I have a battery pack that is 12V 7.2 amps. I want to run some LED xmas lights from it that are rated at about 7 watts. (100 lights)
How long will these lights run for off this battery pack?How long will I get from my battery pack?You can't really say from the information given. What counts is the number of watt-hours the battery can deliver and the number of watts the lights consume. You have the light consumption, 7 watts. The 12 V battery pack can deliver 7.2 amps but that is not necessarily its amp-hour rating. That might be the maximum rated current in amps. The amp-hour rating of the battery could be more or it could be less.
If we assume that the battery can deliver 12 V times 7.2 amps for 86.4 amp-hours, then you have right about 12 hours of operation. It's not really a bad guess. You could run the lights all night, but would need to recharge the battery every day.
