Is it insane to do 3 charge controllers for one battery bank? (3 x 40 amp mppt)

[Mic the Vegan YT]

Hey guys,

I am sticking hard to a 12V system because I don't have to run cable far and made the mistake of pouring money into a 12V pure sine inverter before learning anything. So my 1,500 watt system is going to need a lot of amperage of charge controllers. Right now my idea is a DIY lifepo4 system with 3 Renogy 40 amp mppt charge controllers. They can do 8 awg and with 3 legs of 5 x 100 watt Rich Solar poly panels at 5 to 6 amps each I would be looking a 25-30 amps for each leg. In other words it would be...

3x: 500 watts of panels at 30 amps max + 40 amp Renogy mppt.

I know you can do 2 charge controllers with this setup but would 3 get too crazy? How does it work with a BMS? Would I need 3 BMS or just on bulkier one? I will be building a 400 ah DIY lifepo4 bank.

Thanks in advance,
Mike

 

[Craig]

You can use 3 or 30 SCC but bms needs to be able to handle combined output. Or use a Chargery style that lets external devices turn battery on or off. Thus way you can feed battery whatever it can handle.

 

[Mic the Vegan YT]

You can use 3 or 30 SCC but bms needs to be able to handle combined output. Or use a Chargery style that lets external devices turn battery on or off. Thus way you can feed battery whatever it can handle.

Thanks. So a 120a DYKB smart BMS would work?

 

[Steve_S]

@Mic the Vegan YT have a look at this response I posted to another member.

How to correctly size SCC?

In Will's book it's number of panels / battery voltage, say 700w / 12v = 58.33 amps but I find some SCC like the 50A Victron says it can handle 700w what am I missing?

diysolarforum.com

Now how much would those renogy SCC's & related hardware add up to ?

 

[Mic the Vegan YT]

Thanks! The Renogy Rovers which can be programmed for DIY Lifepo4 batteries can be purchased for $99 each on Amazon so about $300 there and then the BMS with low temperature cutoff is $60 ish, all with free shipping. So unless I'm forgetting some unique price addition to this setup we are talking $360. A 24 volt system would need a 60 amp controller which would probably be an EpEver Tracer since I need to program it at $240. So for me who has several hundred into a 12V inverter it's worth it. I was thinking about going 2 x 60 amp controllers but the price point goes much higher for programmable ones.