PLEASE HELP! Home Charging Options for Prius Prime

There is some evidence from a current Prime owner that this won't happen anymore. Can't find the post right now.

 

Yes. As I state each time Charge-Mode is mentioned, there is a clear advantage to using it on long trips. Far less horsepower is used to maintain a cruise on a highway than what the engine has to offer, which means the introduction of a minor load won't result in as much of a penalty as one would think. It's counter-intuitive, much like how the hybrid system works without a plug. Extra load can actually result in a gain. That's how higher MPG is achieved. So with the plug-in, once you get off the highway, having a recharged battery presents efficiency opportunities which would otherwise be lost.

 

And I still think that same approach would work even better on low-speed surface streets that don't have a lot of stops. The engine is barely working on those and a little extra load will likely increase thermal efficiency. If you get to use that power later to prevent warm up cycles or on slower, shorter trips where you won't have to run the ICE, overall efficiency could be improved.

 

It's not only a matter of possible efficiency gain, there is also the environment aspect: better to use a bit more gas on the highway (with possible better efficiency) in order to have EV for city drive later on - where your tailpipe is very close to the noses of people. Prime is very clean on HV mode but zero tailpipe is cleaner.

 

On a work related trip from Sacramento to Stockton and back last Friday, I did a "test" of a way to use the Charge Mode: I agree with Lee Jay that this mode is probably best when the car is traveling at lower speeds. All cars are less efficient at higher speeds due to air resistance, rolling friction, etc. So, I started the trip with a fully charged battery and then fully depleted it on the freeway. I traveled in HV Mode thereafter. On the return trip home and after encountering lower speeds in Sacramento, I switched to Charge Mode. I used the Nav to determine the distance from my house and when the EV range increased to within a couple of miles of the distance to my house, I switched back to EV Mode and ran the remainder of the trip on battery. I didn't use that method approaching the destination in Stockton as it was just a couple of miles from the exit.

So some calcs: 119.9 miles at 66.9 mpg means I used 1.79 gals of gas on this trip. If I assumed that I traveled the first 25 and last 11 miles of the trip on battery, that means 119.9 -25 -11= 83.9 miles were in HV mode using the 1.79 gal of gas. This comes out to 46.8 mpg in HV Mode, all of which were on the freeway. Most of the trip on the freeway about was at "high" speed except for the last 20 or so which was at 50 mph or less and about 11 of those were in EV mode. Only about 11 miles of the entire trip was on "surface" streets. Is 46.8 mpg in HV "good"? I'm fine with it, but I would like to hear of the best strategy in using Charge Mode. I put on more than 21,000 mile per year on my car (my Gen2 ended up with 252,000 miles) and most of it will be in HV mode, so understanding the best way to manage the different modes (EV, HV, and CHARGE) to maximize my mpg will be helpful. Your thoughts are appreciated.

 

Yup, finally got mine to work, took a while to fihure out how to update my Entune App on my phone because I had a 2015 Prius base model so no remote Apps. Once I entered my contract ID into the App I was good to go.

 

of course, the 25 ev miles are from a standardized test. ymmv. if you need more, consider volt or other.
as far as force charge, it's mostly a gimmick and bad for mpg's and thusly pollution. but if you had a long hill climb coming and little charge, it might be helpful. also, some euro cities don't allow gas, so it might help there.

 

You're asking for quite a bit of conflict making generalizations like that. I'll be bumping heads with you on a regular basis, pointing out that USED WISELY there can be circumstances in which you will see an efficiency gain (and subsequent emission reduction) from using Charge-Mode.

This will be a education effort for newbies, very much like what we did back when Prius was new to most people. The assumption was made that more electric-only driving was better. We know that's not the case. The engine can indeed encounter situations of lower efficiency though, where a benefit can be realized by adding load.

Your use of "mostly" should be changed to "except on long trips without plugging opportunity". After 4.5 years of driving a Prius PHV, it's easy to see how those distant drives on the highway are always followed by running around with the Prius upon reaching your destination. In that particular circumstance, I know for a fact there will be an overall improvement from taking advantage of Charge-Mode.

In basically all other driving situations, I don't envision recommendation opportunities. So, I'm with you in that respect. But with a vague "mostly", expect routine replies provided clarification. We're at the early stages when assumptions & misunderstandings happen. So, extra care will really be a boost to our desire to help. Best of intentions...

 

I'm skeptical -- really, really skeptical. The Prius Atkinson engine already is quite efficient to below 15 kW and the native programming has no problem cycling a little bit of battery charging to optimize engine efficiency during highway driving*. Force charging does not give the programming the option when and how to optimize ICE use. That said, it will be interesting to see what SOC the programming levels out at in HV mode on an extended drive. My presumption is that a Prime will have more capacity than a regular Prius, thus allowing more native fine tuning of engine efficiency.

However, I look forward to good comparison data in the future you may have to share.

*I think most people have come to realize that best MPG is obtained through non-aggressive driving behavior rather than trying to out-Prius the Prius. The common examples were drivers who would force EV mode down to a very low SOC and then catch an extra penalty overall when the Prius was forced to recharge the battery at an inopportune time. This force-charging is I think the other side of the same coin.

 

Charge at home and then drive to your destination in HV mode, thereby leaving your EV miles for your destination.

I'll be quite surprised if Bisco is wrong; I too think it is a gimmick, just like remapping the fuel pedal is a gimmick.

 

What we really need is wireless charging. I have Two outlet in my garage one for the door the other in the wall. I be fine with the low charging. I have never seen a charging post at the dealership I do the maintenance.

Posted via the PriusChat mobile app.

 

And when it's cold or at <5kW due to being on a surface street at 35mph or on a gradual downhill on the highway?

 

Pulse then glide. I suspect that the Prime will imitate P&G natively in HV mode if the battery has enough charge in these very low power demand states by turning off the engine and powering with the battery.

The native programming already handles this condition very well by cycling the engine on and off; and I bet it will do even better in the Prime with a higher speed limit for engine off and more battery capacity at SOC equilibrium.

 

I have been getting 11-12 miles EV in my PIP but I live in Florida where it is flat and right now the weather is in the 70's so no heat or ac needed. This is ideal conditions. I suspect in the summer when I'm running AC I will be 8-9 miles

 

Having extensively experimented with the wide variety of opportunities my Prius PHV has presented of the past 4.5 years, those assumptions being made here are a clear indication of head-butting to come.

The reason is simple: over-simplification with a blanket dismissal.

Notice how we quickly went from "mostly" to never?

 

Force charging en-route Vs HV and EV miles at the destination.

'Just Drive it' ;-)

 

That's practical at times, but not always especially in traffic. Increasing your engine load from 5kW to 10-12kW will increase thermal efficiency a lot, and make using those miles at a later time pretty efficient.

 

The Toyota lead engineer for the Prime said that it would take between 1/4 and 1/3 of a gallon of gasoline to charge the Ev mode from 0% to 80%. 80% is 20 rated miles. 1/4 of a gallon would thus mean charge mode generated 80MPG, while 1/3 of a gallon would mean charge mode generated 60MPG. Both are pretty good.

 

<<shrug>>

The Prius is tremendously efficient in HV mode in the city in my experience -- routinely 70+ mpg and up to 90 mpg if traffic lights cooperate. Anticipating other drivers, keeping a good distance from the car in front, minimizing brakes, and matching signals are the things that matter. At 70 mpg in a Gen2 or Gen3 Prius the motive energy after combustion is around 170 Wh/mile. EV driving is not going to be much if any less.

The only non-trivial or extreme corner case reason this notion of EV in the destination city after a long trip has merit that I can think of is to reduce engine warm-up routines. And as I said earlier, for that case just drive in HV from the start of the trip and leave the battery charge for the destination.