# Battery Question...

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Solar Expert Posts: 84 ✭✭✭✭
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

• Banned Posts: 17,615 ✭✭✭
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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.)
• Solar Expert Posts: 84 ✭✭✭✭
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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.)

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