# 12 Volt Battery

Discussion in 'Electrical' started by cromartie, Jul 8, 2011.

1. ### cromartieNew Member

For all you electricity gurus out there ...

How long will a 12 volt, 12 AH battery last with a 55 watt halogen headlight and a LED tail light setup?

Plan on charging each night when I get home with a wall a charger.

Thanks.

2. ### Al.FishermanActive Member

Until it looses its charge. Hook one full charged battery to the 55W headlight, the battery won't hardly know about the LED. And see how long it will run to where you think it needs charge.
Actually there is a formula to figure it out, can't remember it, was over 46 years since I've used it.

Found this...
12volt 7.5H battery. 100W bulb

watts = volts x amps. so amps = watts/volts.
so your 100w bulb is using 8.3 amps.
You'll want something no greater than 45w to get 2 hours out of your battery.

Last edited: Jul 8, 2011
3. ### pbeggsMember

55w/12v=4.58amps
12 amphours/4.58amps = 2.6 hours

4. ### StoltzeeMember

You can buy a 12 volt bicycle light kit, and then use it to charge a little 12 volt SLA battery. Run the front light off the battery, so it doesn't dim when you slow down.

You can get both those items for less than \$40.00
The light is: 12 volt-5.5 watts = .45 AH
The battery is 12 volt .8 AH

Now that battery does come with a motorized bicycle kit with LED's on ebay @ about \$119.00 (I don't like the stupid looking lights with the kit, so I'll make my own).

Last edited: Nov 24, 2012