EV Auto or HV mode for long drives?

I’ve been switching off EV on longer trips once I’m on the highway and back in when I leave . Seems to be working well for my trips under 100 miles. Yesterday: started trip with 16.2 mile and recharged to 100%. Total lifetime mile 1636 at 222.9 MPG. Finished trip lifetime: 1696 miles at 213 MPG . Total for day: 75.8 miles at 122.4 MPG. Obviously on longer trips the mpg will drop more. I have noticed the car will put itself into EV at higher speeds if conditions are right: favorable temperatures and grades.

 

This morning provided a great sampling of why I haven't bothered. 48°F with several merges on & off the highway, a large hill climb, and a few stops. Putting the system in EV-Auto right away each time did nothing. The engine never started for warm-up or in any of those circumstances.

My guess is EV-Auto simply awaits a draw request of more than 68 kW. In that case, it fires up the engine to provide the extra power. Put another way, you have to drop the pedal to the floor. I didn't today, despite use of the 70 mph highway. So, it was all EV the entire morning.

 

I find EV Auto is much more likely to use the gas engine *if the gas engine is already warmed up*.

During days (especially cold winter days where the engine heat is of extra benefit) where I have 40+ mile drives, I warm up the car (and the engine) 3 miles into my trip when I am on the highway and have just reached highway speeds. by switching from EV to HV. After around 10 miles, I switch to EV Auto -- and the car is much more willing to use the gas engine on uphill sections - even moderately uphill sections of Interstate.

On the same drive as an experiment, I tried twice to go directly from EV mode to EV Auto when I reached highway speeds - and used up almost all of my battery capacity before the engine fired on one of the more significant uphill portions of my drive.

 

Makes sense to me. No hills here worth bothering about. But we're planning a trip to AZ in May, so I need to keep this in mind.

 

Humm, interesting observations. For my drive of 20 miles one way commute (without opportunity to charge at work), I keep my car in HV mode all the way to work in winter morning. Our ambient temp in winter morning is almost always below 14F. In fact this morning temp was 14F. In cold morning ICE comes on regardless, and if I use heat or defroster it ensures ICE stays on. Rather than using ICE just for heat and wasting my EV range in morning commute, I have made a habit of switching my car to HV as soon as I turn on the car in the morning, and come home all the way EV mode. I have never tried using EV Auto, but maybe in the cold morning after ICE warms up and defrost is done, I will try switching to EV Auto to see if that keeps ICE stay warm and use it as necessary.

 

The strategy I use is manual switching the car from EV to HV....

To make sense of what I'm doing any why here's my daily commute. My commute to work is about 18.5 miles. I can't charge at work, not anymore, won't go there .

I drive on a two lane US highway at speeds 55-65 MPH, only a few traffic lights. The commute to work is an elevation loss although there are a few hills to climb either way. Since it is colder in the mornings and the heat pump is a bit of a power hog and other things. Typically what I do is run the ICE most of the way. The warmer it gets (say 50-55 F and up) I switch over to EV earlier in the drive. The way back from work is of course more uphill and because it is warmer the battery just puts you down the road further. So I try to guess how far the range will be that day. If I know it will be 70 F in the afternoon I will typically use more EV in the morning. Getting 200+ MPG round-trip is a good day. Very cold days I may only achieve 110 MPG. I quickly found that using the EV range in the morning and driving home on what remained gave worse fuel economy than just taking control of how the car operated.

So if your commute is predictable, this might be a good strategy. I also do this when I drive down to Atlanta. Same thing applies but slightly different. I will use EV driving over the mountain towards Helen, GA (GA-17 / GA-75), going down I gain back quite a bit and I will off and on use EV at different periods. Typically up hills where the ICE will use a lot of gas. In a 104 mile drive I've come close to 100 MPG average, so this would be the opposite of what EV auto would do.

Going down mountains I don't use charge mode. Looking at ODB II data, it doesn't really do anything to make the battery charge faster and just simply uses more gas when compared to just coasting and braking. That's just my two cents.

 

This video I filmed shows the charge-rate for charge-mode is double that of what you get via the plug...

 

@john1701a Yeah that would make sense over having it plugged in. Just coasting downhill compared to coasting downhill in charge mode there's not any gain in charge rate. Not comparing charge rates between charge mode in level 2 charging... I may not have made that clear in my post.

 

Just pointing out the pack's ability to accept more at times, like during hard/sustained braking.

 

So that seems to me to indicate that limiting the charge rate to 8 amps isn't really accomplishing anything as far as protecting the battery or extending its life.

It also looks to me like using charge mode on the highway and then using up the charge just might use less gas as some have claimed. Rounding things off, you went about 39 miles on a whisker over one gallon. If you got 24 miles out of that EV you generated (80% of 30 miles), that would be about 63 mpg. Even 80% of 25 miles would come to around 59 mpg. I haven't had an opportunity to test this yet myself.

 

The battery pack will take in up to 40kW (for a limited time) when braking, it is reduced when the battery pack is charged or is cold. You can look at the data PID called WIN_CONTROL_POWER (although it might be called something different with different apps).

 

It was 32 this morning and I had to use defrosters. EV would not come on until I turned them off and had gone about 1 mile.

 

Yap, unfortunately defroster ON means ICE ON no matter what days of year it is. I have tried preconditioning car to see if I can avoid using defroster in the morning, but preconditioning had almost no effect on windshield when temp is low in single digit to low teens. BTW, You may want to change your profile so people here knows you are driving a PRIME.

 

Try airing out your car before leaving it. I keep the door open while plugging in. No need to press that MAX defrost button, since any moisture would have already been vented.

 

The car doesn't know where you are going to be driving. If you are running on the highway for a while, then know you will be in a town at slow speed following that, it is best to put the car into HV mode on the highway, let the engine run at it's highest efficiency there, then go back to EV for around town. Save the battery for where it can do the most good.

 

Exactly.

I mean I suppose, if it were possible, to program the computer with GPS data so that it could anticipate both terrain and traffic. Then again, I suppose if they would take it that far perhaps we would have driver-less cars as well...

The way I look at it after looking at too much OBD II data, it is definitely better to let the electric motor accelerate the car in many situations. I live in the mountains so there's a lot of hill climbing and regen. Granted you'll not likely regain the energy used going up a hill by coasting down (unless of course you're going down a much longer, steeper hill than you climbed). As a really broad rule, if you're going under 40 MPH you probably don't need the ICE very often. Mind you, the prime will still do very well as a hybrid...I can't wait for warmer weather the fuel economy just goes bananas lol

 

Odd but I’ve been actually using the cold on purpose to extend the EV and get better MPG. Once I get going in EV, I switch to HV and then switch to EV Auto. It helps with heat and although it uses EV it’s not as much because the ICE is running. It’s kind of like being in hyper HV mode. I’ve notice while the ICE is running, it mostly charges the battery but nearly as much as Charge Mode. All the while it acts like its in EV mode.

EV Auto cycles the ICE on more depending on how much heat is asked for and what the outside temps are. When I drive with my wife she likes it at 76, so I put it in EV Auto which cycles the ICE much more.


Unsupervised!

 

Since November 2017, I drive 100 miles, round trip, 180x per year and the best way to utilize the battery was to figure out the elevation changes along your route and plan to use EV only when you're going downhill or on an even plane. Across 23,000 miles last year, I got 75.9 MPG, with a 52% EV ratio, but, I had to charge my battery around 210 times, which costs me a crapload of electricity.

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