24 volt to 12 volt converter

tdevery wrote:
Looking to run 600 watts of solar to my 40 amp MTTP controller at 36 volts.
I have 4-6 volt batteries.
So I need to get my 24 volt battery bank down to 12 volts to my Magnum 2012 inverter charger.
Any recommendations on which unit.

600 watts in my book is right on the limit of 12 volt systems.
now, your 40 A controller is too small for a 12 V system unless you intend to throw those watts away.. 40A*12V=480W and you waste 120W ! not an ideal situation.
also, for a 12V system you will need a 12 V battery bank of at least 320 Ah, preferably 400 Ah to match your CC output.
if you go to 24V then 600/24=25Amps .. no problem for that controller and your battery Ah minimum is 200Ah preferably 250Ah
also your panels will be wired in series so 36*2=72 Voc and allowing 1.2x times for cold startup gives 86 Voc max so your good there.
not knowing your batteries, I would guess they are golfcart 6V
and nominal 225Ah.. thats a reasonable match for 24V operation.

I suggest two options here.

1. ditch the 12V inverter and go to a 24V model inverter/charger
and purchase a 24V to 12V buck converter to power the RV, forget the TV 12v, you dont need it
2. stay with 12V, ditch the 40A CC and purchase a Victron blue 100/50 and sigh... connect those batteries as a 2p2s string CORRECTLY. now you have 450Ah and a workable system.
just cable it correctly with the right AWG.