BQ76940: Problem with BMS

Rajesh Gupta69

Part Number: BQ76940

Dear Team,

We are making the Li-ion Battery Pack (48VDC) by using the BMS controller having part: BQ7694006DBT (TSSOP-44 Package) .

In our design we are using 14 nos of cells connected in series with every cell voltage 3.6VDC (Nominal) . We are facing following problem with this BMS Controller :

In some of the battery pack , Cell C6/C7/C8 gets discharge below 1.0VDC when BMS is in sleep mode .

Please suggest if any thing is missing in circuit diagram which may leads to this problem.

Attached Schematic.In1.pdf In2.pdf

Best regards

Rajesh Gupta

over 6 years ago

0 Vish Nadarajah over 6 years ago

TI__Expert 6085 points

the schematics appear clean and correct. I'm to suspect of the device actually NOT in SLEEP. If the middle group is the issue, when you command the device into SLEEP, if the CAP2 and CAP3 are also collapsing. Also change the caps in between on the C6/C7/C8.

0 Rajesh Gupta69 over 6 years ago in reply to Vish Nadarajah

Prodigy 20 points

Dear Vish,

Thanks for the input.

Can You help to elaborate more on the changes we have to make to resolve the issue?

Best regards

Rajesh Gupta

Power management

Power management forum

BQ76940: Problem with BMS