Yet another 701c battery question

[TrowaBarton]

Hello all, I've recently acquired a 701c in good working order except of course its battery.

I have the nimh version and found sites online that detailed their AA replacement process. My battery had minimal leakage inside and the contacts on the controller are all fine so I followed the patterns and wired everything up, I'm getting the expected 10.5+ volts when measuring contacts 1 and 4 (batteries came precharged).

Both before and after the procedure the thinkpad itself says "Not Detected" for the battery status, I mostly ignored it before thinking the cells were too far gone to be reliably connected to each other anymore. The machine cannot power on with just the battery and when plugged in it still doesn't seem to recognize that the battery is attached.

The contacts inside the machine also appear to be in good working order and I'm currently waiting for a fabled Torx T1 to arrive before I can delve deeper inside. Does anyone have any ideas on what I should look for? Any good way to tell if the Dallas chip is still functional? I'm measuring ~1V across two pins. Could the bottom board in the machine have failed in some way to prevent proper battery detection?

I'm not getting cmos errors and it doesn't appear to be leaking but is taped down right in that area so I can't fully rule it out yet.

[BillMorrow]

hello and welcome to the forum..

first thing, be careful with the T-1 driver AND those tine screws..
when reassembling, be sure the holes are aligned and do not overtighten..
you can easily strip the screws AND easily twist the end off the torx driver..

ok, it has been a LONG time since i was inside a 701C..

as i recall (without looking at a 701C right now) that there is a small board inside with contacts that mate up with the battery when it is installed..
just be sure those contacts are bright and clean..

you say you are not getting the CMOS errors on startup..?
not possible unless the CMOS battery has been previously replaced within the last about 10 years or so..

are you sure everything else is ok..?

lastly, if you wish you can send me that battery and i'll plug in into several 701C's and see if one or all of them "see" the battery..
and i'll send it back, of course..

ok, this is lastly:
i DO have NOS system boards, batteries (all dead, i'm sure) and NOS keyboards..

[TrowaBarton]

That is correct, the CMOS appears to be functioning, date and time are properly recorded and no POST errors. The machine came with a working install of Windows 98.

When I shined a flashlight innside the contacts appeared to be fine but the ground contact on the battery did have small amounts of battery acid along the edges, perhaps the contact in the system needs a good scrubbing but it didn't appear discolored.

My other current issue is that I attempted to use regular AA batteries instead of opting for more expensive industrial ones with soldier tabs, any tips on how to keep the soldier properly attached? Connections to the positive terminals especially seem pretty hit or miss and sometimes when trying to hold the case together tightly it was enough force to break connections.

I certainly wouldn't want to ship you the battery for testing as I'm not overly confident it would stay functional in transit. My goal was that once I had confirmed it was working I was going to superglue it back together as other people have. (Which sounds like it would make it even harder to replace them again in another decade...)

When you say "NOS" what does that actually stand for?

[rkawakami]

"NOS" = new, old stock. It refers to material that has sat on the shelf in a warehouse since it was manufactured eons ago . To be truly valid as NOS, it must still be sealed using the original factory tape. For non-consumable parts (motherboard, keyboard), this is not too much of a problem. With batteries however, they degrade over time even if they're not used. Which is why Bill is probably sure that they are dead by now.

[TrowaBarton]

Thanks for the definition, I'd almost be afraid to even open those battery boxes. At this point I'm going to hold off on troubleshooting the battery further until I can get a good look in the machine, perhaps also try it with the bottom bezel removed to ensure the contacts are... well... making contact.

Currently plotting to triple boot it dos/Win 3.11, NT4, and 98, I've done similar things before so it should go simply enough, I have an R52 and some T43p if I need cdrom/usb floppy stuff while waiting for a PCMCIA cdrom and the correct cable for floppy. There are a few auctions on ebay for the floppy drive, and it came with two cables, but neither were the correct fru for the 701c (04H6916). ACS parts is selling the cable for $20 and I attempted to make an offer for $10 but haven't heard back from them yet, not sure if they'll even respond.

I also have an 3CXFE575CT ethernet adapter coming, I believe I was able to find dos/3x drivers to support it unlike the ton of 589 based cards floating around ebay, this one is also the X Jack type so no dongle to worry about!

[TrowaBarton]

Alright, I've gotten the thing apart and got the "top system board" out, 41H7188 is printed on it. The contacts look fine on the battery side of things but the backside there is a lot of damage to them, I suspect a previous cmos battery leaked and ate away at the back side of them. I attempted to test for continuity at the soldier joints and 3 of the 4 pins didn't respond...

04H8343 is also the FRU used in the HMM so I suspect mine is a later subpart.

BillMorrow were either of these perhaps one of the parts you had available for purchase?

[TrowaBarton]

Well a couple updates, I got a replacement top board and cleaned off the standby battery leakage and it works, I can run the machine from battery, but it won't power up unless the power cord is plugged in since it thinks the battery is dead. The battery gauge displays 0:00 0% and the bios says Charging, screen seems to power off after 10-15 seconds of idle regardless of what settings I tweak/enable/disable in the bios.

While putting the new top board in I decided to have a lil look at the cmos battery.... it uhm.... looks like its the original one still..... I measured 2.9V from it which is all around baffling. Unless someone is a wizard at soldering the solder looks untouched, smooth, flat, well here have a picture: original battery?
I suppose it could just be an exact match soldered on recently, it looks a bit angled.


I also snagged a 701cs on ebay that needed a new cmos battery so now that's working, its top board wasn't completely destroyed and the battery behaves the same way in that machine. This one had the nicd battery instead, but I believe its controller would be interchangeable with nimh models right?

If not, I'd like to try and hunt down possibly NOS nimh batteries and see if they may have more gracefully failed than worn out ones.