3000 N100 - date and time are getting reset, CMOS battery empty?

[BigCatAndy]

Hello,
recently I bought one Lenovo 3000 N100 (without a battery), and have following issue with it: when it remains longer disconnected from the power supply, it doesn't start at first button press. At the second one it starts, but says "Time and date are not set, CMOS checksum is bad". When I go to BIOS, it says "01/01/2015". I suppose, the BIOS battery is empty. Is it possible to replace CMOS battery (like in thinkpads)?

regards,
Andrey

[axur-delmeria]

Took a quick look at the N100 HMM https://download.lenovo.com/ibmdl/pub/p ... 553_03.pdf but I can't seem to find a replaceable CMOS battery. It's possible that the CMOS battery is a rechargeable one that's soldered to the system board.

Confusingly, the Symptom-to-FRU Index mentions:

0270
Real time clock error

1. Charge the backup battery for more
than 8 hours by connecting the ac
adapter.
2. Replace the backup battery and run BIOS
Setup Utility to reset the time and date.

#1 proves that there's a rechargeable backup battery, but #2 implies a removable battery but is never mentioned in the disassembly section.

It's likely that the main battery is needed to keep charging the backup one in order to keep the date and time.

[BigCatAndy]

Took a quick look at the N100 HMM https://download.lenovo.com/ibmdl/pub/p ... 553_03.pdf but I can't seem to find a replaceable CMOS battery. It's possible that the CMOS battery is a rechargeable one that's soldered to the system board.

Confusingly, the Symptom-to-FRU Index mentions:

0270
Real time clock error

1. Charge the backup battery for more
than 8 hours by connecting the ac
adapter.
2. Replace the backup battery and run BIOS
Setup Utility to reset the time and date.

#1 proves that there's a rechargeable backup battery, but #2 implies a removable battery but is never mentioned in the disassembly section.

It's likely that the main battery is needed to keep charging the backup one in order to keep the date and time.

Thanks you very much for the hint. I found on the Internet, the type of battery - fixed or replaceable - depends on the type of the laptop.
Going to put the laptop on the power over the night.
Regards,
Andrey

[BigCatAndy]

Thanks you very much for the hint. I found on the Internet, the type of battery - fixed or replaceable - depends on the type of the laptop.
Going to put the laptop on the power over the night.
Regards,
Andrey

Update: CMOS battery keeps the date and time after keeping my laptop on the AC power for 8-10 hours.

Cheers,
Andrey