24 volt to 12 volt converter
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. ...
Forum Discussion
brulaz wrote:
OK, after more googling I'm pretty sure that the effective internal resistance of batteries in parallel should drop according to OHM'S law:
1/(1/r1 + 1/r2 ...)
So V drop of 4 GC2s in 12V configuration should be half that of 4 GC2s in series in 24V configuration.
So guess my observation of fixed V drop under 12V or 24V was a fluke. Perhaps the batteries were at a different SOC, the Inverters were different, who knows ... it wasn't exactly a controlled experiment.
Adding more batteries to the bank reduces the R of the bank for the same voltage system (12v system eg) That is how you can now run higher amps with the same voltage sag (or have less voltage sag for the same amps) by adding batteries to the bank. Bigger inverter draw needs more battery bank to stay above its alarm voltage.
I can't figure out what happens to R when you change the voltage system using the same battery bank (if that is what we are doing here)
All I can see is that 24v inverter has its alarm at 22v and my 12v inverter has its alarm at 11v. That must mean something!
