Thinkpads Forum

I have a T-61 just about a year old. It has never left the docking station on my desk.

About 3 months ago, I got a message in the message center that the battery was bad and the wrong power supply was connected. The battery was almost dead, and the same supply had been connected for almost a year. Odd, no? Lenovo sent me a new battery and charger at no charge.

Once charged, the battery capacity was listed at 56.16 Wh and both the full charge and remaining capacity were identical. Now, two months later, the capacity says the same yet the full capacity shows 54.91 Wh and although it says I am 100% charged, the remaing capacity shows as 54.43 Wh.

Its almost like I am losing some of the capacity each month - or week.

Why would this be? Could the docking station or internal circuitry be defective? I would not think this should change in just 8 weeks.

Appreciate any insight.

Thanks.

~Bob

It's normal that the max capacity drop and after a couple of months it might drop a bit. So regarding your new battery i don't think there is anything abnormal about the 0.125 Wh drop.

Your old battery that ended up dead in a year might be a bit fast, but when you never really use the battery and leave the computer/battery in the docking station the battery don't last very long either. Even when you don't use the battery it will slowly discharge and when left in the docking it will be charged again when it drops below a certain level (i think it's about 96% by default). So in your case you will never really empty the battery and do a full charge since the power cable is always connected. Your battery drop a bit (to about 96%) and is charged to 100% again and this kind of charging usually kill the battery faster. It's more healty for the battery to let it run on battery sometimes and discharge the battery more then 4% before charged again. You probably heard it before that it's better for a battery to be fully discharged then let it drop a couple of percent and charge to 100% again. This is not the case for laptops batteries only.

Using the power manager you have a "Perform reset" option that could be a good idea to use sometimes. It will fully charge the battery to 100%, then do a full discharge before charged to 100% again. Doing this sometimes might extend the battery life. You should try to not use the computer during this process. This will also reset the max capacity field to show the correct value. When using the computer like you do and never discharge the battery this value might not show the correct value after some time.

Also you have a option under "Battery Maintenance" to set when the computer should start charging. In you case since you don't use or actually need the battery i would suggest setting the "Start charge when below" field much lower then 96%. Also set the "Stop charging at" some percent lower then 100% since that could help extend the life of the battery. Another option is to remove the battery from the computer since you don't need it if you leave the computer in the docking for 1 year without removal. If you remove the battery i think charging the battery to about 50% is the best thing to do before removal and not 100%.

Regarding the full capacity and the remaining capacity you won't see a 100% correct value here since there is no decimals. So if you have a battery with full capacity of 100Wh and the remaning is 99.8Wh i guess the correct value should be 99.8% remaing, but it would still show 100%. I'm not sure if it will show 99% when the capacity drops below 99.5% or if you have to reach 99.0% before it will actually show 99%. If you let the remaning battery drop a bit more i'm sure it will change to 99% pretty soon.

Thanks for a very informative post. I'll try changing some of the settings and see what happens.

~Bob