Steve and list,
> Of course, you wouldn't start the car with the lights
>on, but 20 amps times 12 volts is 240 watts into the lights. I've got to
believe
>that figuring the resistance of the battery into that equation would show a
heat
>dissipation in the battery. The only issue would be 'is it sufficient to
overcome
>the drain and make a difference?'.
If you take the simplistic position that a battery manufacturer touts 850
cold cranking Amps, that would say that the internal dc impedance would be
somewhere around 12V/850A=0.014 Ohms. (totally discounting the dynamics of
high current discharges) The power dissipated into this internal battery
resistance during headlight "warm-up" would be 20*20*0.014=5.6Watts. That's
not exactly a heat wave generator. If the lights were left on for several
days, it "might" raise the temperature of the 25 lbs. of lead and acid by a
few degrees. I wouldn't count on it having enough energy left to start
anything though.
Cullen Bennett
Tempe, Arizona USA
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