Reverse SOC Meter

George BetakSF BayLEAFs

2

Overview

DTE (distance to empty) not accurate enough

Lovingly called Guess-O-Meter (GOM)

Individual range prediction techniques

Supplemented by SOC meter (Gary Giddings)

3

Range Chart by Tony Williams

Pioneering work by fellow owner in San Diego

Proven that there is life without DTE

Established key metrics for battery warnings, turtle, etc.

Relies on energy economy numbers and trip mileage

4

Gary’s SOC Meter

Uses EV-CAN bus message 0x5BC

Additional device installed in the car

Individual units are called “Gids”

Mapping of Gids to battery bars and range

Accurate prediction of battery events: LBW, VLBW, turtle

5

Charging Time Display

It works!

Already in the car

Relatively easy to comprehend

Linear mapping to Gids

Can predict battery events

6

Range Prediction – Long Answer

7

Range Prediction – Short Answer

Divide trip miles by number of hours to charge

1 hr to charge on 120V is:

• Approx. 0.8 kWh• 11 Gids• 3 miles @ 4 miles/kWh• Measure trips in hours

8

Future Work

Simplify instructions for L1 opportunity chargers

Validate against large data sample

CAN bus logging using Gary’s meter

Improve mapping to battery bars