Protanium battery - controller circuit?

[RocketDane]

Hi all

The electronics in my battery do not work properly and I am looking for a circuit diagram or any other info on the battery. It is a Protanium BP-L2410SH1 29,4V DC 10Ah and the board has this text on it: 7SGHP-VERD-20070928

Without a load there is full voltage on the output but when a load is connected the voltage drops to zero. Measurements inside show that the electronics charge the cells and distribute the voltage nicely between the cells and they can be discharged with a good current by wires connected to the inside. But the fets do not open for the full current when I try to discharge it normally. Apparently the fets are not instructed to open but finding out why could be a real pain so any help will be very much appreciated.

This is what the board looks like if anybody recognizes it?


We have tried shorting where it says "reset" but to no avail.

Thanks

RocketDane

 

[Deleted member 4366]

One or more of your cells is probably nackered. You need to measure the voltageof each cell between the adjacent pairs of the 8 coloured wires (black to blue, blue to green, green to red, red to brown, etc) while the battery is under load to see if any sag down to 3.1v, which will seitch off the output.

The board is a standard 7-cell BMS. From what you've described, it's probably working properly.

 

[RocketDane]

Thank you for the quick reply.

If there is a bad cell it seems a bit odd that we got 5-10 A out of the battery with a constant voltage of 28 V. But you are right we did not measure the individual currents while under load. Will do.

Can you elaborate on your comment "standard 7-cell BMS"? Is there documentation for this somewhere? Cheers.

Best
RocketDane

One or more of your cells is probably nackered. You need to measure the voltageof each cell between the adjacent pairs of the 8 coloured wires (black to blue, blue to green, green to red, red to brown, etc) while the battery is under load to see if any sag down to 3.1v, which will seitch off the output.

The board is a standard 7-cell BMS. From what you've described, it's probably working properly.

 

[Deleted member 4366]

Here's a schematic for a 10 cell one. Yours is the same but with 7 cells. It's the cell voltages you have to measure under load, which is what the BMS os doing.

 

[RocketDane]

Well, the cells seem all right. Here are values from measurements under load:

Cell 5A load 10A load
1 3.85V 3.71V
2 3.85V 3.68V
3 3.80V 3.71V
4 3.85V 3.68V
5 3.87V 3.70V
6 3.86V 3.80V
7 3.86V 3.69V

Which leads to the conclusion that the BMS is likely at fault for not letting all this lovely electric energy flow to the motor. But how to fix it?

Best
RocketDane

 

[Deleted member 4366]

As a temporary measure, you can jump the BMS output controls by bridging the B- thick black wire to the P- thick black one.

It's probable that it's shutting down for a reason and trying yo protect the cells, so be careful. Without the output controls there will be no l9w voltage control, so use the LEDs on your throttle/panel to figure out when the battery is empty. Your controller should still protect it too.

It's possible you have a faulty connection in one of the cell voltage sense leads.