Thinkpads Forum

When my ThinkPad 385 XD boot up, it occasionally asks for me to fill in the current date and time. Is this a sign that an internal battery is going bad and needs replacement? Or something else that has to be fixed?

skytrain wrote:Is this a sign that an internal battery is going bad and needs replacement?

Yes. Generally referred to as the CMOS or backup battery. If you don't already have a copy of the Hardware Maintenance Manual, you can download a copy from here:

http://www-307.ibm.com/pc/support/site. ... FAN-3T5R74

Leafing through the manual, page 62 has the instructions on how to replace this battery. Basically, open up the memory panel/door and there it is.

OEM battery is CR 2330, 23mm, 3 Volt, 265 mAh. I couldn't find anyone who had one, including Radio Shack, but found and replaced it with CR 2325, 23mm, 3 Volt, 165 mAh, which works fine. The computer techs said just do not use one with a higher amperage than the original. I will continue to look for the OEM replacement.

I would tend to disagree with the techs you quoted. The amperage rating for the battery is an indication on how much current it can deliver over its lifetime. Therefore, lower mAh = lower run time. Since the CMOS battery provides the voltage and (mainly the) current needed to keep the configuration memory alive and because that memory only draws a few microamps, drastically lowering the current capability (in this case a reduction of about 40%) means that instead of the battery lasting 5 or 6 years, you may have to replace it in 3 or 3 1/2.

Thank you very much for the information...I will keep an eye out to monitor it. This is one of the best forums I have ever used.

The only reason I used that particular battery was that I had it on hand and no one was able to find one that was anywhere close in size.