Thinkpads Forum

I just plugged my battery back in and started using my laptop with the ac adapter plugged in, it didn't respect my custom battery charge thresholds of 20/40 and started charging it up. I have all the latest software on my Thinkpad T61.

Does anyone have any ideas?

Thanks.

The notebook forgets battery charge thresholds if you remove AC power and the battery. To prevent it from starting to charge after having removed and re-installed battery, don't connect to AC power when booting first time after having re-installed the battery, just use battery power. When Windows is fully started, the computer will remember battery charge thresholds. Then shut down the computer and connect to AC power. Now it will remember the battery charge thresholds that have been set.

Thank-you for the advice. That's really quite annoying. It should remember the thresholds for a particular battery, since it knows the serial number and everything.

Does the 20/40 help maintian long battery life when connected to commercial power for long periods? I ahve been trying to determine how to set this up, and most of the time mine is run on commercial power and occasionally on battery. Any advice would be appreciated.
Thanks!
jplock

As far as i understand, the lifetime of a lithium ion battery is determined by the number of charging cycles. That is, it can go through a certain number of charging cycles, and then it will die. So, as long as a notebook is connected to AC, i would start charging when the battery is practically empty (1%) and stop charging at 80%. I suggest stopping to charge at 80%, because having to keep a full charge makes the battery deteriorate faster.

Whenever you're going to travel, you can change charge level thresholds to start charging at whatever percentage you consider to be the minimum that you want to hit the road with and stop charging at whatever level that is necessary to provide the amount of operating time that you need. If you need long operating times without AC power, it doesn't make much sense to stop charging at 80%, just in order to save the battery. Under such circumstances, i would charge to 100%. Also, for travel, i wouldn't stop charging at under 80%.