Capacity Test on 48v Battery without Inverter

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Zebretta
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Capacity Test on 48v Battery without Inverter

I have a 48v 20Ah battery (LiFePO4) that I need to test the capacity at at least 20Amps.

It’s no problem with my 12v 100Ah battery because I can use my dummy load tester at 10Amps for that Watts = 12v x 10amps = 120watts
But with the 48v battery watts = 48v x 2.5Amps = 120watts.

I don’t have anything in my toolbox that can do that. Not at 20 amps.

I do have a few of those 150amp battery monitors and a few others with shunts, but nothing specifically for a 48v battery.

What’s the easiest way to do this given the above? Resistors? Shunt?

Thanks

Robin Dobbie
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No way to unbolt the cells to test individually?

I just got a 40A tester, but its limited to 400W. So that wouldn’t help even if you were close.

Zebretta
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Robin Dobbie wrote:
No way to unbolt the cells to test individually?

I just got a 40A tester, but its limited to 400W. So that wouldn’t help even if you were close.

Thanks just the same Thumbs Up

It’s just current at 48v so it’s mostly just math and picking the right resistors.

I’ll figure it out or ask at an electronics forum.

chops728
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You might have better luck asking on this Forum

https://diysolarforum.com/

kennybobby
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Go to the thrift store and buy some used stove eyes. Four of them wired up in parallel should get you down to the 2.4 Ohm range.

eyes

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

Zebretta
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kennybobby wrote:
Go to the thrift store and buy some used stove eyes. Four of them wired up in parallel should get you down to the 2.4 Ohm range.

eyes

Hey, hadn’t thought of those. That might be a workable idea

Thanks