Total Kilowatt Prime can accept from a level 2 charger.

8.79 kWh is the total capacity of the battery, not the usable. That full potential of the pack is avoided for longevity. Either extreme will accelerate aging. In Prius Prime, that equates to EV electricity coming from the span of 12% to 84% in terms of charge-level. The resulting 62% comes to 5.45 of potential for charging, not including conversion losses or pre-conditioning.

So, what you have observed is a reasonable outcome. It will vary from time to time, depending upon temperature and what level HV capacity was upon plugging. But in simplistic terms, somewhere in the 6 kWh measure is normal.

Lastly, you'll find that most apps tend to grossly underestimate range in terms miles. Not sure why.

 

OK, you are correct on 12% to 84% according to the Hybrid Assistance. But that comes to be 72% of battery SOC or 6.33kWh (8.8*0.72). Where is another 10% (0.88kWh) coming from if not coming from the wall (6.33-5.45=0.88)?

 

Yup, I already caught that math error. It seemed strange to be so low. The around 6 kWh comes variance in HV mode when you plug in. Seeing it range anywhere from 9 to 16'ish provides a squishiness of over 0.6 kWh. That means we really can't nail down any expectation beyond just saying the "full" capacity is around 6 something. It's what happens when you empower people with data...

For example, this charge the other day took 5.96 kWh. Notice the periodic drops in my graph verses the absence in the original post.

View attachment 185659

 

Yes, I have seen on other threads someone with SOC as low as 7-8% by Hybrid Assistant reading with HV mode after the depletion of EV SOC. Mine has been consistently 11-12% at the bottom, 83-84% at the top. I know you have stated that you observe less than 6kWh for a full charge. I guess OP's case is yet more extreme low for a full charge. As I have told you before, my full charge with L1 has been always over 6kWh (average ~6.5kWh) measured by a Kill-a-watt meter.

 

And the lesson learned from that was... ?

It was to not get so hung up in those details. You provide a basic example, then teach others how to find their own data themselves. That's why Prius has always been so compelling. It draws owners in. They end up discovering more and they drive more. For example, point out what Hybrid Assistant has to offer.

 

Can't say if what I learned was the correct answer, but I like @bisco explanation that traction battery maybe not as homogeneous as other parts.

Even if I accept variations in numbers reported for the full charge by various owners, I am still puzzled with the numbers presented by my car that do not fit the observations I make on my car. For example, my observation of the value for a full charge by L1 is 6.5kWh. This fits very well with the number Hybrid Assistant report for the full EV range of SOC 84%-12% (6.33kWh). But, another data from the car, the daily miles/kWh does not match with either of them. From actual miles driven on EV mode and miles/kWh data from the car, my full EV range SOC always comes out to be 5.4-5.7kWh. I have no explanation for this discrepancy.

 

What does the miles/kWh value actually represent? Is it overall efficiency or the measure of efficiency only while you are moving? In other words, sit somewhere parked for awhile. Does the value go down for the trip? We know that Hybrid Assistant provide the option of display either of those values.

That's why reporting a number is so screwy. If a person is picking up their child from school, sitting there will the system on but windows open would still consume some electricity but would be far easier to overlook than if they had the A/C or Heater running. That's an exaggerated example of a long commute with lots of stoplights, but still easier to measure than the randomness of red-lights and stop-signs. And of course, all that varies with temperatures.

In other words, those of us with extensive hybrid history have seen the same efficiency-measure problem play out over and over again. You never can nail down a solid answer to provide new owners or an expectation with prospective buyers. Making matters worse, we have the added problem of different generations having profoundly different software, hardware, and battery.

The song "Let It Go" comes to mind... hence, just teaching those interested how to retrieve that data for themselves. And yes, I will be doing exactly that with my videos. Teaching moments...

 

Yap, I agree with you wholeheartedly.

 

We have a diverse audience too. Think about how confusing matters will get when RAV4 Prime hits the market. It's difficult enough just trying to figure out how each of our own Prime behave. (That's for always being constructive with our discussions.)

I'm scrambling to get ahead of that, creating material to teach the teachers with. My best friend is already going nuts, wanting to get a RAV4 Prime the soonest he possible can. I'm hoping to jump on the opportunity from that to get some real-world data right away to share. Anywho, here's the latest in that effort...

https://priuschat.com/posts/2994296/

 

Something else to consider when evaluating energy measurements is the accuracy of the device making the measurement. I have a net-metered 6.5kW solar system with an analog 'revenue grade' kWhr meter on the AC side which was required by the state agency (NYSERDA) who provided a subsidy. The SMA solar inverter digitally logs the same thing and the inverter's total (~40 MWhrs) has been consistently 10% higher than NYSERDA's meter.

These relatively low cost devices that measure kWhr are likely +/- 20% if they lack temperature compensation and/or a precise standard voltage used for internal calibration. My SMA inverter has both, and it's off 10%. 'revenue grade' meters are -3.5% to +2.5% if I recall.

I'm a Prime newcomer and plan to get a cheapo (<$20) kWhr meter from amazon to log my home charging. I have an electrician friend who may be able to lend me a revenue grade meter (hopefully in exchange for beer...) I'll report back if I learn anything from an intercomparison.

 

And there is the observation that with L1 (120V) charging, people are seeing around 6.5 kwh for full charge from the wall, but closer to 6.0 kwh or slightly less on an L2 (240V) charger. At least part of that may be due to losses in the charger during the twice-as-long charging cycle.

 

Some EVs are really good at estimating remaining range based on driving conditions, heat/ AC usage, etc. I think the Chevy Bolt is a good example. It has a realistic estimate and a lower bound. The Prime is absolutely useless. The guess-o-meter doesn't consider huge known factors like battery temperature. Just an average of your last few days of driving. And if you turn on the heat or AC it deducts an arbitrary amount whether it's fan only or max AC. The eco climate indicator is similarly bad, using mostly only the difference between interior temperature and the setpoint, no matter what you actually have the fan set to. For example in the summer 76 degrees and 1 fan bar might give you a good score, but 66 and 1 fan bar will probably give you a bad score, even though the compressor is probably running at the same speed either way as it starts to cool off. In the long run a higher temp will use less energy, but the arbitrary "score" makes it seem like it's 5x as much.

They need to give people useful tools to understand efficiency.

 

KISS is the audience being targeted.

Also, keep in mind that margin-of-error is exaggerated when the total quantity is significantly smaller.