BMS Battery Alloy Shell Charger Problems

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

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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)?
 
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.
 
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!
 
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

heathyoung said:
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 :)
Click to expand...
 
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.
 
alsmith said:
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.
Click to expand...

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. :idea: Shipping is toooo expensive to have these kinds of failures. :roll:
 
I actually have one of these on my workbench at the moment, (a 400W) courtesy of Hyena - he tried adjusting the voltage, and blew out the power transistors (oops).

To be honest, they are a fairly ordinary design - completely bare bones, absolutely no mains filtering components (so completely unapproved for use on any mains supply). They are as basic as you can get - inrush current limiter, followed by a bridge rectifier, 2 caps and switch (urk!) wired with thin low voltage non-mains cable - oh dear. Don't be tempted to put a bigger fuse in, you may find that these wires become the fuse!

Standard push-pull topology like PC power supplies everywhere, with a TL494, and transformer isolated drive.

The loop compensation is crap, so they will have a tendency to fry themselves if something gets a bit out of whack, and like most of these with no current detection in the high side (even most PC power supplies have a CT in the highside) and transistor ratings on the very edge ~ guess what dies first.
 
heathyoung said:
I actually have one of these on my workbench at the moment, (a 400W) courtesy of Hyena - he tried adjusting the voltage, and blew out the power transistors (oops).

To be honest, they are a fairly ordinary design - completely bare bones, absolutely no mains filtering components (so completely unapproved for use on any mains supply). They are as basic as you can get - inrush current limiter, followed by a bridge rectifier, 2 caps and switch (urk!) wired with thin low voltage non-mains cable - oh dear. Don't be tempted to put a bigger fuse in, you may find that these wires become the fuse!

Standard push-pull topology like PC power supplies everywhere, with a TL494, and transformer isolated drive.

The loop compensation is crap, so they will have a tendency to fry themselves if something gets a bit out of whack, and like most of these with no current detection in the high side (even most PC power supplies have a CT in the highside) and transistor ratings on the very edge ~ guess what dies first.
Click to expand...

Based on this not so positive analysis, is there anything that can be added to this specific 400w model to make it last longer? Fans? Lower amps to 4-5A instead of 6A @48v?

What about adding/hacking in something inside the unit that might be worth doing?

Are the same watt rated Meanwell PS any better?

Thanks. :D
 
Plus with little or no QC, it's easily possible to isntall electrolytic caps backwards, which can result in exactly what you saw--runs for a very short time, then BANG! :(
 
it is a stretch to think they would put it in backwards, but we have all seen stuff that was hard to believe when we open these things. when the cap blew it left the can in place so you can verify it had or did not have the correct polarity.

that cap may be the filter next to the voltage reference from my view of where it is located. that might be the reason it was charging when it wanted to turn off, ie: from having both lights on.

but there may be something else and this cap just blew up because high voltages got to the wrong place.
 
I guess the way BMS does burn-in is 'you' get to burn-out the bad units. :lol: Then, as dnmum has pointed out elsewhere, hopefully they ship you a new one for free. Guess it's better to order and own at least two chargers. ;)

Has anyone been refused a free replacement w/free shipping??? :?:

Did anyone get a written warranty with the charger?
 
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