Well, this is a bit of a shocker and no mistake. I've been happily toddling along through life under the impression that the way in which I charge my iPad will prolong the life and efficiency of its battery. Now, however, it seems that my habits may be having the opposite effect (sad face).
This all started a few days ago when I evaluated some iClever USB chargers (see I Love My 4-Port Beast of a USB Charger).
As part of that column, I made the following comment:
I don’t know if this is still true, but I remember being told that the batteries in things like iPads can exhibit a sort of “memory” effect that impacts their charging ability — also, that it's best to let the charge fall to around 10% and to then recharge to 100% in a single sitting.
I've informed my wife (Gina The Gorgeous) and my son (Joseph The All-Knowing) as to this charging philosophy on numerous occasions. As with most things, however, they haven’t paid the slightest attention to what I've had to say. On the contrary, they tend to charge their devices willy-nilly whenever they happen to come into close proximity with a charger and the mood takes them.
The embarrassing thing is that — and I'm saying this in a hushed whisper with a brown paper bag over my head — it turns out that their way of doing things may actually be better than mine. The way in which I discovered this niggling and nagging nugget of knowledge was when EETimes community member Roger46 posted the following comment to my USB charger column:
As a calculator design engineer in the 70s, I well remember memory effect when we were using NiCad rechargeable batteries. That and a rather high self-discharge rate. Lithium batteries seem to have moved past that era, fortunately (see this discussion about prolonging the life of modern batteries on BatteryUniversity.com).
My personal experience seems to agree with their suggestions. My wife and I have had similar phones in the past. She tended to use hers until it ran down, while I liked to keep mine recharged as often as possible. She replaced the battery pack in one phone twice while I was still on the original with identical phones…
I immediately bounced over to see the discussions in question. Arrgggh! It seems that limiting oneself to partial discharges reduces stress and prolongs battery life. In Table 2 — Cycle life as a function of discharge — we discover that a 100% DoD (depth of discharge) results in only 300 to 500 discharge cycles; a 50% DoD offers 1,200 to 1,500 discharge cycles; and a 25% DoD provides 2,000 to 2,500 discharge cycles.
To read the rest of this article, visit EBN sister site EE Times.