Battery Question...

paulskirocks

OK, I'm down to needing batteries... I will have 920 watts of panels, 2 strings, into a Morningstar MPPT 45 Amp controller, into a 24 volt battery bank... Looking at the numbers of the panels, each string will be close to 8 amps, so 16 amps max into the controller... Will this be enough to keep 200 amp hours worth of batteries fully charged and happy? It's my understanding that 20 amps would be more ideal, so I wonder if I should downsize my amp hours... Thanks

Cariboocoot

Re: Battery Question...

MPPT controller, so the current to the controller doesn't matter; it's what it can put out that does.
The formula looks something like this: 920 Watt array * 0.77 efficiency / 24 Volts = 29 Amps peak charge current potential.
That should have no trouble keeping, say, a string of 220 Amp hour 6 Volt golf cart batteries happy. Or even a string of 232 Amp hour 6 Volt East Penns. (That's what I have on my mere 700 Watt array; no problem.)

paulskirocks

Re: Battery Question...

Cariboocoot wrote: »

MPPT controller, so the current to the controller doesn't matter; it's what it can put out that does.
The formula looks something like this: 920 Watt array * 0.77 efficiency / 24 Volts = 29 Amps peak charge current potential.
That should have no trouble keeping, say, a string of 220 Amp hour 6 Volt golf cart batteries happy. Or even a string of 232 Amp hour 6 Volt East Penns. (That's what I have on my mere 700 Watt array; no problem.)

Ahhh, OK, I was wondering about that... I need to think watts, not current... MPPT is pretty neat technology... Thanks for the quick reply...

BB.

Re: Battery Question...

And the Vmp-array needs to be >~35 volts to properly recharge your battery bank. It sounds like your Vmp-array should be around 57 volts--Which is fine.

-Bill

paulskirocks

Re: Battery Question...

Yea, each panel is 29.4 vmp...