When to use EV mode ?

The general answer is "don't" - using EV mode is mostly a mileage killer.

The long answer is that EV mode is good for a small number of special circumstances:

1) Moving a short distance, such as backing out of your garage or changing parking spaces.

2) Holding off the engine when you know a long downhill is coming. In this way you can maximize regenerated energy.

3) Controlling the use of the engine when in stop and go driving. You can see down the road and anticipate the conditions; your car's computer can't.

That's about it.

Tom

Edit: I forgot the most important use - impressing your friends.

 

I use it in the parking lot... that's about it. The car really doesn't like to be in EV mode and I find most of the time it kicks me out, or doesn't allow it unless I push the button right when I start the car or slowing down to go into a parking lot.

I call it 'creeper mode' haha. For the most part the car is smart enough to work things out, I don't even use ECO any more and still get great MPG. PWR to get on the freeway or smoke some jerk on the road

 

Am I correct in my understanding that even in EV mode, the ICE will start after like 30 seconds if the engine is cold?

 

No, the ICE will only start if the battery is low or if you force it to accelerate faster than EV only mode can handle. I say "force", b/c EV mode has a higher threshold for starting the ICE than non-EV mode.

 

In US-market models, it refuses to enter EV mode if the engine coolant is below 68F. Pressing the button triggers an error beep and warning screen, and the ICE starts as normal.

Most non-US models will go down to freezing before refusing EV.

 

I use it to get the car to get the car moved a few feet and avoid gas engine start, say out of the garage and into the driveway, for a wash, if it will. A lot of times it won't, because it's too cold, not enough charge, wrong phase of moon, etcetera.

In those cases you can move the car a few feet if you're really quick (for example, don't hang around trying to get into EV mode, jut go). It seems to give about 20 seconds of EV mode, regardless of conditions.

 

It really depends upon your circumstances. For me, both entrances to my neighborhood include a short hill climb. EV works great for that, since the system is plenty warm at that point and speed doesn't get over 24 mph anyway due to the need to turn again shortly afterward.
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I use EV mode:
1) When leaving the garage - keeps it fume-free. Also, it gives me a quiet exit as I leave for work at oh-dark-thirty. The ICE starts halfway up the driveway when I hit 10 mph.
2) When picking up children at school. This keeps emissions down around the students (with a line full of SUVs, this matters to me). It handles the stop-and go, and it impresses the children .
3) When arriving at most any parking lot, or using a drive-through.

Under many of these circumstances, the car will drop into electric-only mode by itself, but I like being able to control it. I never use EV mode out on the road because the good folks at Prius Chat tell us that this actually makes mileage worse.

 

Parking lots, drive through's and the last six blocks home (very flat) don't fool too much with eco/power settings.......still I don't have much more than three months so it's just playing around. Put in a ScanGauge II a week or so ago so I'm learning.

 

The 3rd gen is really good about tracting on battery at lower speeds when able. Other day I had drove it for an hour or so. It sat for maybe two hours. I went 1.3 miles on battery up to 22 MPH without using EV button.
I don't even bother pushing EV button.

2nd Gen Prius was not nearly as good at tracting on battery at low speeds. ICE was much more likely to kick on when heading out of the store parking lot.

 

So, I think I've maybe been bucking the trend, but I've found once the engine is through it's warm up stage, I can stay in EV up to 25mph. Pretty much every stop sign and stop light, I press the EV and PWR button, which allows me to accelerate relatively quickly up to 25mph without using any gas. Could someone please explain to my why this causes mpg to drop. I feel like I am getting better mpg using this method.

It does add a bit more work, and I switch out of EV mode and back to ECO mode when I hit 24mph so I can keep my display on the screen. Otherwise, the car automatically switched out of EV mode at 25mph but leaves you in PWR mode which drops the mpg pretty quick. It's a game, but using this method, I can make it the last 2 miles to my house getting 99mpg+ the whole way. Seems like that can't hurt the mpg's right?

 

Driving in EV mode is like living off of your credit card. In the short run it feels like you are doing well, because you get all of these great things for free. Eventually, though, you have to pay off the balance, with interest.

In EV mode you burn electricity stored in the battery. That electricity came from burning gas in the engine. The complete cycle goes like this: Burn gas to make mechanical energy, spin the generator to make electricity from the mechanical energy, pass the electricity through the DC to DC converter to get the right voltage for the HV battery, store the electricity in the battery by converting it to chemical energy, convert the chemical energy back into electricity, convert the electricity to the proper voltage by running it through the inverter, and finally convert the electricity into mechanical energy by running it through MG2 (motor-generator 2).

That is a long list of conversions, and each one wastes energy. The conversion steps are the interest on your credit card. They are the cost of storing and reusing energy.

For best mileage, you want to avoid all of these conversion steps. You get that by directly powering the Prius with the engine. If we could always drive at just one speed, a Prius would be a lot more efficient without all of the batteries and electric motors. Unfortunately the real world doesn't allow this, so we have the hybrid system to help with all of the awkward moments of real world driving. The hybrid system helps reduce losses in these situationist -- it does not improve the efficiency compared to driving on the engine in ideal conditions.

In short, you want to use EV when losses would otherwise be greater, such as sitting at a traffic light. But you don't want to force EV when all it does is add additional losses to the system. Your instantaneous mileage will look better, but you will pay for it down the road, with interest.

Tom

 

I wrote something but it disappeared...maybe the browser has played a trick on me....
I use EV mode only on 2 specific occasions:
1) when for any number of reasons I want to delay the warm-up process but I still want to move the car out of a location (e.g. Get the car out of the garage and close its doors)
2) when in a parking lot and want to move the car to another location within it, without starting the warm up process (e.g. When in need to move the car from my office building to where the company's gym is)

For all other cases I simply pay attention to how I accelerate and I get EV mode without the need of the button. This is also why, except for the 2 cases above, the EV button is not particularly useful since the conditions to use it are so limited, that it actually maps normal use of the battery without the need of a button (except when the engine is cold and the battery is charged enough, as mentioned in the 2 cases above).

 

Ah, that explains why I can't use EV when I turn on the car and only want to drive a very short distance. Is there any way to disable that on US models?

 

Ya know, this is not an electric vehicle; it is a hybrid. As several people have pointed out here, if you run the car in EV mode, you are just borrowing from Peter to pay Paul. In most cases, you are actually wasting energy since you will have to recharge the battery with the gas engine.

If you want an electric vehicle, go buy one.

 

Great analogy! That makes complete sense!

I just bought a prius 3 days ago and yesterday I installed a EV mode switch. I think its pretty cool and I wanted to have one. However, of course, I dont want to use it in situations where it will hurt my fuel economy so i have been reading everything I can on the topic.

From what I gather I think I have found a situation in my normal routine that will allow me to use the mode without harming my mpg's...
I live in Ithaca, NY, Yes where Cornell University is... If you know the area you know there are hills everywhere here. To add to that, I live downtown in the valley and work at the top of one of the hills. So I drive through town for about 1.5 miles on flat grade, then go up a steep hill at highway speeds for about 4 miles, then it flattens out for about a half mile before I arrive at work. I figure that I could use EV mode in that flat spot for a half mile as I arrive or depart work. That way my battery is nice and charged when I get there and will be recharged when I go down the hill on my way home.

Is this good use of the EV Mode?

ps yes I know I revived a year old thread.

 

The only way to know if your prosed usage of the EV mode works, is to test it over several days, check/note the fuel consumption each time and then compare it to measurements done over a similar period of time without the usage of EV mode at all. I would do it over a period of at least 1 week, for each mode (with and without).
I would think though that on average the fuel consumption will be the same. The energy you use in EV mode will be compensated by higher fuel consumption in the hilly highway speeds. Please post and let us know, it will be interesting to know how this will turn out.

PS: when I first read that you installed an EV switch on a Prius 3 I thought you meant on a Prius 2010...then I saw in your profile to the left and saw that you have bought a used Prius 2008, trim 3...and the world was "alright" again....

 

Yeah, Like most everyone, I use it to get out of my parking lot, and parking garages. yeah there is an extra conversion step. I just don't like the high idle when i start up. Feels like i can use that high idle to move forward faster, than move backward slowly.