Best mode for long distance driving?

What is the 'charge mode' advantage in this situation over just looking for a gas station?

 

EV-Auto mode tries to use the most efficient energy source at that instant, be it gasoline or electricity. This is how EV mode worked on the first-generation Prius Plug-in. But users complained about the ICE turning on "unnecessarily", so Toyota changed the programming in the Prime to provide both a "most efficient power source" mode and an "EV only unless you floor it" mode. They even added a "Charge" mode to allow the ICE to recharge the battery, even though there are only few situations where the conversion losses are mitigated by other factors, which most non-sophisticated uses are not likely to sort out.

 

EV mode is even if you floor it (most of times).
There is another reason for EV Auto in the Prime and it is the available power (for overtaking and such), EV mode is limited to the 68 kW the battery system can provide, EV Auto has the full 91 kW available.

 

Risk avoidance. The car has very accurate SOC even at the low end so the driver can park safely. In contrast, gas is less precise which can lead to unsafe, involuntary stopping .

Bob Wilson

 

OK got you...I am avoiding all risks by refueling well before "low gas" comes on...

 

That is a good strategy but I like to know the performance limits BEFORE reality makes its appearance. Then I share them with the community. These are obscure and often difficult places to be but not impossible.

Bob Wilson

 

I drove from Northern Minnesota back to the Twin Cities today. Here's some real-world data from that...

charge-mode = 40.0 miles

charge-mode = 37.8 MPG

It took 38 minutes at 66 mph with an outside temperature of 64°F and a light crosswind to recharge the battery-pack form 0 to 80%. I took advantage of that recharged 25 miles of EV (estimated) to keep the engine off while making our two stops along the way and when getting trapped in weekend traffic at a major highway junction. These were the final results...

overall = 153.7 miles

overall = 60.4 MPG

In other words, just charge it. If you'd like engine-generated electricity for use later, go ahead. There does not appear to be any penalty for doing so.

 

Thank you for searching the performance limits and sharing, good to know and I really appreciate it.
Maybe better way to present it in a prescription will be: If "low fuel" indicator comes on before you had a chance to refuel...instead of: when.

 

I'm not so optimistic. <GRINS>

Bob Wilson

 

Let's assume:
- depleted battery
- 65 miles at 65 mph

There are three strategies at least:

1. HV mode for 65 miles --> 55 mpg (65 mph)
see a diagram(#80) Prius Prime Plus in my hands | Page 4 | PriusChat
on the other hand, the HV advantage is the ability to conserve the battery power

2. so called CHG/EV mode --> 61.4 mpg (66 mph)
65 miles = 40 miles (Charge, 37.8 mpg) + 25 miles (EV, 0 mpg)
(37.8/40) x (40+25) = 61.4 mpg

3. EV Auto mode for 65 miles (with depleted battery) --> ??? mpg
comparable data: 702 miles, 64.1 mpg, avg. 54 mph, #14

see EV Auto strategy:

It would be interesting to compare the mentioned strategies under the same conditions.
Correct me, if I'm wrong.

 

Thanks, Charles. I'd been wondering about the difference between EV in mine & EV in the Prime since it had the added Auto feature.

 

The additional 25 EV miles resulted from the forced charge were not achieved at 66 mph but, as I understand, mostly at city driving.

EV Auto with depleted battery??

 

First, keep in mind that "city" is a term that's very misleading. Some people think of it as slow speed with lots of stoplights. Other people think of it as anything goes suburb travel... not highway. They are labeled the same, yet the two yield very different results. They really should be separate categories, like the rating system in the UK.

Second, the use of the term "highway" is even worse. It spans any speed from 55 to 80, which vary drastically for efficiency results. It also includes hard-accelerations for some people's measure and is only cruising for others. Whether or not you are steady cruising or passing vehicles makes a difference too.

With all that said, my particular test yesterday included the variety of "highway" driving with charge-mode generated EV miles. I took advantage of that electricity elsewhere (scenarios thought of as non-highway) but did still include 2 hard-accelerations onto the highway and some electric-only cruising at high-speed. The goal was to collect data from an ordinary trip... which in my case was extremely realistic, since I was traveling in tandem with 2 other vehicles.

Long story short, this served as an example of diminishing returns. You can indeed squeeze out greater efficiency if you so desire, but there isn't much of a point. Once you achieve 60 MPG fueled by only gas, you can consume the resulting power as you desire. The sizeable gain has already been achieved. The next big step is simply plugging in when you can.

 

if there's no penalty for charging the engine with gasoline, toyota may get a physics award, and come out with a new line of ev's you never need to plug in.
economically, at $2.20/g vs 24 cents per kWh, i would be much better off using charge mode all the time. environmentally, i'm not so sure.

 

Overall, like with the hybrid, that actually did end up to be the case. It boils down to how the generated electricity is used afterward. Used wisely, there can indeed be a gain. Used poorly, there will be a penalty.

That's why different hybrid systems yield different results.

 

Just to have the same initial conditions.
But I agree, regarding to EV Auto functionality is better to start with the recharged battery.

 

I recommend not using cruise control for uphill and downhill areas because ICE will kick in trying to maintain set speed. When it's off cruise control gliding downhill you can see the wheels fully charging the battery with ICE off.

 

just use regular 87, and make sure the gas doesn't sit in the tank longer than 6 months. don't waste your money on higher octane.
i haven't filled up since october 27, 2016, and she's running fine.