I did a search and couldn't really find an answer to this.

Someone told me that to preserve the overall lifetime of my battery that I should occassionally (once a week) disconnect it from the electric and let it run all the way down to about 5%. They said that this would help to keep the cells in the battery from one by one "dying" completely.

I figured someone here would be able to tell me if this is true and why. Is it like muscles? Use 'em or lose 'em?!

Thanks

Here is a quote from a manual:

What is battery conditioning or exercising?

When you intentionally discharge a battery down to a certain minimum voltage and then recharge it this is known as battery conditioning or reconditioning . It is also sometimes referred to as battery exercise. This is particularly important to reduce what some call the memory effect experienced using NiCD batteries if you habitually do not fully discharge them each time you use them. For NiCD batteries this must be done periodically, approximately every 10 charge/discharge cycles or so, or the batteries will begin to lose capacity. For NiMH batteries conditioning is not really needed to reduce any memory effect because that is negligent in this type of battery. However, reconditioning is very convenient for both NiMH and NiCD batteries because brand new batteries are not charged when you receive them and they must be charged and discharged three to five times before they reach their full capacity. In addition, occasionally conditioning rechargeable batteries helps to ensure that they give you years or service and save you as much money as possible, before you recycle them and get new ones.

True for NiCd batteries. Not true (but not harmful) for NiMH batteries. Not true and harmful for LiON batteries (which have a limited number of charge cycles).

Thank you very much. I didn't think to look in my manual!

And invaluable as I just looked up that I have Li-ION battery and this practice is detrimental.

Thanks

I'm not entirely sure that advice on the LiIon batteries is true. My thinkpad contains LiIon batteries, and it has a "battery maximizer wizard". It will adjust the charging threshholds and notify you when the battery needs to be discharged to improve charging capacity.

- cheapo

For a LiIon battery, i recommend whenever you are at your desk working on the power from the wall, that you simply remove the battery. The steady trickle charge from running on a full battery with the A/C adapter connected will reduce charge over time.

With my first battery within 8 months of keeping it plugged in the whole time with the battery in I went from ~3 hours to ~1 of battery power. Now I just remove the battery when I'm at my desk.

Be sure to put the battery in before unplugging the computer!

Well... the memory effect is in all kinds of batteries.
its worst in NiCd,
little in NiMH
and very little in the Lithium ones..

but its there.

I'd agree with fs2k2isfun that having a steady trickle and never discharging is going to wear it down. I've had that happen on a Toshiba I used previously. I'd also suggest that as long as you are using your laptop and discharging it now and again, the trickle seems to have less negative effect than if you always use the wall plug.