EV Auto or HV mode for long drives?

You guys are totally right, I must have been tired when I wrote this or just was not thinking clearly. LOL.

I was comparing EV Auto to EV mode but in reality was thinking HV to EV mode. Hahaha

 

I’ve only had my Prime 3 weeks. First conclusion is the car is smarter than I and to let it determine the mode. Having owned an ‘06 and ‘10 I’m pretty good at hybrid driving. I was up to 144 mpg before I took a drive which totaled about 70 miles. The car ran in EV for about 20 miles until the charge ran out. Mileage for the trip was 70 something mpg which dropped the average to 121 mpg. With extra cold weather this week I haven’t been able to regain much. I wish there was a trip Mode where we could input the estimated miles so the computer would use the charge more wisely over the length of the trip. Overall I have a big smile!

 

That’s essentially what I do as well, or more broadly, EV at below 50MPH or so, and HV at highway speeds.

 

I routinely make a trip of around 80 miles, 15 of which are city, 10 rural roads and the remaining 55 at freeway speeds which around here means 70 - 75 mph. Using the EV range the car usually makes this trip recording around 80mpg - in moderate temperatures. (Around 65 mpg in winter but that's another story.) I selected EV range in the city and on the rural roads and HV on the freeway as the concept seems logical and making that trip on about 1 gallon of gas - give or take a bit, not driving particularly gently is pretty great. For a while, just for fun I put the car in EV Auto mode at the start which typically ran the battery out after 20 or so miles 13 or 14 if which were at highway speeds. What surprised me is that I generally got somewhat better mileage for the the trips in EV Auto then I could get manually switching modes. Guess the car really is smarter then me. I also experimented a bit with charge mode on freeway return trip thinking more EV for the 7 ish mile final city portion. This did not improve overall mileage. Just observations for a particular type of trip. After two years and 20000+ miles and still having a blast with this car.

 

So basically just drive the car and you get the best mileage?

OP- what was your mileage on the la to sf trip?

I typically drive 100-200 a day but lots of traffic. I am curious what gas mileage I am going to get here in socal. getting the prime very soon

 

I did that the 2 times I hit the interstate since I got my car 1.3 weeks ago but ....
I'm wondering if it is a good idea to EV to the onramp then ask the ICE to hit 65 MPH fairly quickly with no warm up time. Maybe it is better to EV to about a mile from the onramp and switch to HV so the ICE can warm up some before being asked to go all out.

 

The system spins the engine up over 1000rpm before even firing the spark plugs, and will remain in, or make more use of, EV operation if it feels that is best for the engine.
With the exhaust heat recovery system, the gen3 engine warm up time was under a minute, IIRC. The warm ups that take longer are the ones for the emission systems and cabin heating.

 

Great, thanks. I'll keep on EV until the onramp then. Guess it runs kind of like EV Auto; though I put it in HV, it will still be in EV until the engine warms sufficiently. Gotta say, I'm as impressed with the Toyota mechanical and software engineers with the Prime as I was with the Gen II. They do seem to think of most everything to keep things running efficiently and safely for the hardware.

 

@Trollbait is correct. You won't hurt the ICE by starting it at highway speeds. You can watch the mpg indicator and/or the remaining EV range change as the electric motors help the ICE until it gets warm.

But I am starting to wonder if it helps with the economy to warm it up at lower speeds so it has to borrow and repay fewer electrons from the battery. Theoretically that could be a tiny bit more efficient because there would be less current-induced heat loss. But probably not enough to notice.

 

The warm up penalty on the Prius has to do with getting the emission systems to operating temps. While the system 'leans' on the battery more with engine start up at higher speeds, the higher load on the engine at the time means more heat going down the exhaust to the catalytic converter. There probably isn't much one way or the other in terms of which is better.

 

This is true!

 

OK, took my trip to MA today. Started fully charged, EV 6.5 miles to the interstate, then HV 25 miles. Did some errands. I think I had about 40% in the EV "part" of the battery when I headed south though not sure.
I used the "miles/efficiency since the car was started" trip meter, dynamic cruise control.

HV at 55 MPH to a rest area. 91.6 miles, 65.1 MPG. Again HV at 55 MPH to my destination 100.3 miles, 67.5 MPG.
A few city miles in EV Auto to my appointment (all EV) and then to a gas station, again all EV. 9% left on the EV battery when I got on the interstate. Accelerated to 65 MPH, and yes the first 2 miles (and the rest of my EV battery) were all EV so the car did do its "start the ICE gently" thing. HV again, first stop was to pick up Subway for dinner, eat on the road. 73.1 miles 53.0 MPG. Back on the road again HV at 65 MPH (except a few at the 55 speed limit and last 6 surface at mostly 40 MPH), 142.8 miles 53.7 MPG. Combined on trip A (reset after getting gas) 216 miles 53.4 MPG.

Next time (in 6 months) I'll have to reverse the speeds and see how much of the MPG difference is speed and how much is hills, LOTS of hills.

I did notice that once I hit 0% on the EV "part" of the battery, it never added to it even though I had some significant down hills. It's like it has a software separation between the "two" parts. I did hit a flat spot and having found the current MPG display changed the mode to "charge" for a couple of minutes. Total guess based on the bar graph but it looked like I lost about 5 MPG. Ran that way for a few minutes and the EV "part" went to 2%. Thereafter it seemed like that 2% was "added" to the HV "part" of the battery because most of the rest of the way home (~35 miles), it shifted mostly between 1% and 3% but occasionally went to --- then back to 1-3%.

 

The emissions from a cold or warming emission system is massively more and that is why it tries to use battery exclusively during ICE warmup. For that reason I like to switch to HV one minute before I project the need for significant ICE power. It would be great to determine if you can step on the gas during warmup and get the Toyota ICE to change cylinder firing timing and power to wheels, although it would be at the cost of producing LOTS of pollutants. I think if you tell the ICE you need power NOW by flooring the gas pedal, it would give you some or all ICE power.

In my Prius v, I have watched the ICE timing change as the ICE coolent hits early thresholds (60F?, 90F, 130F can’t remember exact numbers). During warmup, I have see x2 - x3 traction battery draws while the ICE is idling and warming up coolent and emission system. I never see that high traction battery draw during normal, post warm up driving. But this is on my Prius v with a much smaller battery. I may have to get a new ScanGaugeII or App for my wife’s Prime to experiment with.

 

The few times I've tried EV Auto the car ran en EV mode (even at expressway speeds) until the EV capacity was depleted then switched to HV mode.
Not sure what difference running in EV mode from the get go would have made.
I would think the car should have done something like:
Run in EV mode at low (non-expressway) speeds and then switch to HV mode when the ICE would be most efficient eg. at expressway speeds.
Doesn't seem to work that way though.
J

 

The OM is pretty vague about EV Auto. As I understand it, EV is pure EV. Floor it and the engine stays off. I tried that and it's pretty impressive especially compared to my PiP. EV/Auto works essentially like the PiP EV. Floor it and the ICE starts. Go too fast and it starts. I have not played with this since I'm so happy to finally have full control (weather permitting) of when the ICE starts. So far, I have seen no advantage to EV/Auto. (head scratching emoticon here)

 

With the PiP, I looked at remaining EV miles in two ways depending on if I was feeling dogmatic or pragmatic.

Dogmatic: Rat's, I wasted gas because I didn't use up all the EV!

Pragmatic: Nice, I have a couple miles of EV left in case I need to move the car a short distance.

With this thing, I run out of EV so rarely so far that I really don't care! At least not yet.

 

I haven't tried it much, but the few observations match yours. I'll have to look into filming an EV-Auto commute, now that it's warming up and heater use won't obscure results.