2023 Prius Prime EV Range

soooo...prime or clarity?

 

I find that the best time to buy a Prius Prime is in December: (1) You get the nearly maximal factory rebates. (2) You get the latest model year, with no immediate model-year depreciation. (3) You have the minimal amount of wait for the federal tax rebate.

 

You're welcome!

For example, when you're driving on a freeway, every time you go through a grade separation, you're likely going over a dip if you are going under a bridge and a hump if you are going over a bridge. Even if the freeway is on an entirely flat land and even if you keep your speedometer speed constant, there is a lot of acceleration and deceleration due to gravity due to these dips and humps for grade separation. In effect, this is no different then going through traffic lights gently in city driving. Therefore, your regenerative braking is even working during the perceived cruising. It's not to mention that quite often you need to adjust your speed for other cars, which kicks in regenerative braking. This is why I don't observe a negative effect of traffic lights in city driving if I can manage to go through them very gently. mi/kWh on the eco diary slightly goes down and then comes back to the same value while very gently going through the traffic lights. You can do the same experiment going through the grade separations on a freeway on a flat land.

 

This is a function of driver style. Your description is of someone going constant speed. Others will go constant power, allowing the car to slow slightly on the uphills and speed up slightly on the downhills.

Only the aggressive drivers, yo-yo drivers, and tailgaters should be getting in regen braking under these conditions. Efficient drivers allowing safe following space should not be getting into regenerative braking under these conditions, but can stay of the positive side of power production virtually full time.

With safe follow distance in non-combat driving on flat-ish roads, only the aggressive / yo-yo / tailgating drivers should be getting in regenerative braking with any significant frequency.

Calm down and back off, and you can almost eliminate the highway regen that you speak of. Unless your driving is in what is effectively an automotive war zone.

 

Of course, regenerative braking constantly works even in normal driving. If it were only for aggressive driving, it wouldn't even be needed, as you are using your friction brakes in that case. In fact, regenerative braking shines most during gentle driving. An aggressive driven Prius approaches the limit of a regular, nonhybrid car. Good luck driving constant-speed or constant-power on any big-city freeway.

 

That sounds like yo-yo driving, a pattern that is best avoided.

Most days, good efficient drivers should be able to go their full highway distance without touching the brake until getting to the exit ramp. Don't be like the drivers (including my past carpool mates) who just had to touch the brake once or twice each mile, whether they needed to or not.

Not all days are like this. Congested stop-and-go conditions make mincemeat of this effort. But that doesn't represent most of my driving days.

In my area, most of my days I get by just fine by simply backing off on the gas pedal, without touching the brake or even letting the HSI gauge go left of neutral. The propulsion force stays positive, even if reduced, not needing to go negative.

And even on the days I do need to use the brake pedal, it is just sophistry to compare that minor slowing to the full stop of a traffic light.

My constant-speed vs constant-power comment was about the bumps and dips example you brought up, not about changing traffic speeds. The later does require power and speed changes, so requires adequate following distances in order to avoid continually braking. But a great many drivers refuse to leave adequate or safe spacing.

 

I think my observation that very gentle going through the traffic lights having no effect on the EV range has two main reasons:

(1) We are not looking at the absolute efficiency of regenerative braking but the efficiency over the baseline, which is cruising. You would still experience the same drivetrain losses if you weren't accelerating or decelerating. Therefore, the losses are mainly due to the charging efficiency of the battery and circuit.

(2) When you are accelerating or decelerating, your average speed is one half of the cruising speed. Since the viscous drag is proportional to the square of the speed, the energy requirement around traffic lights reduces to a quarter of that of cruising. This huge reduction in the energy requirement easily offsets what is lost during regenerative charging or other energy loss during regenerative braking. In fact, I did witness this: going through traffic lights seems to typically increase mi/kWh instead of decreasing. This is probably the solution to the puzzle: reduced speed thanks to the traffic lights may even increase the EV range, let alone decrease it.

In any case, this is something I have already verified through observation of mi/kWh on the eco diary, and I am confident that going through the traffic lights very gently has no negative effect on the EV range and can even have a positive effect because of the point (2) above.

Last but not least, I am currently the fuel-economy champion on PriusChat. I also get a ~ 40 miles round-trip EV range in city driving. I must be driving fuel-efficiently.

 

Being retired and living within 20 miles of our most of our trips I've found our 2017 Prime Advanced runs on EV power about 75% of the time. The other 25% of the time we travel beyond EV range, then between gas power and occasional PV power it registers 80-85 mpg. Also living in the flat lands of North Carolina probably helps since we spend very few miles climbing hills. After 5 years of ownership we've only accumulated about 23,000 miles.

As for a new Prime or Honda. I had one Honda and didn't like it, so Toyota for me. I would be tempted to upgrade to a new Prius Prime if/when we see a new model's EV range get extended to 60 miles or more. That EV range would cover 95% of all our travels. Otherwise I'll continue to run our '17 model. Our Prime has been the most economic vehicle we've ever owned.

 

I unfortunately don't have time to go through the 6 pages of replies in this thread right now, and someone may very well have already mentioned this, but have a look at these requirements for incentives for phevs in california:



If anything would get Toyota to give the next-gen Prime 35 miles of electric range, it would be CARB. I think many on here would agree.

 

Unfortunately that likely won't happen - without mentioning that it would massively lower fuel economy in HV mode thanks to the sheer size and weight of the plug-in battery. The highest-range plug-in hybrid is the now-discontinued Chevrolet Volt at 53 miles.

I would hope that no one considers the BMW i3 Rex a viable plug-in hybrid, because yes, it technically has 120 miles of electric...followed by 80 miles of gas. without mentioning that you're not supposed to use the gas engine unless you absolutely have to to make it to a charging station...yes a charging station, not a gas station...

That all said, if there could be a vehicle that magically got 70 miles of EV and 50 MPG, I'd love that. But that's just what it would be - magic. Not going to happen for a long while...

 

The Prius Prime's battery weighs in at 265 lb, which is 10.6 lb per mile of EPA range. Bumping the car's EPA range to 30 miles would require adding 53 lbs of battery. 53 lbs is not going to have any discernible impact on mpg, especially not one that would offset the potential financial benefits for California buyers.

 

Add to this there are much lighter kwhr/lb batteries on the market that are volumetrically smaller as well

If Toyo were to use one of the smaller lighter configurations they might get more capacity into less space and have room for a spare

 

I was just getting ready to add that Toyota's current battery has a specific energy of 73 Wh/kg. Even my Panasonic 18650 cells I use in my flashlights are in the ~275 Wh/kg range. If Toyota used those cells they could triple the range, leaving ~50 lbs for other parts of the battery without adding a single pound. Tesla has been using commercial lithium cells to good effect for a long time.

 

i wonder how much battery stock toyota has, and access to other manufacturers

 

When comparing battery energy densities, do try to keep track of just which chemistries are being discussed and compared. There are very many varieties within the lithium-ion family. The most energy dense versions (by volume or mass) tend to not be the ones best suited for long lived motor vehicles in outdoor environments, but rather for shorter life appliances (hoverboards, laptops, cameras, etc.) expected to erupt into spontaneous combustion at ordinary indoor temperatures.

Unfortunately my best detailed inside information is well past its NDA expiration, so is too outdated to be useful now or to go dig up for a refresher.

 

They are vertically integrated and their supply base can’t support many EVs

Chevy Bolt (for comparison) is 150 wthr/kg (if we use the actual capacity and not the amount Chevy let’s you use)

 

I'm comparing the total 8.8 kWh of the Prius battery vs. it's 265 lb. weight.

And as far as the suitability of 18650 batteries for EV use, that's why I pointed out Tesla's use of them without issue.

 

My point is the Bolt isn’t exactly leading edge and even then…

Using “Bolt” batteries the Prius would have an 18kwhr battery for the same mass