Thinkpad 380XD oddball charging behavior

[MSQ90]

This issue had been manifesting where I would insert the main Li-ion battery pack and the charging system would kick in, but emit a faint high pitch whine for a few seconds then stop, only to seemingly 'retry', and sometimes there would be an outright buzzing sound from the system when I start the 380XD. Within windows, the battery pack is considered to be charging, but is stuck at 80% and the system dies whenever the AC cord is pulled. I thought at first the battery pack was bad, but after purchasing a new pack, the system still refuses to run on battery power. Does this have to do with the motherboard? Or the powerbrick?

[axur-delmeria]

High pitched whine --> Coil noise, perhaps?

It's probably the power/charging circuit. I don't know if it's integrated to the system board, or a separate daughter board, as I've yet to own or dismantle a 380 series Thinkpad.

[MSQ90]

High pitched whine --> Coil noise, perhaps?

It's probably the power/charging circuit. I don't know if it's integrated to the system board, or a separate daughter board, as I've yet to own or dismantle a 380 series Thinkpad.

Looks like the 380XD has a DC/DC daughter card, from what the Service manual states. I did record sound of the system making the noise while attempting to charge the battery.

[danikayser84]

I think if the battery is bad/defective (shorted out, bad cell, etc.) it will likely damage the charging circuit on these machines (I have a 380ED with a similar issue, I usually leave the battery out or put tape over the terminals since I don't really use it with battery anymore)

[MSQ90]

I think if the battery is bad/defective (shorted out, bad cell, etc.) it will likely damage the charging circuit on these machines (I have a 380ED with a similar issue, I usually leave the battery out or put tape over the terminals since I don't really use it with battery anymore)

That makes sense, since Clint (Lazy Game Reviews) just uploaded a video of his 380XD restoration and he mentioned the strange whining sound from the battery area. So I could probably salvage a non functioning 380 series DC/DC daughter board and see if replacing it would solve the problem, if not, could be a separate circuit that could be replaced by other parts.