Ingineer
Well-known member
It was recently asked how I derive SOC for LEAFSCAN. This number is simply obtained from the Battery ECU, and is displayed as-is. The various Leaf systems use this as a basis for making operational decisions and displaying information. The SOC is created by coulomb counting, which is basically defined as counting the electrons passing in/out of the battery. Due to the fact that it's not actually possible to do this very accurately in a mass-produced EV, the battery ECU periodically makes adjustments to keep the SOC as accurate as possible. One of the main ways this is done is by checking open-circuit voltage of the pack and applying some math to correct this number for things that will affect it, and using a lookup table of known states. This all working together makes for a pretty accurate SOC calculation. The Leaf's engineering team make use of a hall-effect based current monitor to perform the coulomb counting, and these have a number of issues that make them less accurate than ideal, but they are cheap and good enough.
The reported SOC usable range seems to be from about 95% (fully charged) to 2% when the battery main contactor opens up and disconnects the pack. The first low battery warning occurs at around 18%, and the second one at around 9%. If I remember correctly, Turtle mode comes on at about 5%, and begins limiting power. At about 2%, you are totally dead.
-Phil
The reported SOC usable range seems to be from about 95% (fully charged) to 2% when the battery main contactor opens up and disconnects the pack. The first low battery warning occurs at around 18%, and the second one at around 9%. If I remember correctly, Turtle mode comes on at about 5%, and begins limiting power. At about 2%, you are totally dead.
-Phil