Part of his solar needs are to improve battery life I thought?
That is about 90% correct. The other 10% is to augment alternator charge when the truck is parked in the desert with the fridge running. In hot weather, I can usually only get about 24 hrs of fridge run time on my pair of G34 Optima house batteries on a full charge, so if I can get a solar controller that will work during the heat of the day, that mitigates the need to drive the truck to recharge those batteries. A pair of Northstar 34s will give me about 20 ah more than the Optimas, and a pair of Odysseys will give me about 26 ah more than the Optimas. Just learned today that Northstar has lower resistance than Odyssey and Northstars are fine on 14.4-14.6 absorption charge, while Odysseys need 14.7. So Northstars should be OK with the controllers like the GoPower that are preset at 14.4V. The Victron PWM-Duo is programmable at 14.6 and 14.8, but comes from the factory at 14.4. There are Victron Duo controllers in stock at the Maine warehouse, but all the Victron Duo monitors are still in Europe, apparently only available here on special order. The Victron battery that I wanted as my starting battery is not being imported into the US, and the Victron house batteries are somewhere in the Atlantic headed for Maine. Can't wait for those, so maybe just going with three Northstars. Have not been able to find any AGM or lithium true deep cycles with decent capacity that will fit my available space for the house batteries.
Back to the 90% correct part. That 90% of the solar is intended to keep all three batteries topped off when the truck is parked for prolonged periods between trips and the fridge is not running. The alternator will bulk charge everything but the solar should take care of the long-tail absorption charge and parasitic drain, and a two-bank controller should provide whatever the two banks need, independently of each other when isolated. The GoPower will work up to 185F ambient, while the Victron is good up to 131F. I'm still at home and it's 113F today.
Can't use FLA for the house batteries because space constraints require that they be mounted on their sides. Gel is out because of sensitivity to charging profiles. Can't find lithiums that are a good fit for the house battery boxes. So back to AGM, and Northstar has the advantage over Odyssey because of the resistance issue. Could go with Dekas as a cheaper alternative, but changing batteries is such a hassle that I'd rather spend more and change them less frequently. FullRiver advises against using their Full Throttle dual purpose AGMs in my application.
