Two charge controllers with renogy dc to dc charger with mppt

[Lez_go]

Planning my 12v system for my van. It's an old red cross ERV.

I have 412 AH of SOK lithium batteries already but haven't purchased anything else.

I am planning on a rather large solar array, as my vehicle is huge (112 square feet) and I would like to maximize the space with panels on the roof. But I'd also like to incorporate dc to dc charging.

I am wondering, since the renogy dc to dc charger with mppt has a max pv input of 25v, could I theoretically design a system with 4 100w panels in parallel running to the dc to dc charger with mppt, AND add another MPPT charge controller with an additional 600 watts (probably rich solar 200w panels in series)?

Is there anything I would need to be worried about with these two systems working together, other than wire size and fuses?

 

[Lez_go]

Does it have to do with the batteries themselves? SOK states that each 206ah battery has a max input of 50a. I'm planning on running two in parallel.

 

[fratermus]

since the renogy dc to dc charger with mppt has a max pv input of 25v, could I theoretically design a system with 4 100w panels in parallel running to the dc to dc charger with mppt, AND add another MPPT charge controller with an additional 600 watts (probably rich solar 200w panels in series)

Sorry for the slow response; just saw this.

Multiple charging inputs are fine. You could run every panel on a separate controller if you wanted. Sometimes folks on sailing yachts do this because of the complex shade patterns from sails and other equipment. In this scenario most people would config the setpoints to be the same. The only gotcha I can think of is if one of the controllers is using trailing amps to terminate Absorption then it could get confused and drop to float early.

I assume you have already bought the gear, but if you haven't a standalone DC-DC charger + 1000w of matched panels + one big (80A maybe?) mppt might be cheaper. Especially if you find used 24v panels like the $50 250w 24v Will had a video on.

I don't think the setup could exceed 100A charging (2x SOK in parallel) but 50A might be healthier for them.