# Electrical Equation

• 07-05-2005, 12:03 PM
KyleYankan
Electrical Equation
Hey everyone. I thought we'd all throw in some electrical/computer/audio equations here and throw it into the FAQ.

Ohm's Law:
Ohms = Volts / Amps
Amps = Volts / Ohms
Volts = Ohms * Amps

Watts Law (?)
Watts = Volts * Amps
Volts = Watts / Amps
Amps = Watts / Volts

Can anyone throw the battery time thing up? liek fi your system draws 3 amps, it takes 5 hours to kill battery? thanks.
• 07-05-2005, 12:05 PM
god_of_cpu
From here: http://www.1st-optima-batteries.com/amp_hours.asp

Two standard ratings are used to measure a battery's storage capacity.

Amp Hours

The Amp Hour rating tells you how much amperage is available when discharged evenly over a 20 hour period. The amp hour rating is cumulative, so in order to know how many constant amps the battery will output for 20 hours, you have to divide the amp hour rating by 20. Example: If a battery has an amp hour rating of 75, dividing by 20 = 3.75. Such a battery can carry a 3.75 amp load for 20 hours before dropping to 10.5 volts. (10.5 volts is the fully discharged level, at which point the battery needs to be recharged.) A battery with an amp hour rating of 55 will carry a 2.75 amp load for 20 hours before dropping to 10.5 volts.

Reserve Minutes

Reserve minutes is the number of minutes a battery will carry a 25 amp load before dropping to 10.5 volts. (10.5 volts is the fully discharged level, at which point the battery needs to be recharged.)