ASUS Battery B31N1726 diagnosis

[PowerAmpFreak]

I had a ceramic cap failure in an ASUS G731 across the main system rail, and after replacing the cap, laptop works good. The only thing which is not OK, is there are no voltage on the battery-line.
So my question is: Can a direct short across the main system rail kill the battery?
Can I try to charge the battery with a current limited lab supply to diagnose the battery?

See the attached picture. The obvious black and red wires, but there are one white and one yellow aswell. Do I have to "enable" the battery terminals in any way through shorting any to minus or similair?

EDIT: I now could see in the service manual that the yellow and white wires are CLK and DATA for the BMS.

[PowerAmpFreak]

Is it common for a battery to fail when exposed to a shorted system rail?
The battery outputs zero volts after this. Is there a built in fuse in the battery that can be replaced?

[mon2]

Disconnect the battery. Meter in dc voltage mode.

Power on the logic board using only the power adapter.

Carefully measure the voltage to ground of each contact of battery connector on the logic board. Post each measurement.

Mostly interested in the voltage measurements of the scl and sda pins on the logic board.

[PowerAmpFreak]

+ pole on battery 0.2V
SCL and SDA has data (checked with a scope)

[mon2]

So the SMBUS lines on the logic board are not shunted due to an ESD event.

Now connect the battery pack and test the same lines again to see if these lines show any activity. Yes, it is possible that the BMS module on the battery pack has gone into a locked state. Confirm the details of the voltages and check if the battery + lines are suitable for charging of the battery pack.

[PowerAmpFreak]

Sorry but I misread your first post. The voltages above is with battery connected.

[mon2]

Locate the charger IC that is onboard. Perhaps will be the popular 'BQ' series by BenchMarq / Texas Instruments. Post the topside markings of this component. While still possible that the battery pack is in a locked state, the battery linked mosfets should also be reviewed for possible damage. If the charger IC is the BQ series then the mosfets will be N-channel type.

The gate pin of each such mosfet should be higher than the voltage being passed between the source / drain pins to enable.

In Windows, does the battery get detected? Does the battery charge graphic show in Windows?

Your scope may offer a SMBUS logic analyzer (LA) feature which can be used to monitor the SMBUS traffic which can reveal if the BMS is locked or not.

[PowerAmpFreak]

Attached the schematic for the charger IC.
It's typical sync buck topology.
In Windows, the battery symbol says battery fully charged.

[mon2]

Be sure this battery connector is being plugged in the correct direction onto the logic board. Another thread on this forum had a similar fault and was due to the wrong keying of the connector. Suggest to test with a known good battery (Amazon?). If the battery is removed, what does Windows report?

[PowerAmpFreak]

The connector is ok, the battery has been working well before. And it's not possible to reverse the connection (poka yoka key). When battery is removed Windows says the same as with the battery, fully charged 100%.
I guess it's the battery which is in charge of telling charger IC to start charge?

I will try another battery soon.

[PowerAmpFreak]

New battery tested and everything works as expected.
So the shorted system rail somehow caused damage to the battery smbus / bms controller.