Battery BackUp, Batteries Explained_AMP HOUR & WATTS

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McGiever
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Location: Junction of PA-OH-WV
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: PEA,NUT,STOVE /ANTHRACITE
Other Heating: Ground Source Heat Pump and some Solar

Post by McGiever » Sun. Apr. 15, 2018 3:31 pm

Borrowed from a Solar Forum so some examples are for large capacity, but the theory and math all bears true...

P=parallel connected & S=series connected and their combinations throughout examples...
Battery Capacity = Voltage x Amp Hours = Watt Hours.

So you have 8 units x 6-volts x 230 AH = 11,040 watt hours of capacity.

There are 4 ways you can configure them, 6, 12, 24, or 48 volts:

8P = 6 volts @ 1840 AH = 11,040 watt hours
2S4P = 12 volts @ 920 AH = 11,040 watt hours
4S2P = 24 volts @ 460 AH = 11,040 watt hours
8S = 48 volts @ 230 AH = 11,040 watt hours

No mater how you configure them, you have 11,040 watt hours. Now for the bad news. Rule 1: You never ever want to configure batteries in parallel unless it is absolutely necessary and if you do will severely shorten cycle life. Thus with 8 of your batteries 48 volts is the way to go. Rule 2 never mix old with new batteries under any circumstances.

Series Batteries Rule: Voltage Adds, AH does not add. So 8 x 6-volt 230 AH batteries in series (8S) is 48 volts @ 230 AH
Parallel Batteries Rule: Amp Hours add, voltage does not add. So 8 x 6-volt 230 AH batteries in parallel (8P) is 6 volts @ 1840 AH.
Watt Hour capacity adds regardless of configuration.

Lastly use as high of a battery voltage as possible as this will say you MONEY and gain efficiency. A good rule of thumb is never exceed 800 AH at any given battery voltage. A 80 Amp Controller has the following panel wattage limitations.

1000 watts @ 12 volts
2000 watts @ 24 volts
4000 watts @ 48 volts


Just remember AH does not mean much of anything without a VOLTAGE. Here some simple formulas.

Watts = Voltage x Current

1200 watts = 12 volts x 100 amps
1200 watts = 24 volts x 50 amps
1200 watts = 48 volts x 25 amps
1200 watts = 120 volts x 10 amps

Amps = Watts / Voltage

100 amps = 1200 watts / 12 volts
50 amps = 1200 watts / 24 volts
25 amps = 1200 watts / 48 volt
10 amps = 1200 watts / 120 volts

Volts = Watts / Amps

12 volts = 1200 watts / 100 Amps
24 volts = 1200 watts / 50 Amps
48 volts = 1200 watts / 25 Amps
120 volts = 1200 watts / 10 Amps

Amp Hours = Amps x Hours
Hours = Amp Hours / Amps
Amps = Amp Hours / Hours

Watt Hours = Watts x Hours
Watts = Watt Hours / Hours
Hours = Watt Hours / Watts
Notice the cost/wh (watthour) for the GC_2 Golf Cart Batteries...

Image

Hope This Helps :)


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