Like I said, if you use your car battery, monitor the voltage and be sure you start it up before it gets too low. The guys with the larger LiPos leave their engines running quite a bit, if not all the time.

540 cranking amps is NOT a capacity measurement. It is a measure of max current output for a short period of time.


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You completely missed the point Iwas trying to make. If he charges the pack 1 time, sure that would only be a 15-20 amp loss, not enough to hurt anyhing. BUT, repeated charging at the field will bring the battery down MUCHmore than that, then you will need to rely on the alternator to RECHARGE the battery, NOTAGOODIDEA!!!! Why do you think the others 'leave their cars running quite a bit, if not all the time'?????????? The alternator can certainly handle a constatnt 15-20 amp draw if the car is RUNNING, but not a good idea to use the alternator as a recharging tool.Leaving the car engine running will most certainly use more gas than the 1 gallon in 5 1/2 hours that my generator uses.
The amperageratingis the capacity of the battery, much the same as the mah rating on your batteries. Car battery manufacturers don't print the total amperage capacity on the batteries except in a 'cranking amps and cold cranking amps' rating, but the end result is the same. To tell you the capacity of the battery.
Also, a 12 volt car battery is actually 12.6 volts base battery voltage. The actual voltage while the engine is running is more like 14.2 volts, so the calculated draw will be different. 15 amps draw @ 12.6 v, more like 13 amps draw @ 14.2 volts. Better to charge with the engine running, except for the large ammount of fuel that you will use.
Any way you look at it, a small generator is still the best way to go.