Hello. I have an HP 15-EF series laptop that works fine when it is plugged in with the AC adapter. The initial issue was that Windows was reporting that no battery was installed, as was the BIOS, and upon removing power, the system would immediately power off. I bought a new battery, but the system behaves the same, with the exception that it does not power off upon disconnecting the AC adapter. Before realizing that the system stays powered on after removing AC with the new battery, I tested all around the charging circuit for shorts and voltages, and everything looked normal to me, including the BATTDRV signal from the BQ charging IC, which I believe is what switches the MOSFETs on to allow the battery to run the computer. That makes sense given that it does stay on when disconnected from power.

If I try to power the laptop on without the charger, it blinks the LED 3 times and does not power up. That code indicates that the system is reporting that the battery is drained and not accepting a charge.

My best guess at this point is that there is something wrong with the BQ charging IC as it relates to communicating with the battery via the SMBus. While I am fairly confident in my ability to remove and replace small capacitors and resistors, I'm not sure about a tiny 20 pin IC.

I also saw some info online about a possible firmware issue causing similar behavior, but I updated to the latest and it still behaves the same way.

Also, given how it is behaving, my assumption is that once this new battery drains, it will no longer work at all on battery power, because I don't think the system is charging it.

Does anyone have any suggestions other than the BQ IC, or do you also think that is likely the issue?

Thanks.