EV miles from OBD2?

Hexperience said:

I'm thinking about picking up one of those OBD2 readers but wanted to know if I can get the total EV miles from that? I really can't understand why they don't show more details on the information screens in the Volt. I do understand that not everyone cares about the extra details but lots of people seem to be buying those OBD2 readers so why not just have a detailed stats page?

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Based on my experience with an OBD2 reader and the Android apps MyGreenVolt and Torque Pro and my 2012 Volt, the answer is no, you can’t just plug in a dongle and see a readout of your total mileage and ev mileage like you can using the OnStar and MyChevrolet apps or view on the MyVolt or MyChevrolet or VoltStats.net (if your Volt is registered there) websites. An OnStar Basic account or greater is needed to view your data on those sites.

My understanding is that the MGV and TP apps can track and record daily ev distances driven if the dongle is plugged and the apps are receiving data as you drive (n.b., I use my OBD2 reader only occasionally). Daily ev distances, when added to the number of ev miles at the time you started to use the apps, produce lifetime ev distance. This number should reflect the same number obtainable from OnStar data on their apps or on the websites.

MyGreenVolt provides a configuration data file that can be edited to adjust for your current ev miles when you install the app. Bro1999 indicates that Torque Pro data can also be logged to track daily ev miles, which can then be used to obtain the lifetime ev miles.

These two apps do, however, provide a wide range of data on the Volt’s operation (such as cell voltage and battery SOC%) that are not available on the websites or on the car’s displays.

Hexperience said:

Thanks for that. I still may get one for the cell voltage and other interesting stats.

So if the lifetime EV stats are not recorded in the car, I wonder if OnStar will ever be able to recover true lifetime EV miles. It sounds like they were just keeping a running total from each update.

It's not really that big a problem in the grand scheme of things but it does taint what is otherwise a really great car.

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I would think each vehicle maintains data in its own computer that is not available via the OBD port under the steering wheel. The calculation for "Lifetime MPG," for example, requires knowing the "lifetime Gas Used" total. Such lifetime data is likely maintained on the car’s computer, which could then be programmed to upload this or that information via the OnStar connection to those with access to the program.

The full-charge, start-of-day ev and gas range estimates also are based on long-term data collection within the vehicle. Once the car is unplugged and heads off, changes in terrain, environment, and driver’s driving habits may modify the range estimates. The computer gathers data "on the fly" to update the range estimate as you drive. These estimates appear on the driver’s display. I’m not sure if such information (start of day/on the fly range estimates) would be available via the OBD port.

Choosing to display any data on the dashboard, however, is not something to be done lightly. The 2011 Volt had no "kWh Used" number showing on the energy usage screen. GM chose to incorporate a "kWh Used" display on the 2012 and later Volts. Perhaps they should also have clarified in the manual that the kWh Used readout is a net calculation (grid power used, less regen put back into the battery while driving on grid power), not a meter readout.