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0-25 mi = Drives like an EV
25-640mi = Drives like a regular Prius (on gas)

You can also adjust the driving mode while in motion. For example, on long trips I use the EV mode for stop/go, city driving, or accelerating onto the highway, then I switch to gas mode while cruising on the highway. PHEV's really are the best of both worlds.

 

I use the ICE for this if it’s already running. At bigger throttle opening it can be more efficient due to lower pumping losses.

 

Hmmm, I never thought about that. I presumed that since gas engines have an RPM sweet spot for efficiency, you'd want to keep them at the point as much as possible (i.e. constant narrow speed range). I may have to test this further to see which is more efficient.

 

I use Hybrid Assistant and keep the engine RPM at 3,000 RPM or lower. The instantaneous fuel economy doesn't dip too low. I’ll have to gather some data on the next trip. Around town my ICE rarely runs.

 

I think that PHEVs are limited for the reason that they presently (at least in TOYOTA's case) are a very economical vehicle anyway, but have a limited EV range for those who can utilise it. But, they're dragging a much heavier battery, often forego a spare wheel, in PRIME's case, even the back middle seat is deleted - so they're not as practical, and the extra weight must be an impost on potential l/100km when not charged up. PHEVs have bigger battery capacity, though than the earlier ones did - more because batteries are more compact.

 

Atkinson Toyotas have evolved to throw a broad band of good efficiency, it may be difficult to find the right RPM-BMEP coordinates...

 

Don't forget - noonm is driving a PRIME - quite a different situation from PRIUS.

 

In HV mode it is essentially a Prius. Same engine.

 

HV Mode? What is that?

 

The prime is growing back its 3rd rear seat and getting carplay in the 2020 model. The weight isn't all that important its about 300 lbs more than the non-plug prius but gets the same fuel economy. The tesla model 3 is much heavier but handles better, you can take care of even more weight with suspension.

Compare Side-by-Side



This year the prime gets about 1/3 of all prius family sales in the US. Next year with the slight redesign it may get half. The car was not really designed for the 7 cubic feet the battery takes up though, but it is a better compromise than the ford fusion energi. Between the corolla hybrid (used to be auris in europe), camry hybrid, and rav4 hybrid most of the US and European based sales have left the prius family. The aqua (prius c), and prius are still number 2 and 3 best selling cars in japan. It may be time for toyota to make a dedicated phev for the US, Europe, and China, perhaps a slightly taller, prettier, longer electrical range version of the prime. Keep a hybrid maybe slightly different body for japan (and probably Australia and New Zealand).

 

This is the mode in a Prime where you tell it to run the ICE and basically to become a Prius. If you do this, it will generally leave whatever charge is in the traction battery in reserve for EV mode at a later time.

 

Any engine with variable valve timing can have a wide 'sweet spot'. The Prius, and other well designed hybrids, have the engine run as often as possible in that spot.

The only difference is in the battery size, which actually helps the Prime get better hybrid fuel economy than the Prius, despite the weight increase.

Hybrid mode.

The Prime loses more cargo space when compared to a Prius without spare tire, than the C-max Energi did. The Fusion suffers because it didn't have the biggest trunk to begin with.

But the Fords are first generation PHEVs. Toyota could of, and should of, done a better job packaging the battery in the Prime.

 

Where should it be?

 

They could have made it flatter with less height. In my prime, there are narrow spots on the sides of the traction battery compartment to put things like the tire goo kit, tools, etc. That says to me that there is definitely room to spread the battery out further.

 

IMHO the decision to make it air cooled and design the car for the hybrid first kind of dictated the design. I don't think they did a bad job using those constraints but they definitely can do a couple of things to fit a higher energy battery in the car.

A) Make it a little taller and spread out the air cooled battery or
B) Use liquid cooled pack

The most energy dense battery pack is now in the tesla model 3 long range. It is liquid cooled and is only 3.5" (8.9 cm) tall and a volume of only 6.6 cubic feet (252 liters) for a pack with 9x the energy of the prime. The radiator and coolant take up space in the model 3 but this probably doesn't take up much more space than the engine radiator and coolant already do in the prime. BMW's liquid cooled 12 kwh pack takes up only half the space of the primes 8.8 kwh air cooled pack.

 

There may be apparent room, but there are certainly design considerations. Space for cooling fans and ducts, crash survivability, ability to get the battery in/out of the vehicle, battery cell size, available space in the car, etc. If you look at these screen captures from one of the Weber Auto videos, you can see that the pack is already hard up on the wheel wells.

 

But if you add a third cooling system (already has one for the inverter and one for the ICE), where is this going to go?

 

We'll see if they do put a higher capacity battery in there - this will be driven by market demand. I don't need a bigger battery, which would add more weight and cost more. I get 99% of my local miles on EV as is, as do many others. And, with the fuel efficiency of the Prime on ICE, even if my battery gets exhausted, it's not that big a deal. None of the PHEV competitors can match the fuel efficiency after battery exhaustion.

 

Tesla uses the same coolant for inverter and battery. It will add to costs, but toyota's cost for air cooled batteries are much higher than tesla/panasonic or lg for liquid cooled batteries. Inverter cooling needs will also go down when toyota switches to SiC (Silicon carbide) for power electronics. This can fit under the hood possibly with a pump near the back for the battery.

I think its more about cost than anything else that would limit the battery size. With a higher energy battery it can have lower power density. Weight is not going to change appreciably. The speculation is lg at the pack level is about $190/kwh which would make a 12 kwh pack cost toyota about $2300, tesla's pack is even less expensive. That would add about $3000 to cost (that is to toyota not the customer) for a smaller liquid cooled 12 kwh pack plus cooling system, that would increase range about 35%. Liquid cooling will help even more on very cold or hot days. Toyota's current cost are about $3500. I'm not sure if toyota is able to drop the cost their air cooled pack that much and maintain reliability.

 

Given the long history of Toyota hybrids with air cooled batteries, I don't see them shifting to liquid cooled unless they are going to significantly increase battery power density. That would likely come only with a BEV.