mysterious battery on 755, 770, etc

[Jefferson]

please take a look at the pic as it's worth 1000 words
(lower left corner, what appears to be 3 CMOS battery wrapped in tandem)

https://cafe.naver.com/tpholictalk/30629


Does anyone know what this battery does?

I'm mainly wordering

- what does it do?
- does the laptop function normally without it?
- does it leak and ruin the motherboard?

thanks!

[Thinkpad4by3]

please take a look at the pic as it's worth 1000 words
(lower left corner, what appears to be 3 CMOS battery wrapped in tandem)

https://cafe.naver.com/tpholictalk/30629


Does anyone know what this battery does?

I'm mainly wordering

- what does it do?
- does the laptop function normally without it?
- does it leak and ruin the motherboard?

thanks!

1) its a CMOS battery and I also believe a RAM-back battery(ie you put the machine to sleep and swap the main battery and this will keep it alive for a few minutes).
2) gives a 161/163 error on boot but otherwise yes,
3) Yes, but those *RARELY* leak in what Ive found. You should be much more concerned with the main battery leaking.

It is made up of 3 1.2v NiCD cells, basically a flat version of other NiCDs found in machines of a similar age.

[Jefferson]

1) its a CMOS battery and I also believe a RAM-back battery(ie you put the machine to sleep and swap the main battery and this will keep it alive for a few minutes).
2) gives a 161/163 error on boot but otherwise yes,
3) Yes, but those *RARELY* leak in what Ive found. You should be much more concerned with the main battery leaking.

It is made up of 3 1.2v NiCD cells, basically a flat version of other NiCDs found in machines of a similar age.

Thanks. The pic was for 755c but I also seem to recall a similar battery in 770 as well. As you know, 770 already has regular CMOS battery right next to the ram slot.

Does that mean 770 has a redundant CMOS battery system? After so many years, I can't imagine the NiCD battery still functioning at the designed capacity...

Thanks!

[Thinkpad4by3]

Thanks. The pic was for 755c but I also seem to recall a similar battery in 770 as well. As you know, 770 already has regular CMOS battery right next to the ram slot.

Does that mean 770 has a redundant CMOS battery system? After so many years, I can't imagine the NiCD battery still functioning at the designed capacity...

Thanks!

Same thing, its a standby battery just it isn't doing double duty with the CMOS settings. Thats handled by the other coin cell like the 701C.

[goldeneagle]

The NiCAD battery y'all are describing is the standby battery. It ONLY handles keeping the memory state intact when you suspend so you can swap main batteries. It has NOTHING to do with 161/163/CMOS. That's handled by the VL2020. Yes, it is rechargeable. No, you cannot use a CR2025/2032 (unless you theoretically put in a diode, so it wouldn't charge up). Replacement VL2020's are around $15. Not cheap, but they can last 5-15 years.