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12v ah to 48v ah?

Kingpyron

New Member
Joined
Jul 20, 2022
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Just wanted to know if I bought 4 12v 300ah batteries lfp and wired them in series and parallel will this provide 48v with 1200ah? If not do I need more batteries to compensate? I'm ultimately trying to have a battery bank with 30kwh give or take.
 
Think of this in watt hours, those translate across volts and amp hours.

12v 300ah = 12 x 300 = 3,600wh

But 30 kwh is 30,000 watt hours. Just about 10 times more. Sure that's the number you need?

Doesn't matter if you have those as 12v parallel or wired up with groups of 4 in series to make 48v.

At 12v you'd need 2,500ah (30000/12=2500). So that would be something like 25 100ah 12v batteries.

At 48v you'd need 625ah. So that would be approximately 6 of the 48v server rack 48v batteries (which are ~100ah at 48v or ~5khw each).

One way of thinking about the costs is to think in terms of $ per wh. e.g., check Will's page at https://www.mobile-solarpower.com/lithium-batteries.html. That shows 48v server rack batteries at ~$0.30 per wh, so that would be ~$9,000. Could be done cheaper with diy cells.
 
You need to know the classic electrical saying, in series volts add while amperage stays the same, whereas in parallel amps add while voltage stay the same.

So, by putting four 300Ah,12V batteries in series, you get 300Ah at 48V. That works out to be 300Ah X 48V = 14,400Wh

If instead, you wired those four 300Ah,12V batteries in parallel, you'd get 1200Ah at 12V. That works out to be 1200Ah X 12V = 14,400Wh.

So, to answer your question, you'd need 2 parallel strings of four batteries each (that 4S2P) to give you ~29kWh of power.
 
You need to know the classic electrical saying, in series volts add while amperage stays the same, whereas in parallel amps add while voltage stay the same.

So, by putting four 300Ah,12V batteries in series, you get 300Ah at 48V. That works out to be 300Ah X 48V = 14,400Wh

If instead, you wired those four 300Ah,12V batteries in parallel, you'd get 1200Ah at 12V. That works out to be 1200Ah X 12V = 14,400Wh.

So, to answer your question, you'd need 2 parallel strings of four batteries each (that 4S2P) to give you ~29kWh of power.
Yeah, I missed that the OP was talking about 4 separate 300ah 12v batteries :)
 
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