# Battery Re-charge rates **URL:** \ **Category:** Factual Questions\ **Created:** [February 9, 2007, 11:36am UTC](https://boards.straightdope.com/t/battery-re-charge-rates/391481 "2007-02-09T11:36:13Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [February 9, 2007, 11:36am UTC](https://boards.straightdope.com/t/battery-re-charge-rates/391481/1 "2007-02-09T11:36:13Z")
Do batteries recharge at a uniform rate over time? Or do they take in the bulk of their capacity in a relatively short period, and take more time to “top off” the last few per cent? Or something else? As a bonus, if anyone knows, if my iPod battery is spent, and I only have 30 minutes to run a charge, how long will it play – approx? What if I have an hour to charge? ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [February 9, 2007, 12:13pm UTC](https://boards.straightdope.com/t/battery-re-charge-rates/391481/2 "2007-02-09T12:13:19Z")
Speaking only from my iPod experience, not from an electronics background. An hour charge will give you about 80% charge. So yes, It charges faster the less charge it has. A half hour charge is normally enough for my wife’s 5 hour shift (on an old Nano) ---
**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\ **Post date:** [February 9, 2007, 3:38pm UTC](https://boards.straightdope.com/t/battery-re-charge-rates/391481/3 "2007-02-09T15:38:48Z")
No electronics background here either, but topping up my laptop’s battery from 90% to full takes about as long as going from 50% to 90%. I think that might be also due to the fact that the charger slows down the charging rate as the battery is charged, to avoid overheating and other problems, but it’s really a WAG. I’m sure that the charger has as much to do with it as the battery, though, because you can buy “fast” chargers which work with “standard” batteries. ---
**Author:** ![Aserrann](https://avatars.discourse-cdn.com/v4/letter/a/82dd89/32.png) [@Aserrann](https://boards.straightdope.com/u/Aserrann)\ **Post date:** [February 9, 2007, 5:09pm UTC](https://boards.straightdope.com/t/battery-re-charge-rates/391481/4 "2007-02-09T17:09:42Z")
I assume it depends on the battery, but I’ve seen several chargers that state they fast charge to 80%-90%, then trickle charge the rest, which means they take about an hour for the first 80%, and a few more hours for that last 20%.