Originally Posted by Dave Lochner
State of Charge generally refers to the amount of battery
capacity that is available to use. If we start with a battery
with 100 amp hour capacity and draw 10 amps for 5 hours, we now have a battery with 50 amp hours available or a 50% SOC.
Not quite, you are forgetting Peukert. When a battery is rated at 100 AH it is based on the 20 hour rate. For a 100 AH battery that means a 5 amp draw over the 20 hour period.
If you draw 10 amps from the same battery you will have a lot less than 100 AH available. The reverse is also true - if you draw 2 amps from the battery it will have a larger capacity than 100 AH.