View Single Post
Old April 28th, 2010, 21:33   #3
kalnaren's Avatar
Join Date: Dec 2006
Location: Oakville, Ontario
For Ni-Mah batteries:

Take the battery Mah rating, divide by charger Mah rating, multiply result by 1.15.

For Ni-Cad, multiply the result by 1.2.


1800 mah battery, charger rated at 300 Mah. 1800/300 = 6, 6*1.15 = 6.9 hours, or 6 hours and 54 minutes.

You do the multiplacation because batteries are not 100% effeciant. Ni-Cads only retain about 80% of the power put into them, Ni-Mah a little more.

"Someone in a Prius tried to race me at a stop sign the other day. I couldn't believe it. I had him for the first 100 feet or so but I can only walk so fast."
kalnaren is offline   Reply With Quote