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Old 11-13-2008, 07:15 AM   #1
Join Date: Sep 2008
Location: Oregon
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Battery Power Questions

Would like to know how many batteries y'all are using and your real world Amp/Hours performance? I'm trying to figure how much out how much stuff I can run in a typical day before the batteries die. Target vehicle is a modified RB-50. Also, how much drain is too much and how long do batts take to recharge?


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Old 11-13-2008, 09:05 AM   #2
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There are so many variables that it is hard to answer. You must also take into consideration where you will be camping as temperature is a large factor. There have been lots of discussion lately on batteries and if you look through some of the previous posts here and also in the electrical section I think you will find some good discussion to help you. oclv

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Old 11-13-2008, 09:33 AM   #3
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I have 4 batteries on my rig. Two to start up the 7.3 diesel engine and two to run all the stuff in the back (frige, ipod charger and whatever). The two batteries for the back are hooked up to a 135 watt solar panel. But I was wondering the same thing...How low can these batteries get before I need to hit them with some charge from the engine. I haven't used them too much so far. The lowest I have seen them is around 12.1 watts...
2000 E-350, 7.3 Power Stroke Diesel. 4x4. Loaded. "The Big Gray Whale"
1982 Mercedes 300D. WVO, SVO and Biodiesel for the last 30,000 + miles. (my 600 mile a week commuter).
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Old 11-14-2008, 03:02 PM   #4
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We have 2 house batteries and a 125W solar panel. Our only loads are the 12V refrig, some lights, the water pump and sometimes the furnace. Unless we are in full shade we can get enough solar charge to keep going forever.

12.1V is a normal level for overnight. Anything over 11.0 is enough to keep me happy.

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Old 11-14-2008, 04:29 PM   #5
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I have two 4D AGMs and in theory they are supposed to give me 3 days of parked fridge, light, and toaster time. In reality with the propane heater running (fan draws electrical) and the fridge I was starting my van every day- even without the toaster. However that includes real world mistakes like leaving the invertor or lights on all day on different days, and I think my batteries might be toast.
and then
everything changed
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Old 11-14-2008, 10:24 PM   #6
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No-load voltage alone can be an indicator of remaining per cent of full charge, but with a considerable margin of error depending on such variables as battery age, condition, number of charge cycles already experienced, temperature, etc. In general, from what I've read in various places, a no-load voltage of 12 volts on a healthy AGM house battery indicates that it's near the 50 per cent discharged point, and lots of AGM makers and sellers suggest not going below that point on a regular basis. If I find we've dipped below 12 volts and we're parked for the night, I either turn everything off except the fridge, or run the generator for 20 minutes or so. As near as I can tell from my reading, discharging an AGM battery to below the 50 per cent level now and then may be okay, but doing it repeatedly will shorten the number of charge cycles the battery can handle - i.e., in my simple layman's terms, my battery will die sooner.

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