I have two batteries that are isolated and my intention is to charge the primary then the secondary using a MPPT charger. I’m finding out that this is not as straightforward as I thought. There’s MPPT chargers out there that can do this but not victron. I’m for the most part decided on using victron products as I feel they provide a quality product and their software is well supported.
One of my dilemmas is that my secondary battery will have twice the capacity of the primary. With that said, charging the primary battery is priority #1. I feel charging them in parallel would hold back the primary as the secondary would soak up amperage.
My second option is to charge one battery via the MPPT and the other via a DC to DC charger. I’ve been reading the manual for the solar smart chargers but one thing I’m not quite understanding is the limitations of the load output. Messing around in the app I can see that you can set certain criteria before the controller enables power to the load circuit. My question is, does the solar charger have the limitation of either charging the battery or supplying power to the load, or can it keep a float charge on the battery while supplying excess energy to the load circuit, which in this situation would be a DC - DC charger that’ll charge a secondary battery.
Alternatively, and this is a third option that I’ve seen get recommended on here, is to charge one battery using a DC-DC charger powered by the second battery, and to keep the second one charged up using the MPPT. I’m not a huge fan of this option personally.
In my opinion option 2 is probably the best option, if it can be made to work.