BQ40Z80: BQ40z80 not detecting on certain connection process

OverAgent712

Part Number: BQ40Z80

Tool/software:

Hello,

I am facing issues while making a battery pack of 4S BMS designed in house.
Scenario 1: connect the cell terminals of the battery then the power through connector, it works no issues.
Scenario 2: connect power then cell terminals it doesn't work
Scenario 3: connect cell terminal then positive/negative and then the remaining one, doesn't work
The cell terminal doesn't power on the board, the last cell isn't common or net tie with the pack +. This is made intentionally.
Is there a sequence on how to connect it ?

3 months ago

0 Alan Frias 3 months ago

TI__Mastermind 25355 points

Hello,

There is no order in the way you are supposed to plug in your cells, typically you would plug in your cells to the Pack +/-. Please reference the EVM documentation to setup your board.

EVM:
https://www.ti.com/lit/ug/sluubz5/sluubz5.pdf?ts=1747943079385&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ40Z80

Thank you,
Alan

0 OverAgent712 2 months ago in reply to Alan Frias

Intellectual 460 points

Hello,
Sorry for the delay in the response.

Observations :
1. No sparks comes from the XT60 connections.
2. While directly connecting the battery to the board a light spark is obeserved. Will this cause bq to shutdown ?
or is there a protection in it, which can be disabled ?

Because of that spark the bq is not detecting it after wards, how to resolve it ?

0 Alan Frias 2 months ago in reply to OverAgent712

TI__Mastermind 25355 points

Hello,

If you are seeing a spark observed within the board it is hinting that there is a load on your system. Typically the battery gauge controls the fets and remain open when no cell is connected. A spark does have the capability of damaging the board and we recommend minimizing any sudden sparks

Thank you,
Alan

0 OverAgent712 2 months ago in reply to Alan Frias

Intellectual 460 points

Hello,
Yes, there is load but it is in mA. This was not observed previously on 6s design. The design is same for both except for the cell connectors. So we are puzzled with this new behavior, The spark is very light but present. Are there any suggestion to reduce it ?

0 Alan Frias 2 months ago in reply to OverAgent712

TI__Mastermind 25355 points

Hello,

If you are seeing a sparking than something would be hinting to a short happening. Please review your schematics to that there is no components seeing a load pre the fet path.

Thank you,
Alan

0 OverAgent712 2 months ago in reply to Alan Frias

Intellectual 460 points

Hello,

Yes the schematics was verified from the forum itself. There are no such shorting in the PCB between the positive and negative terminal and there were no such issues in 6s with same schematic and layout

Power management

Power management forum

BQ40Z80: BQ40z80 not detecting on certain connection process