The OEM start battery on my new van is 70AH, 120RC.
I have a 12v freezer that consumes about 3amps @ 12v. It takes the freezer about 6 hours to freeze a gallon of water.
My battery is not a deep cycle battery. but I wonder about what safe and responsible consumption of that 120 minute @25a reserve really is? In theory that means I have about 50AH available before my battery is done.. but I need my battery to start and I also would like to have my battery last 3+ years at least.
anyways... freezer 3amp for 6 hours is about 18AH.
Question 1. Safe to run the freezer for 6 hours and expect to start and not hurt my battery too much?
Question 2. I ran the freezer for an hour and my battery dropped from 12.7v to 12.3v.. but then I ran my engine for 5 minutes and my battery read 12.7v again. My alternator is 160a (2.4L gas 4cylinder engine). Possible my alternator recovered that hour so quickly? If so wonder about the strategy of just checking in on my battery with some 15 minute engine runs a few times during the 6 hours? Note the freezer has a low battery 11v disconnect feature.
Question 3. Wondering about dual purpose batteries rated at 110AH, 205RC with plenty of cranking amps (like 900CCA)… if this fits, any reason not to upgrade to that next time? I've heard of others doing this.
UPDATE PLEASE SEE COMMENTS BELOW ON SURFACE VOLTAGE AND ADDITIONAL TESTING WE DID.