# What is the Correct Way to Add Battery Amp Hours?

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Registered Users Posts: 4
I have 12 -12V batteries installed on my Grid Tied Battery Back-up System. 2 - Sunny Island 5048-US, Split phase 240V, 10K, Gird Tied, No generator, 36 - REC 235PE Solar Panels & Sunny Boy 8000-US inverter.

The batteries Specs: MK Battery, Model # 8G8DLTP-DEKA, Nominal Voltage = 12V, Capacity at C/100 = 265Ah, Capacity at C/20 = 225Ah, Plate Alloy = Lead Calcium.

My batteries are wired for 48V, 3 sets of 4 batteries in series/parallel.

If the batteries were connected in Parallel, for only 12V, then I think one would just multiply 12 x 265 = 3180 Ah, Right? So then how does one figure total amp hours for a 48V system?

What is the Correct Way to Add Battery Amp Hours for my system?

Sorry for the newb questions.......Please teach me........

• Solar Expert Posts: 3,741 ✭✭✭✭
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Re: What is the Correct Way to Add Battery Amp Hours?

Four 12 volt 225 AH batteries in series is 48 volts and 225 AH
Three strings of the above in parallel makes 48 volts at 675 AH

--vtMaps
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
• Registered Users Posts: 16 ✭✭
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Re: What is the Correct Way to Add Battery Amp Hours?

3 x 265 @ C/100
3 x 225 @ C/20

Theortically, you only have three batteries in parallel, regardless of the final voltage Sum you have.
• Solar Expert Posts: 1,571 ✭✭
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Re: What is the Correct Way to Add Battery Amp Hours?

And remember that when you program the capacity of the batteries into the sunny island, it's expecting the C10 rate.
• Registered Users Posts: 4
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Re: What is the Correct Way to Add Battery Amp Hours?

Thank you for responding to my request!
This info will help me get it right......
• Solar Expert Posts: 1,571 ✭✭
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Re: What is the Correct Way to Add Battery Amp Hours?
stephendv wrote: »
And remember that when you program the capacity of the batteries into the sunny island, it's expecting the C10 rate.

DGM17, apologies the US version of the SI requires the C20 rate. I have the EU version which requires C10... no idea why they would change something like that between regions.