24v PV 12v Lifepo4 3.6kwh Batteries

[Jake]

Have a new RV being built. Could have ordered it with Flex PV’s but didn’t think they would last long in Texas Sun! While designing (selecting components) I came up with a Thought? Could I hook up my PV’s in a parallel/series to 24v input to a MPPT charge controller formatted for 12v batteries? For sure Wire Size would be smaller, controller wouldn't have to be a 40/50 A (more like 20/30 A) and $$$ would go down.
Does anyone think of a reason this wouldn’t work?

 

[svetz]

Hey Jake! Welcome to the forums!

For Sure! W = V x A, so doubling the V at constant watts halves the current.
Cost and safety are big topics. You might like these threads as they touch on the ideas you're talking about:

• What does it mean to have solar panels in parallel and series?
• Figuring out how many panels in series and parallel based on your MPPT
• What wire gauge should I use?

 

[Jake]

Thanks SVETZ!
I knew there was someone out there that believes the same as me! One of your Threads was something I was worried about... Shadows! Never thought about the bypass Diodes! (As well as the Isolation Diodes).
The new RV comes with 2 6v 280ah AGM batteries as House Batteries. Didn’t really want to throw them away (until they die). So I will put 2 diodes in the charging to isolate the two types Of batteries. The Lifepo4’s will run the 2Kw inverter and the AGM the lights (LED), refrigerator controller, fans and CPAP? The MPPT comes with a low temp sensor to stop the charging if close to freezing, but I’m still a little concerned about high temperatures on the Lithium here in Texas...
Again Thanks! ?

 

[svetz]

Hey Jake, not sure about your specific configuration... most panels usually come with diodes these days (check though, heard some disturbing things). Also AGMs and Lithiums don't play well in the same sandbox. There's a couple of threads on it, but you'd be better off not mixing the two. High temperature can be bad for Lithium, there's talk about that if a few places too and what folks are trying to beat the heat.