EV Driving Ratio Display

I recently went on a 291 mile trip through the Sierra Nevada Mountains to Virginia City from the Sacramento Valley. The EV Driving Ratio display said 26% EV which sounds about right as I switch EV/HV as appropriate for the terrain. Lots of EV going downhill to charge the battery for the flat lands.

The EV Driving Ratio display only shows 1 kWh of electricity which approximately corresponds to the difference in SOC (full = 85%) at the start and 50% at the end of the trip. (actually that would be about 1.5 kWh but it only shows integer values).

My conclusion is the EV Driving Ratio kWh value only shows what you charged from the power line and does not include any regeneration. The 4 gallons as opposed to the actual 4.8 gallons is probably due to the integer value display.

Here is the EV Driving Ratio display


Here is my Trip Log

Note: I realize the MPG display isn't accurate (about 1.5% high) but that's the convenient way to get all these values

 

That's the whole point of the posting. I believe that the kWh in the display is only electricity that you get from the power line. Whereas the EV miles are all miles you traveled actually in EV and using the battery to power the car. In the case of this trip almost all of the EV capacity came from regeneration not the power line.

 

Hence the elevation column in the trip log. Over 50% recharge from Donner Summit to Reno and Virginia City to Reno. Almost 100% recharge from Donner Summit to Sacramento Valley.

 

We don't have an elevation monitor? That's terrible. Of course its the downhill... the elevation just gives some idea of the terrain for the various legs of the trip.

This is why the PiP can get better mileage than the non-plug-in for some trips under similar driving conditions.

 

I suppose the purpose of the kWh on the display is to provide power line charging information for folks that don't have a watt-hour meter. It clearly reports power line kWh and not regeneration (used to run the car) kWh.

 

What calculations off, how?

 

Yes, that is difficult, virtually impossible, using the available information form the display.

I made several runs over a few day period where I started with a full charge, made short trips in EV only, then a full recharge measured with a Kill-A-Watt meter . Having to make more or less stops at red lights makes a noticeable difference for the same trip. The results are shown below.

SOC Chg is the change SOC from full (85%) to SOC for the kWh shown at the end of the trip.
kWh/100mi is the EPA calculation where you add 0.2 gallons of gas per 100 mi even though I didn't use any gas.
The EPA says the Prius Plug-in gets 95 mpge so I am doing a little better than that. I live on a hill so it costs going up but the regeneration going down really helps.

The EPA information is here Compare Side-by-Side