Newbie Question

Yes, it can do that. When the engine kicks on depends on load and the state of the battery. When you get up to about 40 mph the engine has to turn, whether it is running or not, in order to limit the speed of one of the motor/generators. It is quite common to glide along at 25 or so with only the electric running, but not for long distances. The controller will quickly decide that it makes more sense to run the engine than pull power from the battery, and the engine will start.

Tom

 

It also depends on the terrain. If you're going uphill, you're probably going to need the engine. But flats and downhill, not so much.

 

I find for sustaining a steady speed, I can be just over 40 and it will go all-electric for a while. To accelerate though, even at modest school-zone speeds it takes a very steady foot and lots of patience to stay electric. Not recommended unless you are the only car in sight.

 

Perhaps an important question is why you want to know?

If it's just idle curiosity, then the answers given here so far are probably sufficient.

If there is a specific reason you need (or want) to drive with only electric motor for short distances you may want to consider one of the many EV mods discussed at PriusChat.

If you are of the impression that by keeping the vehicle in electric mode you will receive better overall miles per gallon, then the answer you need to understand is that electric mode doesn't accomplish this very well, and in many circumstances can reduce your overall miles per gallon.

 

The Prius is capable of travelling in electric mode up to 42 mph. If you initiate EV mode (electric) via one of the several implementations of the EV switch, then it will only go up to 34 mph in electric.

HOWEVER, in pure electric mode you can accelerate only fairly lightly, and a full battery will only take you about 1.5 miles, and you do not have the ability to tell the car to fully charge its battery in preparation for EV mode. A few blocks is a more typical distance to go in electric mode.

The Prius is not an electric car and was not designed to drive under electric power except for very brief periods under very limited circumstances. It is a hybrid and was designed to achieve very high mileage and very low pollution by using its gas engine and its electric motors together in concert with each other.

There are electric cars. But the Prius is not one of them. Trying to maximize the amount of time you drive electric in a Prius will lower your overall efficiency.

If you want an excellent and reliable gasoline-burning car that is clean and efficient, get a Prius. If you want to be able to drive under electric power, buy an EV. Google ZAP CARS or otherwise research any of the many resources on the web. A good place to start is http://evnut.com.

 

Hi Nick,

The other posters are correct in their comments, but to answer your question, in the phraseology used - The Prius can Go in all electric up to about 68 mph. It will need the engine to get that fast, and it will not be able to maintain that speed in all electric, without following wind, or downhill stretch. But, it can be in electric mode at up to 68 mph, no fuel to the engine, based on my experience, and the transmission simulators out on the Internet. The Prius hybrid system commonly does this slowing down from higher speeds, but not at a rate that triggers the regeneration.

The Prius can function as a pure electric vehicle (with an EV switch installed) up to 34 mph. Above that the engine will kick in for more speed.

For continuous cruising on mostly level roads, then the electric limit is 40 mph. With a maximum state of charge (all Green bars on the State of Charge, SOC, indicator), after accellerating to 40 mph with the engine, then dropping into electric mode, one can cruise on level terrain under pure electric drive for about 2 miles. One can slow slightly, on the down hill swales, then electric power up the other side. But this only lasts until the SOC drops out of the green bars. Then any accelleration will cause the engine to start up. I have one trip I make, where there is a construction zone, and the limit is 45 on level terrain. In that section the battery gets up to just under green bars. Then I exit down a 3/4 mile long downhill ramp. This pushes the battery up in to the either the top green bar, or just below. After a few turns, its onto a level road with no lights for 2 miles, that is 40 mph limit. I cruise that whole length in pure electric, and pull into the light just dropping out of the green bars.

 

<div class='quotetop'>QUOTE(Nick Dearing @ May 24 2007, 04:25 PM) [snapback]449311[/snapback]</div>

Unless you accelerate extremely slow it will 90 % of the time use the ICE. I would say a good example is in parking lots it usually uses electric only. I find that if you use cruise control it will use electric quite frequently even at high speeds and seems more suited to maintain speeds rather then to accelerate only using electric. But like previous posters have said past 42 MPH the ICE spins and adds drag but does not use fuel in higher speed electric only.

 

One other point, Nick, is that the Prius is a low emissions car. To achieve low emissions with the gas engine it must be warm, as must the catalytic converter. The car is a gasoline car, so when you put it in D it anticipates you will use the gas engine, so it runs it, even if it doesn't use the power.

Many mornings, even in summer, I will drive out of my driveway at under 10 MPH using only electric (as shown on the Energy screen) at about 25 MPG. The ICE is running to warm the system, but providing no motive power.

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