I have been escalating an OnStar/MyVolt.com issue where a large kWh data spike was reported to OnStar coincident with when I had my battery enhancement done. Others have reported the same issue.
Today, I received a phone call from the OnStar R&D Project Manager responsible for this software explaining what happened and what they are doing to address the situation. Here is what I was told.
- There is a hardware sensor/counter in the Volt that tracks the total kWh drawn since the car was built.
- The most recent value of this counter is kept separately for use in later calculations.
- When a charging event completes, the most recent value is subtracted from the counter to determine the number of kWh drawn during that charge event.
- The value of the counter is then saved off as the new most recent value.
- The SW update required to add support for the new battery coolant level sensor also resets the sensor/counter in the Volt that tracks the kWh drawn by the car to zero.
- At the completion of the next charging event, the previous value (a large number representing the total kWh drawn since car was built) is subtracted from the counter value (zero since it has been reset).
- The value reported for this specific charge event is a large negative number.
- The MyVolt.com site does not expect a negative number for this value and simply discards the minus sign leaving a very large reading for this specific charge event.
- This large value is shown in efficiency graphs and is also included in the total kWh which is used to calculate kWh/100 mile figures and other efficiency figures.
- This issue will happen for everyone that has the battery enhancement and related SW update.
- Back office software changes on the MyVolt.com site will be made to address the issue where negative values for kWh drawn are reported.
- If a negative value is seen for kWh drawn during a charge event, that event will be disregarded and the data not reported on MyVolt.com and not used in calculating kWh/100 miles and other efficiency figures.
- When this new back office update is rolled out, the large data spike will no longer be reported and incorrect values listed for kWh/100 miles and other efficiency figures will be calculated correctly.
- The proposed solution is being reviewed now to insure the proposed fix is robust.
- The Project Manager believes that the fix will be implemented by the end of July and rolled out on the MyVolt.com website a couple of weeks after that.
I am encouraged that they believe that they have located the root cause of the issue and that there appears to be a reasonable explaination for the behavior seen. While it seems like a long time to implement the fix, I am glad that they are taking their time to insure that this problem is addressed properly and completely.
It seems like it would make sense to correct the Software Update to support the battery coolant sensor to not reset the kWh counter, but I have no information on if this will happen or not.
We shall see how this plays out when the new MyVolt.com software rolls out in August.