eli5; how do (built in) rechargeable batteries in a toothbrush or shaver last for ten years, but AA batteries die after 2 years of use?

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I don’t leave my shaver on charge, but my toothbrush is always in the charging holder, so it can’t be a difference cycled charging. I have a 20 year old toothbrush which I use for polishing jewellery, stick it on charge and it’s good to go.

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3 Answers

Anonymous 0 Comments

Your only using like 5% of the battery in there toothbrush or shaver at a time and then charging it again.

If the battery wears out to the point where it’s at 15% capacity you’ll never really notice if you charge it after every use

Anonymous 0 Comments

Charge cycles is a big thing, along with battery protection. Since massive batteries aren’t much of a worry, and it doesn’t take much to run them, the battery might tell you it’s dead at 30% capacity. Lithium rechargeables can easily take 1000 full charges, and are otherwise generally only damaged by overheating or running them all the way dead and leaving them.

I have a cheapo electric toothbrush, and even with daily use it takes months for it to tell me it’s dead. So I might only use 4-5 charges in an entire year. With 1000 charge cycles available, it’s not going to be the main issue.

AA batteries (I’m assuming you mean rechargeable) are probably being run down to minimum capacity. There’s no limiter to keep them from being overly discharged, and that causes degradation.

Anonymous 0 Comments

Good answers already. Also: purpose. One is built into a thing that is known to stand in a charger for long times. The other is very multi purpose and has to meet very different requirements. So it is a heck of a lot easier to make sure the specialized one doesn’t lose charge, when the other has to have a lot more possibilities…