by bartonmd » Fri May 10, 2013 4:05 pm
Yeah, I know it's not linear,(EE, remember) which makes it hard to get FULLY charged, but easy to get 90% charged pretty quickly.
IIRC, don't you have a time delay on your secondary battery setup? Like 5 minutes or something? So if it's 5 minutes, and you drive 25 minutes per trip, you're only charging 40 minutes/day. That's a long shot from the ~6-7 hours of engine-on time that we have on an average wheeling trip. I think part of your issue is that since your battery is back with your frig, not up near the engine, the most it can charge is ~30A or something, so it would need at least 2 full hours of charging to get nearly fully charged. Whereas, if your battery was up by the engine, it could really dump current into it from the alternator, and get it ~80% charged every trip, and it would be fine all the time, though not "fully" charged.
What I normally do with the thermoelectric frig/cooler is, it runs when we're driving, then I unplug it at camp, and it stays cold over night. Plug it back in, in the morning, and it's on most of the day while we're wheeling. Seems to work out pretty well, especially for an $80 frig.
Mike