10S5P battery pack with BMS wont charge

The Ballance connector was not connected when soldering.

Can you show me on this picture where I need to check?

I can show you on that picture, but I purposely used the picture you provided to ensure we are measuring the correct spot

Yes but I can’t see where to measure because of the shrink wrap. And I can not just measure the wires since all the leads are positive.

Sorry they are not positive. They are between a positive and negative

you can probe the pin easily, and then put your negative lead straight to the battery negative cable.

Yeah okay. That I have done.

When I have connected the probe to the first pin from the right. And the other to the negative I get a voltage of 3.6

When I connect to the negative and then the last pin I get 36V.

So it should work. I have done a test all the way through were I got.

  1. 3.6V
  2. 7.2V
  3. 10.8V

And so on

I don’t understand how can you get a spark when connecting the negative wire to the BMS while the balance leads and everything else is disconnected. It’s not a complete circuit so unless you had other stuff connected, it should not spark.

When I hooked my BMS I did the same, I soldered the b- from the BMS to the minus of the battery. Then c- to the charging socket. Then measured all pins from the balancing connector to make sure everything is ok. Then plugged it into the BMS and proceeded to charge the pack.

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Maybe try measuring from b- on the BMS to last pin on the balancing port. You should see 36v.

I do see 36v. I thought first that the spark was a simple connection spark. But I’m not sure

Then maybe the BMS is dead. You can’t get sparks on incomplete circuits so some other wires must have been connected or something. Maybe it’s time to test a new bms…

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Okay now i tried again with no diffrence. But when i unplugged the BMS i took out the negative leads first. Nothign happened. Dont you guys think that is why it does not work? When a BMS has connected the 10 leads alone it is said to burn out on the website.

So if nothing happens now then it must have happended before therefore the bms is broken?

Here’s my take, Something was wrong when you encountered the spark. Then when you implemented the plug, and got no spark the second time, the damage was already done. You don’t get a spark now because whatever short you created while wiring the bms is fried. The spark was the first indication of a problem. Read, Replace, Repeat.

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Sound right. Now i just have to make sure that i dont make the spark again. Do you know if it is possible to make the spark with the negative wire from the battery pack and the BMS and the soldering iron`?

I would say only if something else is connected incorrectly.

Do you have a smart idea of how to test.

I can use the ground and positive to get a total of 35.6v Which is what i want.

I can measure on the Ground of the pack and then measure each of the cables in the balance cable to get.

  1. 3.6V
  2. 7.2V
  3. 10.8V

And so on. So that seems to be in order.

Not specifically…you shouldn’t be seeing sparks though while connecting a bms

What everyone here is saying, is that you should not have power at that bms for any reason unless the balance plug is connected, or your wiring is incorrect in some way. The only way that BMS receives power is those balance leads. If you got a spark, then there was either power at your BMS, or power at your negative cable(eg incorrect wiring, positive lead instead of negative ect…).

For that spark to have occurred, you would have HAD to have power at the bms, or you were connecting the positive lead of your battery instead of the negative. There is no other possible way for that lead to spark. Unless your solder iron has in internal short(highly unlikely).

Okay but if I make a voltage check with red probe on positive and black probe on negative I get 35.6V but I reverse I get -35.6V that indicates that the cables are rightfully installed right?


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