Hi Scrub,
The real answer is "it depends".
I serviced 875 amp-hours of 12 volt batteries with 256 watts of solar. To do so I used two banks with switching. I got 6 years of life from one set of three and 10 years from one set of four.
For a part time rv'er, so long as there is 60 watts of solar per 100 amp-hours the battery bank can be equalized. There is not much point from a battery charging point of view in having more than 150 watts per 100 amp-hours as the charge acceptance rate for flooded lead acid batteries at 85% state of charge is about 12.5 amps (i.e. 150 watts).
What IS important is adjustable voltage set points.
For a full timer an energy audit will be a necessary process to find the wattage needed.
scrubjaysnest wrote:
Your 400 watts of solar is a perfect match to 2 105's in full sun. But for, four most likely you won't get the max life out of the batteries. To balance the two battery banks your wiring will need to be large and carefully done.
Per Trojan c/10 or 22.5 amps per bank is preferred. A bank is 2 6 volt batteries in series.
