Dead BMSbattery charger

[Farfle]

Got a 400 watt BMSbattery charger a few weeks ago, have put about 40 cycles on it and it gave up the ghost today, plugged in AC, plugged in battery, fan turned on and the factory smoke came out, followed by the fan turning off. Ill post some pics once i pop it open, sounds like a component rattling around on the inside. looks like a compact 400w charging solution is still unavailable .

[neptronix]

Is this a kingpower charger we are talking about?

[dnmun]

why can't you fix it?

[Hillhater]

I guess there is a reason they are so cheap !
.. But it would be good to know what failed.

[dnmun]

usually it is the ICL. or the output caps when they reverse polarity.

[FMB42]

You should always plug the charger into the battery first and then plug the charger into the AC outlet.

Reverse the above steps when disconnecting the charger (i.e. unplug the charger from the AC outlet and then from the battery.

[bobale]

Well, it's a bit late for that advice, isn't it?

On a serious note Farfle, what failed in that charger? I'm interested in buying one, so I would like which are it's weak points.

[Farfle]

huh. always got a massive precharge spark when i plugged it into the batt first, so I have been running ac, battery, then hit the on switch.

[dnmun]

yes the spark is from the battery shooting current back into the output caps of the charger. just like when you plug in the controller. the bigger the caps and the higher the voltage the bigger the spark. energize the charger first.

if it is rattlin, take a picture of what blew up and we can figure out what it is. i have fixed a buncha chargers now and i think almost a dozen other chargers i have helped fix by sending them the ICLs i bot at mouser.

[amberwolf]

Ill post some pics once i pop it open, sounds like a component rattling around on the inside.

So....where are those pics?

My bet is on a cap blown up, but could be a fet or diode.

[Spacey]

I had the same go wrong on a 43.8V 8A Kingpan charger the other week. The cap had vomitted itself after about 50 charges.

I replaced the cap and turned on the charger and it instantly blew the cap again.... any ideas?

What is this ICL part, am keen to figure out how to fix these.

[mxer]

Sorry to here about this I have just ordered one of these, it's been tested and is ready to ship, Hope mine don't go pop , I guessing BMS don't give a 12 month warranty

Just a matter of interest what did you have BMS set it too ? mines shipping out at 50v 6 amps....

[dnmun]

yep, too bad we never saw what was broken inside. it may have helped others too.

in order to prevent the spark arcing across the plug, always turn on the charger first, then plug in the battery. this should be obvious from the big spark if you don't.

[rojitor]

Do not expect repair neither refund from bms battery, they do not take responsibility for their mistakes, i had a similar problem and i lost my cash.

[auraslip]

these aren't bad chargers. they just have the issue of being made with the cheapest parts available. some of them will fail. just like the damn hall sensors in my motor did just now.

[dnmun]

until someone actually shows us the inside and we can figure out what failed, it is kinda impossible to make blanket statements about what failed or why. to imply that the failure is because of BMS battery built them poorly fails to acknowledge that these chargers are made by others and just sold by BMS battery. they don't know any more than you about them.

most of these chargers can be fixed easily, at very little expense. but we are a consumer culture, throw it away and buy a new one.

i have found that repairing this electronic stuff has forced me to learn electronics for the first time. in a really practical and useful manner. no wasted time studying laplace transforms and circuit equations. which i once did in a previous life.

just figuring out what the parts inside do has led me to be able to see them in the big picture format finally. kinda like richard and jeremy and wayne can see this stuff, but of course not at their level, but rewarding for me.

[Farfle]

I still have this charger actually, let me go grab it and upload some pics, IIRC the main transistor died.

[dnmun]

the power mosfet in the front end may have a chinese fake part number on it, but the schottky on the rear end should be easy to find. the rattling was what was curious.

[Spacey]

Just for the record I have bought about 20 of these controllers, have had only 2 die, one of those was probably my fault the other just a dud.

Better than most Chinese quality control I would say. Will upload some pics myself when I get back to work on Tuesday where the controller is.

[Farfle]

ok, heres the picture: it looks like the large yellow wire wound circle of something, (ferrite torroid?) has come unhooked from one end due to vibration. Any idea on what damage this could have caused?

[dnmun]

i think people like richard or jeremy would know best what the toroid does, but i assume if smooths out the ripples in the voltage of the front end which the power mosfet has to switch on and off to send through the transformer at high frequency.but i don't really know.

but i think if you start looking at the traces where it connects to the pcb, you will find that the traces have torn off the pads where the mounting pins go through the pcb and you may be able to solder over the crack in the traces after you stick the toroid back down with some hot melt glue. should be able to use a thin coat and stick it back in place. then solder or you can use a small wire as a bridge from one part of the trace to the other if a large piece is torn out.

one of my headway chargers someone donated to me for my electronics education had a trace torn off and when i found the break and soldered it back, the charger worked fine.

that charger was broken at manufacturing i think. it looked to me like it had been broken when they either jammed the pcb into the case or dropped it and the heat sink pulled the mosfet off the trace and tore it open. that was the source leg of the power mosfet so everything in the back end i checked all worked and i had to isolate it to the mosfet before i found the crack in the trace. it took a magnifier to see the crack, but that was it.

[amberwolf]

Dnmun is probably right. It kinda looks like the whole thing was possibly dropped before installing into the enclosure; even the central transformer has a cracked bit on it. Such an impact could easily have caused a large heavy part like the toroid (that is only mounted usually by the two or four wires on it to the PCB) to flex quite a lot, pulling the wires out or at least breaking the solder joints and/or damaging traces.


I can't clearly see enough of the board to figure out much of it or see even the toroid leads/etc., though--it's too dark. Can you take some pics either out in direct sunlight, or with a spotlight of some kind shining on the PCB at the same angle the camera shoots from? And if your camera has the option, set it to Macro and also to capture ambient light plus flash (my camera calls this Slow Synchro, in the flash options).

[rui_fujino]

Well, since so many of us here are interested in what's inside and How it "broke" here is couple more pictures from my 600w BMS charger (83v 5A)
[attachment=2]IMG-20120207-00513.jpg[/attachment]
[attachment=0]IMG-20120207-00514.jpg[/attachment]
[attachment=1]IMG-20120208-00511.jpg[/attachment]

PS, This is my 2nd 600w Charger that broke....

[rui_fujino]

I'm currently Looking into what/where is the problem...taking a long time checking all the connections...
mean while I went back to my first charger that came broken, turns out, one of bridge rectifier got yanked off the pcb so I guess all i have to do is to replace them

left leg is completely unattached

[ZOMGVTEK]

ok, heres the picture: it looks like the large yellow wire wound circle of something, (ferrite torroid?) has come unhooked from one end due to vibration. Any idea on what damage this could have caused?

That's right next to the DC side, right?

It will probably work fine if you solder that coil back up.