Prius PHV 2017 (aka Prime) 3+ year Charge Data Summary

Very nice! Thank you for sharing this data.

Just one quick question and suggestion. Are the "max charge" shown in each cell for the month a single charge event or average of multiple charge events on that month? If it is just a single charge event highest in that given month, it may not be a real representative of your traction battery charge. The best way would be to average all of the full charges and only full charges (i.e. not including partial charges) under similar condition (such as same use of climate preconditioning or battery heater or cooler).

And on your Grand Total cells, you just filled it with the highest charge in the given year. This again should be average of all 12 months. If you take the average of 12 data points, the number looks like this. That is 4.4% degradation of the max charge amount in Yr3 compared to Yr1.

 

Yeah, that's the problem. You have to log manually which one was from 0 EV range to full and which one was the partial charge. I did a similar data collection on my 2017 PRIME but did not log all of the charges to make the analyses complete. The graph below is the monthly average of all full charge kWh I have logged during my ownership of the 2017 PRIME for 30 months. I did not collect data almost the whole year from 5 mo to 17 mo making the downward trend incomplete.

A single max charge could throw off the data trends. I had my 2020 PRIME since March. I have not been driving much, thus I have only done small numbers of full charges, but the highest charge I had was 7.13kWh for a full charge for unknown reasons. This is an outlier of the data I would not want to include in the analysis. Also for cooling the battery, it is true that the battery cooler function cools down the battery using climate control BEFORE the charging event starts, however, I have learned recently that even during charging, the battery cooling fans run to cool the battery. If the temperature inside of the car is hot, the fan seems to run harder. I noticed my day time charge for an empty to full took ~0.2kWh more to finish charge than a night-time charge.

 

Yap, that will throw in another variable. The big one that is. You might be interested in reading @PiPLosAngeles analysis in this thread. He is trying to eliminate this variable of HV depleting (or regen adding ) 0% EV SoC on the display. From his somewhat small numbers of data points, he found that, in his 2017 PRIME, there has been no battery degradation in 3 years from the full charge amount he is reading for strictly from 0% to 100%.
What is your miles/kWh (total average electricity consumption) on the "Drive Monitor 2" | Page 12 | PriusChat

 

My approach has been to film the same drive under the same conditions year after year. I just did the capture this morning for year 3. EV distance was a little over 30 miles... matching the previous drives.

That means based on observations so far, you get the experience of consistency. There is the possibility of a degradation buffer, extra capacity only accessed as the system detects reduction. Whatever the case, that is still a result in excess of the EPA rating.

Crude evidence of this is the calculation from my own charging. 6.0 kWh has been the max I typically can squeeze in, without conditioning. 72% capacity is max for observed EV delivered via plugging in. That doesn't account for losses from the charging process or gains from regeneration though, which a rough guess would be 10%.

That would equate to a true 5.4 kWh for
EV usage per recharge... which is quite a bit less than one would expect from a 8.79 kWh capacity battery-pack.

Others reporting more kWh per charge may have a combination of less efficient charging and the possibility of different tolerances in the software for their vehicle.

Long story short, we may never find out. Knowledge, like long-term strategy, is too valuable to disclose. They need a competitive edge.

 

That doesn't actually add up to 8.79 kWh though. Based on the basic tools we have for measuring draw & consumption, there appears to be a small amount missing. True, it could be some other property of rechargeable batteries we are not aware of. But then again, we already know about the difficulty of measuring conversion, vampire and storage losses. We aren't the only ones making that same observation/speculation about automaker approach either.