How to pro­long lithium-based batteries

This is the most use­ful arti­cle I’ve read in ages. The whole Bat­tery Uni­ver­sity site is great, but this page in par­tic­u­lar is pure gold.

Dave’s lap­top bat­tery is fried… just over a year old, and it only lasts about 20 min­utes. My lit­tle Acer TabletPC has two 2-hour bat­ter­ies, and I’ve just realised that the info I got from Acer about how to look after them is bad, bad, bad, and I’m gonna have to change my usage habits if I want to get the full 2 — 3 years out of ‘em.

If you can’t be both­ered read­ing the whole arti­cle, here’s the impor­tant summary:

• Don’t leave your lap­top plugged in to AC power with a fully charged bat­tery. It’s the heat that kills ‘em, so don’t leave them in hot cars either.
• If you’re not using them, it’s best to store bat­ter­ies at about 40% charge, and as cool as pos­si­ble. Never store them for long peri­ods com­pletely dis­charged or they might not recharge at all.
• It’s bet­ter not to fully dis­charge lithium-ion bat­ter­ies — power “top-ups” don’t hurt them as they don’t have mem­ory like nickel bat­ter­ies. How­ever, if you never fully dis­charge the bat­tery, the “power remain­ing” gauge becomes inac­cu­rate. A full dis­charge every 30 or so charges will take care of that.

Hmm… I’m off now to label my two bat­ter­ies and start keep­ing track of each charge/discharge. There’s noth­ing worse than run­ning out of power when you’re no where near a power point!

I can’t help think­ing that in 10 years time I’ll be telling sto­ries about how we used to have lap­tops that only lasted three hours. Give the kids some­thing to laugh about.