Submitted by Dakens2021 t3_10jgsbh in BuyItForLife
I've tried so many different kinds of these and never found one which lasts. I'd like to put a stick up light in a bay window at my house, but don't want to go through wiring and drywall and everything to hardwire one. It seems like with LED technology you should be able to power an LED light for a long time on a battery, but I haven't found one like that. Can anyone recommend a stick up LED light which just lasts years on one battery?
BoilerButtSlut t1_j5kc5q3 wrote
You won't find one, at least unless you have it really really dim.
A single dim LED takes about 5mA to light. A single li-ion cell is about 3600mAh. Do the math and that's 720 hours before the battery needs to be charged. At 8 hours a day that's about 90 days.
You would have to get a large battery pack for it to last years, especially with multiple LEDs and high brightness. Or you could light it with like 1mA but it will be so dim that you would only see it if looking straight into it.
One avenue you could try is having a small solar panel with battery. That lets you get away with a smaller battery pack since you'd be recharging it almost daily. That depends on the location and setup though.