I would like to discuss Eaton PWHR12390W4FR battery (datasheet link here).
These batteries are specified through Constant Power Discharge Characteristic (see first table in datasheet), as opposed to constant current usual for other batteries, and are designed for high loads. It is impossible to find their C20, so I calculated it. Datasheet uses 1.67 Volt per cell as end voltage for specified 390W, so I used 1.67Vpc data line to calculate Peukert constant. It varies depending on what points are used. I also used approximation from power to current by dividing power by middle point between 2V and 1.67V => 1.835V. So in the image below, the 133.5A is 245Watts/cell from 1.67V row and 30min column divided by 1.835V.
My calculation says this is approx C20=130Ah battery.
Yes, it says 131.8Ah in my image below, but that number is massaged and even Peukert varies depending which two points are used to calculate it, so lets not worry about 3 digit precision.
NOTE: These have only 3mOhm internal resistance, which is much lower than for example comparable Crown 31HDC130 8.7mOhm and on par with much larger PowerSafe SBS190F 3.2mOhm. So theoretically, if they are designed for fast discharge, they should also charge fast.
I know nothing about PWHR12390W4FR other than what's online, but someone in my area is selling largish amounts of used ones for C$100 (approx $73 => $46/kWh). I have the battery tester that is able to estimate remaining capacity (and its been decently close so far) so I can pick good ones. Somewhat low cycle life 260 @ 100% DOD is not as relevant because my application is seasonal off-grid property, so they will not be daily drivers and most of the time will be sitting idle.
These batteries are specified through Constant Power Discharge Characteristic (see first table in datasheet), as opposed to constant current usual for other batteries, and are designed for high loads. It is impossible to find their C20, so I calculated it. Datasheet uses 1.67 Volt per cell as end voltage for specified 390W, so I used 1.67Vpc data line to calculate Peukert constant. It varies depending on what points are used. I also used approximation from power to current by dividing power by middle point between 2V and 1.67V => 1.835V. So in the image below, the 133.5A is 245Watts/cell from 1.67V row and 30min column divided by 1.835V.
My calculation says this is approx C20=130Ah battery.
Yes, it says 131.8Ah in my image below, but that number is massaged and even Peukert varies depending which two points are used to calculate it, so lets not worry about 3 digit precision.
NOTE: These have only 3mOhm internal resistance, which is much lower than for example comparable Crown 31HDC130 8.7mOhm and on par with much larger PowerSafe SBS190F 3.2mOhm. So theoretically, if they are designed for fast discharge, they should also charge fast.
I know nothing about PWHR12390W4FR other than what's online, but someone in my area is selling largish amounts of used ones for C$100 (approx $73 => $46/kWh). I have the battery tester that is able to estimate remaining capacity (and its been decently close so far) so I can pick good ones. Somewhat low cycle life 260 @ 100% DOD is not as relevant because my application is seasonal off-grid property, so they will not be daily drivers and most of the time will be sitting idle.
Last edited:
