Amp hour conversion

[michaelrudy89]

Hey guys, I am currently replacing the battery pack as the old setup of 16 8l16 batteries was getting tired at 8 years old now. I found a battery pack that has been refurbished and is rated at 600amps at 8hrs, 570amps at 5hrs and 490amps at 3hrs. I would like to know around what this battery pack would be rated at 20hrs so i can tell my xw6048 charger/inverter what it is.
Thanks!

[Mike90250]

Draw yourself a nomograph

https://en.wikipedia.org/wiki/Nomogram.

[Sunking]

Not sure it matters because it is a used battery, and no used battery will have rated capacity. Depends a bit on the manufacture, but what you are looking for is the Peukert Factor Constant Factor. In this application from 5 to 20 hours discharge rate is going to be on the order of 1.2 to 1.25 so 600 AH's @ 5 Hour Rate x 1.2 = 720ish AH @ 20 Hour Rate. Just call it 700 AH is close enough.

FWIW it is not 600 amps @ 8 hours. That would be 4800 Amp Hours. It is 600 AH @ the 8-hour discharge rate as you would be extemely luck if they even have 500 AH @ 20-hour discharge rate left in them.

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

600 amps @ 8 Hours = 4800 Amp Hours.
4800 AH / 8 Hours = 600 Amps

600 AH / 8 Hours = 75 Amps.
490 AH / 3 Hours = 130 Amps

Huge difference.

[michaelrudy89]

My mistake on writing amps instead of amp hours. I did pretty much the same conversion as you but wanted to make sure i was correct. Its replacing 740ah when new 8 years ago, so i am sure i will be more then happy with it.
The battery pack is 100% remanufactured with a 2 year full replacement warranty.