mapping X41 Tablet fuses - battery won't charge or show data

[MisterDNA]

In an older thread, I had a battery that wouldn't charge or run the system due to a bad fuse in the pack. I fixed the fuse (which seemed to involve a piece of solder tape with a resistive heater beneath it) and managed to prove that the system would run from battery, but wouldn't charge that particular one. I now have another battery which the system will operate from, but won't charge or show any data from. The power manager icon shows an X with both packs and comes up with something like "There is an error." in the upper-right status window of the battery tab.

Near as I can tell, there must be more fuses in the system than the two I found while working on it the first time and it's time to snoop them all out to find the bad one.

I just hope I'm not stuck replacing a motherboard.

[rkawakami]

This may not apply to your x41 (as it's based upon my experiences with the T23), but there could also be a loose/detached inductor on the motherboard which is preventing the battery from being charged. Well, that and also the battery charging IC could be defective. Most of the Thinkpad motherboards I've looked at use a Maxim IC (i.e., MAX1645 in a T41). Google the MAX1xxx part number to confirm it's a battery charging controller then look around that area for an inductor like the middle one in this photo:

http://www.kawakami-ca.com/ibm_t2x/t23_inductors.jpg

edit: A loose inductor will cause the lack of charging but it shouldn't affect the reporting of the battery's data. That does sound like a fuse or perhaps a battery charging IC problem.

[MisterDNA]

I opened it up and tested everything I could. I did find the charge controller and checked it out under a microscope. Nothing found.

I did find that my bad Lenovo-branded pack will report data until a charge attempt is made. The third-party one won't ever. I have a brand new Lenovo pack on the way right now so I'm going to wait until I can test that one in the machine.

The way I figure it, I either have a bad brand new third-party pack and bad original OEM pack and good motherboard or I have a bad motherboard and as many as three workable batteries.

On the bright side, if my motherboard really has a bad charge circuit, I will be able to attempt an upgrade to 1GB onboard RAM on that board while having a good one in my system. Getting the chips is the hard part. The BGA rework is no sweat.

[MisterDNA]

Okay, it was the battery packs, not the motherboard. I received the brand-new Lenovo-branded pack today and while it flashed the charge LED a few times then went dim, it came on solid and showed as charging.

The third-party pack is going back. I can't even use it.