lm317 help

timmeh87 · Post by **timmeh87** » Sun Apr 09, 2006 12:28 pm

hm. interesting. so it is possible to just hook batteries up to certain wall adapters...

that one is rated at 300mA. if you find a similar one, id have to assume you could use it to charge your batteries.

i wonder what happens when they are fully charged though. this might be one of those "you have to know when to take off your batteries or else they will get overcharged and heat up" kind of chargers.

edit -
actually. i think you can just find any 12v wall adapter, and use the formula

time = 1.2 ( pack capacity / adatper current rating)

and then yes, you do have to time it yourself and manually stop it from overcharging your pack.

this would probably work regardless of the voltage of the adapter too, as long as it was 3 or so volts higher than your packs voltage. (AND IT OUTPUTS DC)

vskid · Post by **vskid** » Sun Apr 09, 2006 5:07 pm

This is better than buying a charger, I already have 12v adapters. My guess is that up to 15v would be fine on a 7.2v battery(I'm not sure), since my charger for 9.6v batteries outputs 19v. So do I hook the + from the adapter to the + on the battery or the - on the battery?

timmeh87 · Post by **timmeh87** » Sun Apr 09, 2006 6:17 pm

+ to + and - to -

vskid · Post by **vskid** » Mon Apr 10, 2006 4:59 pm

I charged the battery with a 12v 800ma adapter, and an hour latter the adapter smelled like burnt plastic and the batt. was at 8.4v. It still works.
Fully charged, the pack lasts about 35 min, then the screen goes funky til the backlight gives out. I'm gonna buy some LEDs latter so I can mod the screen.

timmeh87 · Post by **timmeh87** » Mon Apr 10, 2006 6:17 pm

just remember - dont leave the batteries on the charger too long. if they feel hot, thats too long.

vskid · Post by **vskid** » Mon Apr 10, 2006 7:22 pm

The battery was cool when I took it off, I'm more worried about the wall adapter.