BMS Battery Alloy Shell Charger Problems

I just wanted to thank everyone for the information and discussion in this thread.

I have two of these BMS chargers. One seems to work, the other doesn't seem to indicate charging even though it is putting out the correct voltage unloaded, the LEDs don't change when the battery is connected.

In any case, I was considering getting some more of these, but based on:

1) no reasonable cost postage options,

2) low quality of the components and the designs,

3) high failure rate,

4) inadequate warranty and customer support,

I think I will go another direction. Too bad, the packaging of these is pretty nice, and the size, but the reliability is not there.

If the postage was something like $10-20 I might accept some of these issues, but they still need to be reliable even if not warranted.
 
alan, why does your charger have voltage on the output when these don't?

they seem to give good warranty support. i think everyone has gotten a replacement who had problems.

i think greg's charger is the only one we could not get replaced, but even his charger might have been replaced if we could show a good reason for them to replace it. he had used it for awhile, but it would be worth a try, imo.

there was no reason for him to come here and hijack the thread to prove his oneupmanship. we didn't go puke on his threads.

i don't think the failure rate is as high as it seems either since these are just the people with problems but a lot of the chargers have been sold to sphere dwellers since the doc posted up about them 2 years ago now. these are big chargers. it still seems they are the best deal available. jmho
 
I bought my pair of them maybe a year ago. I'm not finding the order now. I didn't test the 240 watt unit right away, I did use the 400 watt unit a number of times and it has been okay. These units are not UL listed which creates problems for me since we have rules at work about equipment being UL listed. For example non UL listed equipment cannot be sold in stores as I understand it, or at least it cannot be put on display where customers might come into contact with it. Heathkit ran afoul of that years ago.

Another thing is the power rating seems to be incorrect. The 240 watt puts out 2 amps at 75 volts which is 150 watts, and the 400 watt puts out 75V 4 amps which is only 300 watts.

I have heard some of these units have voltage at the output with no battery connected and some do not. I'm not sure if the design changed or if it varies with the models. I wonder if all the chargers sold under this designation are really the same design. There may be some variance.

It seems from this and other threads I have read that if you receive a bad one they will replace it right away, but it is not clear they will replace it if it fails later on. Will they replace it six months or a year later? I have read (in a number of threads) about a lot of bad ones out of the box, and many that failed later on.

What is the failure rate? It seems to be high, but it is hard to know accurately.

What are the consequences of the failures? Do the chargers just quit, or is there a risk of battery fire? So far I've only heard of chargers blowing up, no actual fires of either the charger or the battery. Though Greg's unit clearly got very hot. No major fires, thankfully.

The BMSBattery charger prices are excellent but the high shipping prices are affecting the cost effectiveness of the product. For about the same delivered price as the 400 (which is really only 300) watt unit I bought a 300 watt voltage and current adjustable regulated supply with various listings, potted components, and 5 year warranty. It is not quite a completed charger, but it has more and probably better quality components, just for comparison.

edit: removed UL listing from the power supply I found since just went to verify and don't see that one. It has a bunch of certifications, but perhaps not UL.

Hopefully BMSBattery will address the quality control problem and figure out more cost effective shipping options. UL listing would be nice, but for most may not be an issue. Aside from many workplaces and retail outlets, are there any requirements for UL listing that would affect users of these chargers?
 
deVries said:
You obviously have not read my posts clearly throughout this entire thread. I don't have a problem personally despite you saying I have one with these chargers.

Ok my apologies, I'd missed reading part of the thread.

The chargers do seem fine imo but like all purchases you need to understand what you are buying before committing your money.
 
deVries said:
captain387 said:
I have an older 900w version, and the battery has to be connected in order to initiate power output.

Dr. Bass installed a switch to turn the power on without connecting a battery in this thread. (Plus other helpful mods)
http://endless-sphere.com/forums/viewtopic.php?f=14&t=29096

The colour of the +/- leads where indicated on the lid of my charger(Brown positive, Blue negative).

Did these mods Doctorbass did match-up with your 900w charger components to do the same mods?

Thanks. :)

I haven't undertaken any of these mods as his charger is the 2000w model and has easier access to the bottom of the control board.
My charger's board is sandwiched within the aluminum shell and the fets are attached to the side wall with heat transfer paste.
I wanted to use the charger before I took it apart and broke something.
My main interest was to double check the polarity of the charger before I put on new connectors, but decided to wing it.
ON MY CHARGER (no guarantee that this will no break your charger) reverse polarity on 12s lipo did not let out the magic smoke, it did not trip the relay, and in actuality it did nothing at all.
Switched the wires and it started charging.
I'm at 55 charges
120v input to charger
49.2v output at 7.5 amps
I removed the lid with the handle and installed a piece of sheet metal with a fan attached to replace the lid.
Plug in fan, turn on charger, connect battery pack, reverse order when battery is charged.

Good luck.
 
captain387 said:
49.2v output at 7.5 amps

Subject: BMS Sold... EMC-1000 900w Units...

Is this the amp-setting you requested, or is this an actual amp measurement you took? That's quite a conservative setting for your 900w unit.

Does anyone know where to adjust the amp settings up/down on these 900w units? I've decided to drop down the amp setting from 15A @ 48v to 11A, which is about 25%+ further "de-rating" of the spec max.

Thanks. :)

Btw, @ 48v w/max spec amps of 15A this is only 720w, so it seems this 900w charger is "de-rated" already??? Call it about 810w "burn rate" total by adding-in heat loss inefficiency of 87-88%. That's at least 11% under the charger's 900w rating IF it can be believed. :lol: :roll:

49v @ 11A is about 540w which is "de-rated" 40% from its 900w rating, so that should be super low stress on the charger, hopefully!!!
 
Hello! all forum members, i am a new member from Sweden and i have just bought two of those Alloy shell 600w charger.

I have one at work and one at home, charging 49V 8A just under 400W.

They get barely worm at all. Later on i will slighly raise the voltage to maybe 50V.

So far so good.
/Lasse
 
Well, the charger was second hand and the previous owner had it set at 72v, 11 amps, I think.
Everything with my bike I have set it to be extremely conservative from charging at below 1 c and running my speed control at 60% its rating.
I do plan on enlarging my battery pack in the future and wanted to get a charger that could meet those needs.

Here is the inside of my charger and the adjustment pots I used.

Bms charger v and c.jpg
 
yep, great picture, you can see the daughter board that carries the TL494 chip that controls the feedback to the front end.

if you follow the traces through the trimpot, the wiper will go up to one of the pins on the 494, for both the V and current. go google up the TI pdf technical sheet for the TL494 and save that file for use. you can follow the pinout in the pdf to see where the V&I feedback pins are.

about the power, i understand the power numbers are based on what the transformer can handle at max. derating may also benefit the other components, but i think it is the transformer size that determines power handling.

ok, i went and looked for it. right here in my documents. the inputs are at pin 1 and pin 16.

the voltage trim pot will be in the resistor divider bridege between the ouput and the ground and the current trim pot will be in the cicuit that includes the shunt resistor in the negative traces with the output negative as ground, and the voltage on the shunt high end the input to the 494.

editors note: ask questions about the IC diagram in the pdf if you want, the initial schematic kinda encapsulates what the pwm chip does, how it controls those output transistor that then turn on and off the push pull transistors heath was talking about, in the front end.

that's how it knows to switch more current through the transformer, and the input switching transistors stay on longer because of the pwm making them do it.

edit some more, i just looked at this Vpower charger with the daughter board carrying the 494. the current sense connection from the high side of the output shunt resistor is at pin #3 from the right on the bottom of the daughter board, and since this is a 36V charger instead of a 48V charger it has a small 1/4 watt through hole resistor on the pcb next to the daughterboard to set the voltage, and that connects to the voltage from the high side of the schottky diode in the positive side of the output comes on to the daughter board at pin#4 from the right on the bottom, so see if that is the same as on your daughter board
 

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that was really useful to analyze the circuit for the TL494 based charger. i have a Vpower charger open and it is almost identical to the schematic. different resistor values but some of the ceramic caps are the same. my charger has two schottky diodes to the output, one before and one after the choke, the inductor in the back end.

i can see where the two transistors on the daughterboard causes the current in the small feedback transformer to switch on and off according to how much the TL494 is commanding it to. this feedback transformer then drives the base voltages of the two NPN transistors in the front end. and they have diodes so that one transistor is on while the other is off and the two together keep the main transformer cycling more or less current depending on the height of the voltage induced on the base by the feedback transformer so that determines how much current goes into the main transformer to induce the current to flow in the back end part of the main transformer. this current then flows out into the back end through the schottky diodes and the current flow through the shunt in the negative trace of the back end gives the feedback for current onto the daughterboard.
 
interestingly, I thought the page looked familiar, and when I went to save it locally, it said it already existed, from last year. :? So I searched ES to see where I probably found it from, and found this thread by the website owner:
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=26859&p=388000
;)
 
Here's my story.

1200W charger, 49.8V out the factory for a 4.15V per cell end voltage with 12s of Lipo.

Worked great for 6 months charging 12s2p pack up every day. Left it unused for a week, turned it on to charge again and POP tripped out the ring main in my house

Now it won't turn on at all. Fuse in plug and in unit remains intact. Took the lid off, everything looks intact inside, no burnt out components of visibly broken connections.

Just before it died it "clicked" on and off 3 times I could hear the relay engaging and disengaging before it tripped the power. Any ideas?
 

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was the battery already plugged into the charger when you plugged the charger into the wall outlet?

did it actually charge during the periods it was clicking the relay. was the red light on and off as it clicked? are there any burned traces or shorts on the other side of the pcb? if the fuse did not blow there should be voltage to the diode rectifier bridge and then through that onto the input caps.
 
the battery was not plugged in, my process remained the same as ever. turn mains socket on at the plug, turn toggle switch on back of charger, wait until LCD display shows correct voltage (guess thats caps charging up) That's when i usually plug in the battery, but before i reached that stage the relay clicked on and off a few times and the screen flickered on and off before finally dying completely ( and taking the whole ring main with it)

I havent unscrewed the PCB to see if any traces are burnt on the underside but as I say the top of the PCB and all components look factory fresh, what else should I look out for ?
 
You paid about $250+ including shipping. I suggest if you can't get a quick fix here or with Jack at BMS, then ask for a warranty replacement. ;)

P.S. Their shipping prices are waayyy tooo high, IMO. These guys need to offer Sea Shipping now!
 
fuse did not blow. the clicking of the relay is normal as it charges up the output caps i assume. but the current draw blew the circuit breaker.

with that much shorted, but the fuse not blowing implies the main power cord has shorted. test continuity between each leg including ground and the also to the housing of the charger.
 
I replaced the main power cable with one I confirmed to work on a different device. Wires from socket in charger to PCB look intact

Tom
 
if your torn between 600W vs 900W, the 600W is much smaller, fyi:
20120812_110541.jpg


my 900W seems to be working fine.
 
okay this is my first youtube video so please dont criticise too much on quality ect..
looks like how people charge may be the cause of charger braking so I filmed myself charging mine.
[youtube]qa9nmpK54Yo[/youtube]
 
nonlineartom said:
I replaced the main power cable with one I confirmed to work on a different device. Wires from socket in charger to PCB look intact

Tom


did you get this resolved?

i am slow, but now thinking about this and how you mentioned that the relay clicked, but never engaged the battery to the charger.

the relay coil current is coming from the battery so i wondered if it has a bad connection between the battery and the plug.

you can do this while every thing is turned off by measuring continuity between the negative lead on the pack, and the negative output on the pcb. and then measure continuity between the positive terminal of the pack and the place where that diode is on the pcb next to the bottom of the relay. that diode is there to prevent the charger from being reversed when plugged into the battery so the end of the diode should be connected to the B+.

it did click though, see if it clicks when you apply the battery again, without the charger powered up.
 
No life from it at all. No relay clicks on battery connect, no LED or LCD life either.

emailed BMS battery, quoted them my order number and explained the symptoms, they asked for pictures which I provided, 24 hours later they emailed me back and said they would send out a replacement and pay shipping if I shipped them the faulty unit so they could give it a poke and see what went wrong. Seems a fair deal

Stupid me hasn't got round to posting it off yet but I'll report back with how long the turn around is, fingers crossed.






dnmun said:
nonlineartom said:
I replaced the main power cable with one I confirmed to work on a different device. Wires from socket in charger to PCB look intact

Tom


did you get this resolved?

i am slow, but now thinking about this and how you mentioned that the relay clicked, but never engaged the battery to the charger.

the relay coil current is coming from the battery so i wondered if it has a bad connection between the battery and the plug.

you can do this while every thing is turned off by measuring continuity between the negative lead on the pack, and the negative output on the pcb. and then measure continuity between the positive terminal of the pack and the place where that diode is on the pcb next to the bottom of the relay. that diode is there to prevent the charger from being reversed when plugged into the battery so the end of the diode should be connected to the B+.

it did click though, see if it clicks when you apply the battery again, without the charger powered up.
 
Still haven't got round to posting back my faulty 1200W unit, bought another one in the meantime, I need a second one anyway. Took 3 weeks to arrive, plugged it in... BANG big flash of light out the plug and that oh so familiar smell of cooked electrics. Tripped the ring main in my house, turned the power back on and began diagnosing the fault. The fuse in the charger had not popped, it had vaporized. :roll:

I noticed the toggle switch was in the "on" position when I had plugged it in, so turned it off, replaced the fuse with another 10A fuse, plugged it in and turned it on at the socket, BANG exploded the fuse again, the unit wasn't even switched on at this point. Odd?!

Seems like a dead short in the AC side of the circuit then, opened it up to see if there were any lose wires inside, it looked ok. Until I noticed something..

I really know very little about AC electrical stuff, but should the live and the neutral line really be connected to the same "IN" point on the PCB like that?

Can't see any visibly loose connections or charred components, really annoyed this charger was DOA especially as it was replacing another dead unit. I want to get back on my dam bike!
 

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