[Ovmsdev] Mileage and consumption

Tom Saxton tom at idleloop.com
Sun May 13 08:21:43 HKT 2012

on 5/7/12 4:02 PM, Rens Meijer wrote:

> Overnight I charged the car in standard mode and the next morning it showed on
> my kWh meter in my charging equipement and on the VDS that it used 52 kWh (so
> it seems to be quite accurate), but I only consumed 41 kWh during driving. My
> feeling is this is quite high, but I have not much data to compare this.

Hi Rens,

I've been tracking this sort of thing since we got our Roadster in June of

The car's estimate of the energy used to charge was quite a bit lower than
what the wall meter reported in early versions of the firmware, but got much
better with a firmware upgrade fairly early on.

Comparing what the VDS trip meter says for energy used with charge energy as
read from the dedicated utility meter feeding out HPC, I find efficiency
values from 57.5% to 90.1%, with an average of 75.4% and median of 74.5%.

Of course, we don't really know what the trip meter energy reading is
telling us. Does it include energy used for HVAC? I'm pretty sure it doesn't
include energy used when the car isn't on. So, that number is probably not
really charging efficiency.

I've been logging this information manually, with occasionally some help
from the log file. It would definitely be handy for OVMS to help log as much
of this information as possible for us.


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