Hybrid vs EV mode

For mixed highway and city driving the question is the amount of fuel used by charge mode per EV mile generated under various MPH, topographies, and weather conditions vs. the amount of fuel used by hybrid mode in stop and go driving conditions over an equivalent mileage. What ratios of fuel use will be acceptable or desirable under these various conditions.
Was this statement easy to understand? Looking for ways to explain this to those with no experience with hybrids or plug-ins.

 

The engineer said it will take between 1/4 and 1/3 of a gallon of gas to charge the battery from Ev-empty to 80% charged, presumably depending on conditions. That makes sense.

 

If that's not a BEV, why not share by taking the garage every other day for each?

 

Just noticed that word "available" before Predictive Efficient Drive! A slightly sneaky way of saying that it won't be on all models.

Disappointing!

Anyone any info as to which models will include it?

Posted via the PriusChat mobile app.

 

Interesting, let's do some math:
Assuming 44 MPG with charge compared to 54 without.
1/4 to 1/3 of a gallon - lets take 0.29 as middle point. then:
X/44=X/54+0.29. Solving gives X=68.9 miles.
So, for the assumptions above it will take about 66-70 miles to get the battery from hybrid level to 80% full (80% of Toyota full or about 20 miles EV).

 

That's twice as fast as a 240V charge.

 

Yes, maybe the 80% limit is due to the higher rate?

 

Or due to saving a little space for regeneration.

 

Premium or Advanced only, not the Plus.

 

But not as efficient.

Likely this. The pack is still only air cooled, and fast charging is heating it up. Then the slower rate to fully charge to pack might not have been too inefficient for Toyota engineers.

 

I would not rule out some room for regeneration. Maybe both?

 

Some more maths:
The 0.29 gallon times 54 could have given you 15.66 miles when you would have used it for driving. What you get via charging the battery is about 20 miles EV. So, is there some mistake here? Or is this way of operation giving you 25% for free?

 

I would think the buffer of battery capacity left when the car is fully charged is enough to handle any extra from regen braking. Leaving the avoidance of battery overheating and worse efficiency hits the most likely reasons.

From my rough calculated speculation, going 20 miles on Charge mode EV uses a little bit more gas than going the same distance in Hybrid mode. There are variables that can't accounted for now. Such as how Charge mode might effect Hybrid mode efficiency beyond the fuel burnt for charging, or how efficiently EV miles are used, like avoiding warm up on multiple short trips.

 

But there is no buffer, that is the meaning of 'fully charged' it is the highest level permitted by the system.

 

And the system's 'fully charged' is below that of the cells' full capacity.

I think you had calculated that the portion of the battery used for EV was 6kWh or a little higher. The pack is 8.8kWh. Subtract out 1.5kWh for hybrid operation, and there is still nearly 2kWh of capacity. Some of that capacity will be charged, because I can't think of any battery chemistry in which being fully discharged is a good thing for longevity, and it won't be fully charged for the same reason. For Li-ion, it is best to keep them at 80% charge.

So there is empty space for some regen braking. Otherwise, a fully charged Prime would be incapable of regen braking at the very beginning of a trip.

This raises another reason for only having Charge mode go to 80% SOC. There might be a maximum amount of battery charge in which the system won't allow Hybrid mode to be entered. European spec i3 REx have to drop down to 75% charge before the range extender can be turned on. In hybrid mode, energy can be going from MG1 to the battery at a steady rate. Having some of the EV charge used before entering hybrid mode can eliminate this charging from overstressing the battery's overhead capacity.

 

You are confronting Toyota engineer (who said that 1/4 to 1/3 of a gallon will be used to generate 20 miles of EV) not me.
I feel that something is wrong with your logic but cannot pin-point it immediately. The 0.29 gallon was spent on top of what needed for moving the car, it is marginal load, if the car (charge off) could move further to the said distance on marginal load only it would do this further distance at an efficiency much higher than 54 MPG.

EDIT: added
Let's look at it from another angle:
0.29 gal worth 0.29x33.7=9.77kWh.
The usable capacity (usable for EV) of the pack is ~5.72kWh (my assumption of 65% of total), 80% of it is 4.6kWh.
Efficiency of this forced charging is then 4.6/9.77 or 47%.

If 1/3 gal is used then it's efficiency is 41%
If 1/4 gal then 54%.

 

@Trollbait , Sorry I give up.