Need advice around batteries / BMS


Thread Starter


I'm wanting to use a laptop battery and charger to power a project, I've got this HP stream one with LG cells, I'm not too familiar with battery setup and was wondering if anyone knew if the board that's built into the pack is a BMS, and if so can I just apply power to charge, as I said I would use the original charge? I can see that there's a thermistor on the board so that at least accounts for 2 of the wires that aren't red or black but I'm not sure what others will be

Any advice greatly appreciated.

Here's what I'm looking at.... hopefully it helps.
The circuit in the battery pack or in the "charger" is not a charger circuit. Instead the circuit prevents the battery from catching on fire if it is charged or discharged wrong and the "charger" is a power supply for the charger circuit that is inside the laptop. The battery is probably a lithium type so each battery cell has its own wire so it can be charged and measured separately from the other cells.

I use laptop cells (with the circuit cut away) in a portable vacuum cleaner that had its old Ni-Cad battery fail. Then I charge it from a circuit that I made which is almost a proper lithium charger circuit.

If you charge or discharge a lithium battery wrong then the resulting explosion and fire will be spectacular.
Yeah I've tried connecting the charger and the 11v cell pack is up to 20v now (was discharged) so looks like your right, although the cells didn't get warm, I looked up the Texas instruments chip I saw on it and it seemed to imply charge management but not specifically or that I could understand anyhoo, are there any off the shelf circuits I could buy to manage the 3 cells
Very dangerous.

Anything above 12.6 volts risks explosive failure.

I'm frankly astonished that at 20V you didn't have a pyrotechnic failure.