Keep Your Laptop Battery Meter Accurate

Since I use a laptop as my main computer, I keep it plugged in 24/7. But when I take it on the road, I notice that my battery meter shows nearly empty even when it still has loads of power. Can that be fixed?

I’d guess it’s a NiCadmium (NiCad) battery, and in all likelihood it needs to be recalibrated, which is easy to do. Leave the computer running on the battery until it runs out of power and shuts off automatically; then recharge it fully.

If your battery is a Lithium Ion (LiIon), which most newer laptops use, the problem is more difficult to solve and you should take it in for repair. In any case, avoid running a LiIon to empty because it shortens its life.

There’s loads of misinformation about rechargeable batteries. Let me clear up some of it. Before LiIons were introduced, the dominant laptop battery was NiCad, which suffered from a shortcoming called “memory effect.” If you continually recharged a NiCad before it was completely empty, it eventually “thought” the full charge was where it was just before you recharged it and stopped recharging fully. As a result, users were advised to run NiCads down to empty every couple of weeks and then fully recharge them.

The new LiIons, which hold a larger charge than NiCads, have their own shortcoming: They don’t store well. They generally last two to three years whether used or not—and their clock starts running right after they’re manufactured; so never buy a used LiIon. Their lifeline is further compressed each time they are run to empty. So, in general, it’s best to keep them fully or at least partly charged.

If your LiIon-powered computer can run plugged in without the battery, consider such a setup while in the office, but be sure to use a good surge suppressor. To maintain the LiIon’s life, charge it to about 40% and store it in a cool place (about 60F); higher temperatures hasten its demise.