Chinese seller of dangerous BMS

Hi ,

First of all, the sellers I bought from were all extremely correct and on time but …

This is my story , I bought a SmartBMS from this seller:

I connected all the cables to the battery following the instructions (one 10s 17000mAh) with double check the balancing connector voltages, and when I connected the balancing connector to the BMS there was a short and the bms caught fire.

In the final the balancing port connector supplied by the seller had two short circuits :

This is my cells :

and the seller says that it is the fault of my connections by adding philosophical personal motivations regarding my competence in the field …

What to say, fortunately there are also responsible sellers … a battery pack can be very dangerous and provide a card with short circuits is a serious problem.

All ended up just a few burns to the fingers …

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Got a pic with the wiring before the burn? Reason I’m asking cause that’s a 15/16 pin connector, so it would need to bridge a few pins for 10S spread across it

I can’t tell if the bridges are across multiple used pins or 1 used and the rest empty

It´s just wired wrong, nothing wrong with the BMS itself. The question is, if they are too stupid to get a proper wiring diagram to you, or if you just had it wrong. Do you have a diagram from them?


double check the wiring with a voltmeter so you always get it right.

I do not have a pic of the connector before the burn . The seller sent me the connector configured for 10S in the wrong way , because this BMS can handle from 10 to 15S battery packs. You can see the mistake following this table:

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Thanks for the advice anyway, I double checked the voltages before to insert the balance connector in the bms …

The wiring to the battery pack was ok, but the connector provide by the seller had two wires in the position where the board had a short circuits …

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Yah, wiring diagram and soldering on bms is ok… I think they buy these wrong connectors from an other factory and got a wrong batch or something… really unfortunate for your pack…

Just double check your cells, they might be damaged a bit, but you can often rescue them, if they´re not burnt overall!

Yes, the cells voltage at the moment is at 3.6 also the burned cells ( LG MJ1 ) and are park in a safe place for a while. At the first recharge, I will understand the extent of the damage, but considering the voltage to 3.6 I am optimistic.

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Yeah the cells don’t look too badly damaged. They might have just gotten the black mark from the burning balance lead. Charge them and then discharge them with a balance charger if you can

normally they suffer a few lifecycles, but the balance wires work as fuses and often prevent further damage.

Thanks for all the advices !:+1:

I’m very sorry that this happened and I am glad no one was injured.

However, while the vendor may have been Chinese, it is irresponsible to label all Chinese electronics as defective. The computers we are communicating on are built with electronics manufactured in China.

Of course, at the beginning of the thread I wrote:

" First of all, the sellers I bought from were all extremely correct and on time but … "


Side question: Why did you decide to go with MJ1’s?

Beacause I founda 50 pack cell of second hand but now I am using lipo .

Thank you for sharing your unfortunate experience. This type of information is helpful.