Battery In or Battery Out?

[First Light]

T42p with 9 cel Sanyo battery (fits fine BTW) and have a question.

If I operate the unit on A/C power most of the time do I need to/should I leave the battery installed? Does it make any difference?

[hausman]

Lithium batteries deteriorate from heat. When you leave a fully charged battery in your AC-powered system, you accelerate that process because of the heat thrown off from the CPU, memory, HDs, etc. You have to decide whether the UPS value of an always-inserted battery is worth the cost of reduced battery life.

IBM includes a fair bit of information about the care of batteries in their documentation. Take a few minutes to review that material. Also, see http://www.batteryuniversity.com/parttwo-34.htm

[Daniel]

If you're plugged in most of the time, set your Battery Maximizer to start charging at 30 percent. Discharge the battery partially 40-50%, and just leave it like that.. You'll have the advantage of long battery life and a UPS. I don't see heat affecting the battery much on a T42P. The battery sits fairly far away from the HDD and CPU and stays at room temperature. If you'd like MAXIMUM battery life/storage, discharge it to 40% and store it in a Zip-lock bag in the fridge.

[Daniel]

The link Hausman posted is why I'd advise discharging the battery and/or storing it in the fridge.

[jdhurst]

Once the battery has been used, it starts to die from time used. I don't worry about leaving batteries in ThinkPads with up-to-date power management systems and drivers, because the heat does not seem to affect them more than just normal usage. And more than once, power has died at some inconvenient time, and the battery is *so* useful at those times. ... JDHurst

[Greg Gebhardt]

T42p with 9 cel Sanyo battery (fits fine BTW) and have a question.

If I operate the unit on A/C power most of the time do I need to/should I leave the battery installed? Does it make any difference?

Just leave it in and enjoy your laptop. In a couple of years you might have to replace the battery IF you still have the laptop and have not upgraded.