the capacitors on the input? may have to find the traces where they run to the caps and probe them from the top. that would be output of the rectifier. looks like your ICL is still intact though. that usually is what blows on the vpower chargers.

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Re: BMS Battery Alloy Shell Charger Problems

Post by miuan » Apr 10, 2012 2:00 am

miuan wrote:The 900W made quite a lot of smoke last time I used it but it still worked. Haven't used it ever since, I need to have a look what's broken inside.
So I found one loose 5W resistor near the big transformer. Soldered it in place and turned it on again. It works, but 2 things have changed.

First, the fan turns on immediately upon battery connection, not only when cooling is needed, as it did before. Not a problem really.

Second, there is a third led behind the front panel that starts to shine weakly after a while, accompanied by a zzzzz sound and a corresponding decrease in current, suggesting the device is PWMing for no apparent reason (battery only 50% charged, circuit far from full voltage). The decrease is gradual from base 9A current down to say 5-6A in 10-20 minutes, but still it's kinda random and drifts about 1A in a matter of seconds, while the zzzzz sound changes audibly from more PWM (when lower current is displayed) to less.

Good thing is the smoke is no more there after I soldered the resistor back. But it still seems like there is some bad contact in series that causes voltage loss and fools the V sense circuit to see full voltage, inducing PWM.

I tried, but could not find any other loose parts.

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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 10, 2012 8:41 am

the pwm frequency is so high you would never hear it i think. do you have a picture of which big resistor that was and what the value is? the fan would be turning on when the op amp that controls the output is telling the front end to send juice to the back. so maybe the current is not getting through to the back end like it should. these with the TL494 are different from the newer designs, but the 5W resistor may be a clue.

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Re: BMS Battery Alloy Shell Charger Problems

Post by miuan » Apr 10, 2012 9:30 am

dnmun wrote:the pwm frequency is so high you would never hear it i think. do you have a picture of which big resistor that was and what the value is? the fan would be turning on when the op amp that controls the output is telling the front end to send juice to the back. so maybe the current is not getting through to the back end like it should. these with the TL494 are different from the newer designs, but the 5W resistor may be a clue.
I recall I could hear the charger buzzing even before I had this problem, as soon as it started to taper down the current. But the 3rd led never lit before. So this is something to think about. For the record, I have the newer style charger with big heatsink, red LED display and Amp/Volt switch.

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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 10, 2012 9:43 am

i noticed there are two different chargers in the pictures. i have never seen either one.

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Re: BMS Battery Alloy Shell Charger Problems

Post by pradeepswain » Apr 10, 2012 8:35 pm

The capacitors right next to rectifier rated 200v are showing 166v on multimeter. Is that the starting point in the circuit?

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Re: BMS Battery Alloy Shell Charger Problems

Post by recumbent » Apr 10, 2012 9:31 pm

I have the EMC 600 model just as "rui_fujino" posted with the first three pictures. In fact they are identical inside except for the wire colors (inside) on the front end.

Just recieved it yesterday and it seems to work fine, the fan comes on as soon as the battery is connected. The 2 screws on each side of the charger where the heat sinks for the mosfets are STRIPPED, and have been painted black afterwards like it's been repaired.

My confidence level towards this charger is diminishing by the minute. Hope you guys figure what's wrong with your chargers. They might surprise us and actually work for a couple years.
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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 11, 2012 2:16 am

pradeepswain wrote:The capacitors right next to rectifier rated 200v are showing 166v on multimeter. Is that the starting point in the circuit?
yes, the 166V is the rectified RMS voltage output from the bridge. it is DC voltage, charge stored on the capacitors that is then pushed through the transformer at high frequency, to induce current to flow in the secondary windings of the transformer, and that secondary winding is what is connected to the back end through those 5-6 legs soldered on the output of the transformer.

several things can go wrong here. the switching transistor that pushes the current into the transformer can be bad, or the feedback circuit to the front end from the back end can be defective and not force the transistors in the front to switch.

in the back end the ground is negative and should be easy to find running from the transformer to the output wire. the big toroid in the middle of the current flowing to the back end helps reduce the voltage spikes in the back end as the current pulses come out of the transformer, then go through those diodes in the top of the picture and out through that big wire loop, which is called the shunt, to the positive output of the charger. the little black IC next to it, i think it has LM355 on it, is where the op amps live that tell the charger whether it should be running or not depending on the output voltage. those little blue trimpots next to the op amp help make the final adjustment of the voltage that turns on the front end, and the fan, and the other op amp in that package knows when there is too much current flowing through the shunt when the delta voltage drop across the shunt climbs above the set point, which is set by the other trim pot. so follow the traces for those and maybe you get some idea of which traces go to which function. those op amps drive the leds too, but not the same op amp usually.

so you should be able to find the output voltage across the diodes, all the way back to across the output cap. if you don't have voltage on the two traces coming off the diodes, they could be toasted.

the TL494 is the controller IC for the feedback from the back end to the front end. i am no so familiar with this older type, learned more about the newer integrated chargers myself. but one of the aussie guys knows them fairly well and may have some ideas too. this is essentially a self teaching thread, blind leading the blind sorta thing, so any help is appreciated.

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Re: BMS Battery Alloy Shell Charger Problems

Post by pradeepswain » Apr 17, 2012 7:24 pm

Thanks for the detailed information. Took a while to check the remaining circuit from following your comment.

I guess I've found the faulty part. The transformer YC-4803J does not show anything significant in output side. The input 4 legs show DC287v each. But voltage on the 6 legs on secondary side is 0.2v. I presume it should also have a fluctuating DC voltage. Or could it be the switching transistor that's feeding current.

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Re: BMS Battery Alloy Shell Charger Problems

Post by rui_fujino » Apr 19, 2012 6:24 pm

Here is another dead charger. this is BMS Battery Alloy shell 400w
Attachments
2012042006580001.jpg
over all view
2012042006580001.jpg (131.46 KiB) Viewed 303 times
2012042006580000.jpg
cap blown clean and resistor blown too
2012042006580000.jpg (127.32 KiB) Viewed 303 times
Project 1: Apollo slant hard tail MTB 52v lifepo4, conhismotor, 52T-11T gearing 39.6mph top speed (with pedal)
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Top speed 45mph(72.4km/h)
Project 3: DOPPELGANGER d2 Visceral
Project 5 Specialized Epic20s2p (83.5v 10ah Lipo), 30kg,HS3540 sensored (MethTek), 12FET lyen @ 50A
Top speed 45mph(72.4km/h)
EV miles: 3000miles (2015/06/26)

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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 19, 2012 10:11 pm

pradeepswain wrote:Thanks for the detailed information. Took a while to check the remaining circuit from following your comment.

I guess I've found the faulty part. The transformer YC-4803J does not show anything significant in output side. The input 4 legs show DC287v each. But voltage on the 6 legs on secondary side is 0.2v. I presume it should also have a fluctuating DC voltage. Or could it be the switching transistor that's feeding current.
the 287V on the capacitors is the DC voltage sitting on the output of the rectifier diodes. i once had the data sheet for that TL494 and tried to understand how it works to cause the switching in the front end. and if those were some kinda "push pull" transistor pair that were a balanced pnp and npn transistors that would switch on and off with the sawtooth pwm output of the TL494. all just guesses on my part, but somehow the signal from the 494 has to get up to the base on those transistors, or gate if they are mosfets. that's kinda stream of consciousness, about the best i have right now.
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this is for the TL494
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Re: BMS Battery Alloy Shell Charger Problems

Post by dnmun » Apr 19, 2012 10:21 pm

rui, can you tell what size that resistor is that burned up? maybe someone else has the same charger open and can read the label for you for the capacitor. it may be symmetric with another identical one there, also same with the resistor. i noticed they have identical circuits for each of those transistors, if these are in that loop.

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