BMS Battery Alloy Shell Charger Problems

[amberwolf]

To me, that looks like the cap was shorted internally, pulling so much current thru the inductor that the inductor overheated and burned like that. Hard to say for sure, though.

[heathyoung]

My guess - the inductor was saturated, (even though it is designed to run in continuous mode in a forward converter) and wasn't filtering the current pulses to the capacitor (that is its purpose) - the cap wasn't specc'ed to take that sort of ripple current, and committed suicide.

This is a good reason why you don't play with the settings too much on these without scoping them properly - you change the properties of the circuit, and your component values are wrong for the application. Turn the voltage up, bad things happen.

The maths behind these is a lot more complicated than most of us would like, trust me

I could post some up, but it may make your head do something similar to that cap

[GCinDC]

replaced the 470uf 100v cap that blew, btw, but nothing...

there's a small 5v cap next door. wondered if i should have replaced it too..

[dnmun]

is there voltage coming out of the schottky diodes to the cap? past the cap?
<edit, finally read your comment, it is not the cap but the coil i though had the open trace underneath>
i was looking at your picture and i thought maybe the trace under the coil had broken, where it was burned, under the coil. i wonder if it would help for you to just use little wires bridging the traces in that region baby wire is fine. but that's a lotta charcoal. gotta be fragile.

i expect the small 5V cap is for stability in some feedback signal to the op amp over there. the voltage does go through that wire wrapped around the toroid, right? from the schottky diode to the positive output ? and i 'll look at the other pictures

[rui_fujino]

hi guys, does anyone know what was the rating for capacitor which blew up??
The charger is BMSBattery 400w charger. C11 is the one which blew

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thanks

[saiyan]

ok guys,
so i just received my bms 900w charger for my 20s lipo pack today. after more than a month of waiting since i purchased it online.
plugged it in the wall. made light buzzing noise with both led light on. so i plugged it into my 20s pack and 3-4 secs later, it made a very loud POP. lil smoke came out. right out of the box it was a dud..........

emailed bms guys, now waiting there reply.

very disappointed. waited that long for it and it doesnt even work. not to mention, my shipping cost to australia was more than the charger......

[999zip999]

How did you pay for it ?

[saiyan]

credit card. cant memebr if its paypal....... :/

[dnmun]

both the red and the green lights were on indicating charging but also indicating finished charging?

buzzing like a fly in jar or like a vibrator?

take pictures before sending it back. maybe pictures will get you outa sending it back.

[saiyan]

Ye it was abit wierd how both lights were on......
Buzzing like a fly. It still makes the noise when i switch it on, just no lights are on and its producing 0.2volts on the anderson plugs.

I dont really want to send it bak. Guna cost me more than half of whats its worth.
Will c what bms says 1st.

Its just very frustrating, after paying that much for it. Over a month wait. And its not even working. :/

[dnmun]

it may be obvious when you get it open and they will accept the picture as proof of failure so you don't have to ship it back. you can use this thread too as some kinda assistance maybe.

[alsmith]

sounds fairly similar to what happened to mine.
They didn't want the broken one sent back so wait to see if they ask for it.
Open it and look for damage / problems. Perhaps a capacitor becuase of the way it went? (Mine had a bare wire where a soldering iron had rested on it and a bad board track- the components didn't show signs of damage).
Send the pics to them if you find any problems and when you get the delaying / put off email resend to Jack Xie <bmsbattery@gmail.com>
explaining you tried their support but are having 'xxx' problems with them. (Don't forget to thank him if it gets resolved).

One more thing- they asked if I was going to be placing another order (they would put it in the same package). It's saving them carriage costs. I said no an they did send after about a week and a chaser email.

[GCinDC]

holy crap. i ordered my 900W one on June 11 and got tracking # on friday so it should be soon. this is mightily disheartening!

i'm going to video the removal from box and first turn on!

[dnmun]

@saiyan> they have a special deal on their headway packs right now. if you need a new battery and if that works, maybe you can negotiate a little better shipping fee on the new battery if it comes in the same shipping box since they already have to pay the shipping fee for the replacement charger. or buy another charger on top of the new battery, the chinese economy is slowing down and they may be hurtin. even better, we may even be able to figure your problem and fix it yet.

[alsmith]

I got 2 chargers at the same time so I would have a spare if anything ever happened to one of them. I never thought it would be needed that fast but I was pleased I got 2 of them.

[saiyan]

i will wait another day for them to reply.....if not i will email jackie.

as for buying another 1? i dont think i will be doing that. i already have batteries. ordered 16 x 5s, 5000mah lipos. 2 of them dont work aswell. lol.

my main focus is the charger, maybe i should open it up and have a look......

[rui_fujino]

If you complain to Jack Xie then I'm almost 100% sure he'll send you new one asap!
I've talked to his 3 times and all of those times he has done well!

[saiyan]

ok guys.....so i opened it dam thing up. and i think i found the component that exploded. im not tech minded when it comes to circuit boards and small components so can you guys please tell me what it is?

in the 1st picks, it looks to be a freaking wet cigarrete butt or somefin. pretty sure its part of the component that blew off.......

in the 2nd pick, if you can see the numbers, it says (C201). im confident thats where it exploded at.

can any1 tell me what component this is, what it does, maybe why it exploded and where i can get it?

thanks for all the help guys........

[rui_fujino]

that looks like capacitor to me. What you have blown there is a capacitor and both parts are from it.
I'm not sure what size capacitor was blown...can you take a larger over alll picture of the board (PCB)?

[saiyan]

just emailed jackie.

and the larger photo.....

[dnmun]

yep, an exploded electrolytic capacitor it appears. can you read what the labels say on the can? maybe someone else has one open and can read it if yours is blown up too bad.

[alsmith]

My chargers are different so can't help unfortunately.
Not too often you see the capacitors that badly self destructed. It looks like it's a poorly constructed one so if you can find the value and replace it with a decent one you could well end up with a (spare) working charger.
Have you sent the pic to Jack Xie- it's hard to argue with that!

[deVries]

Hi, question based on your post... is it safe to turn down the voltage and/or amps on these units from "the factory" presets?

Are these so crappy quality that it's not worth getting these? Get a Meanwell & do the Fechter mods instead?

Thanks.

Subject: BMS Battery Alloy Shell Charger Problems

My guess - the inductor was saturated, (even though it is designed to run in continuous mode in a forward converter) and wasn't filtering the current pulses to the capacitor (that is its purpose) - the cap wasn't specc'ed to take that sort of ripple current, and committed suicide.

This is a good reason why you don't play with the settings too much on these without scoping them properly - you change the properties of the circuit, and your component values are wrong for the application. Turn the voltage up, bad things happen.

The maths behind these is a lot more complicated than most of us would like, trust me

I could post some up, but it may make your head do something similar to that cap

[alsmith]

I would say crappy Quality Control and poor component selection (ie the cheapest) rather than crappy chargers. A lot of these problems seem to be at first switch on- that means they can't be tested by the manufacturer or they would see the problems. The same with the components they buy/use.
If/once the chargers are working they seem to be ok.

[deVries]

I would say crappy Quality Control and poor component selection (ie the cheapest) rather than crappy chargers. A lot of these problems seem to be at first switch on- that means they can't be tested by the manufacturer or they would see the problems. The same with the components they buy/use.
If/once the chargers are working they seem to be ok.

This is what I find so crappy about this situation. No reason why BMS can't burn-in & test these a few cycles. They are already adjusting the volts/amps settings, so there really should be some burn-in time too. Also, shake to listen for loose parts. I'd pay $5-$10 more for a decent burn-in. The expensive chargers over $100 should be getting that burn-in for free. Shipping is toooo expensive to have these kinds of failures.