View Full Version : battery wizard needed
what is the smallest and lightest li-po battery that would be needed to have a 12V 10W HID bulb burn for 4 hours?
frankg11
12-06-2005, 04:19 PM
What you setting up a night light for a bike? If so which model bike light?
if you already have a ni-cad pack figure out the voltage and amps. Just cycle the battery in your charger.
I have a NightRider HID that has Ni-Cads. Runs about 4 hours. I haven't torn the pack apart but I believe it's a 2s2p pack with six "C" cells. which makes it what about 7.5 volts. I will try to test the voltage tonight if I remember.
So just hook up a watts-up to the existing pack measure voltage and figure out the needed capacity.
BTW - I considered the same thing for a bit, still might but haven't worked out all the details. This is my plan for figuring out the capacity and voltage.
flyinfool
12-06-2005, 08:38 PM
With LiPo you can run 11.1v or 14.8v with a 12v regulator.
12v at 10 W for 4 hours would be 3333 mAh with no reserve and in a perfect world.
flyinfool, that's what I was looking for, so to get 11.1v that would be 3X3.7v packs.
now what is the highest mah?, all I can find are 2250mah packs.
am I right to say that if the only battery I can find is a 3.7v @ 2250mah that I would need 6 of them to make it 11.1v @4500mah?
playfair
12-07-2005, 10:28 AM
10W/12v=.83a x 4hrs= 3.33ah
Check to see if the HID ballast will operate down to 10v, and how much current it pulls at that level.
From Thunder Power (other brands may also apply):
TP4000-3S2P 4000 mAh, 11.1V (charge as 3 cells), 13G wire, 4-pin balancer connector
Rating: 12C(48A) continuous, 20C(80A) burst
Dimension: 50mm x 185mm x 17mm Weight: 255gm
$149.95
Theres also a 4200 pack (safety factor) for $15 more.