What factors affect engagement of EV mode?

There are some very knowledgeable people on here who probably can give you a really good guess but.............only the Toyota Engineers know for sure.

I personally think that trying to out-guess their programming by manually switching to EV mode is just an exercise in futility.....usually.

 

You can’t have much throttle input.
Battery has to be between 4 and 7 bars. So if you have full 8 bars you can’t put it into EV. But with full bars it’s going to use battery only if it can so you don’t need to use EV-button anyway.
Battery temperature also effects it can’t be too cold or too hot.
Also if engine is in warm up you can’t use EV-button.

EV-button is only useful if engine would start but isn’t actually needed to produce power. Some examples would be to drive out or into parking slowly, moving the car for short distance, stopping the engine to run because of heater demand.

 

We've called it stealth mode for so long, the EV mode reference threw me.
You'll find as you read thru posts on the topic that there are 4 warm up stages that relate to stealth mode.
. In short, once your ride is warm, and presuming your traction pack isn't down in the pink zone, you can enter stealth. Wayne has written some good stuff ... and provided several links;
http://drivesmartwi.com/uploads/DSW_Toyota_Prius_Initial_Stages_of_Warm-Up_Wayne_Revised_2_.pdf
Enjoy reading up!
.

 

As far as I can tell, from exhaustive experimentation and internet searching the activation of the EV mode in The Prius is pretty simple.

If it's a Full Harvest Moon, and you are driving in a southernly direction, during El Nino, press the button and EV mode will engage.
Quarter cycles of the moon and/or Paper Moons or directions not copacetic with the obtainment of Cajun Food and you're likely to get the EV mode not available message.

Although more dangerous than texting while driving, (not recommended...avoid this technique) I have found that if I spit in my hands and mutter out loud:
" I wish I could, I wish I might, Put My Prius in EV mode Tonight!" then press the button? At least 75% of the time it will actually engage.
I have no chart or graph available to explain the connection.

A wise man once said, " I don't always drive in EV mode, but when I do, I choose The Toyota Prius".

Let's just leave it at that.

 

As far as I've read, EV mode is/was different in Non-North America market Prius cars.
North America didn't even get the EV button 'till the Gen 3 cars and it functions differently than on the rest of the world's cars.

 

Engine isn’t at warmup immediately after startup. When you just start Prius engine is off. Then it’s spinned with MG1 then fired and then it enters warmup.

 

Hi valde3. The exact nature of the EV logic seems to vary slightly from one market/region to the next. Here in Australia the EV mode (button activated) definitely works all the way from 3 bars up to and including the full 8 bars SOC. I have tested this many times and can say this with 100% certainty.

As the SOC tops out at the maximum (top end of the 8th bar) however, then yes EV mode does get locked out. This does not happen immediately on entering the 8th bar SOC though, it only happens if you continue regenerating for too long after obtaining that 8th bar.

Essentially it inhibits EV mode just before it hits the panic state of "I've got too much charge and will have to dump some". Typically for example, if I'm regenerating at slow speed in EV mode, then it will hit 8 bars and stay in EV for some time, and then it will beep and "kick me out" just seconds before it starts revving the engine to dump energy.

And yes I've checked, it's not just that it will stay in EV mode if it's already there, it will definitely also allow me to enter EV mode with the SOC at 8 green bars

 

And while not perfect, I would suggest that a computer sampling all the inputs hundreds of times a second should be MUCH better than any human being thinking that he can somehow do it better.

 

But there are situations where EV-button clearly safes fuel. Most of them are caused by car not being able to tell the future. One example would be driving into parking spot that has step in front of it. Without EV-button engine is started for 1 second which clearly isn’t efficient.

 

I don't understand that.
I have never observed anything close to that.

 

Maybe you just haven’t driven over one it’s just steep but very short hill. Engine starts because you have to have a lot of throttle to get over it but then you are parked and you can shut the car down.

Another example would be if you start driving downhill from where you are parked. Engine starts and warms itself up through the downhill. Then shuts down and then starts again for uphill. Way more efficient to use EV and let the engine start only when it’s needed.

Another example would be if you are driving in stage-3a so engine is idling but you are not stopping then using EV will stop the engine.

One more example would be if engine is only running because of the heater, but you can’t turn it to MIN because of windows fogging. Then EV will stop the engine but still give enough heat.

 

Way, way, WAY too many things to worry about for me........just to gain a few tenths of a mile in perceived efficiency.

Keep in mind that one way or another 100% of the energy used to propel the car really comes from the gas engine, one way or another.
Unless we are talking about a PiP here of course.

 

Of course we are talking about the normal version. Even though all the power comes from the engine it isn’t beneficial to start it for super short burst. And since it’s more efficient to use engine power directly than to use electric power its best to charge the battery while engine also propels the car.

 

I have found EV mode very effective for driving up onto ramps with the front end to do maintenance work. I affords very good slow speed control. Not sure about the mileage of said exercise, however......

 

As with valde3 and scona, I also find the EV button useful in specific circumstances. Generally I don't think the overuse of the EV button is a good idea, but some of the uses outlined above I totally agree with.

Another one that I often find useful is at a set of traffic lights near me that is just before a large downhill that usually tops out the battery. There is about a 300 to 400 meter flat section of road between one set of lights where I enter the road and the second set of lights where the downhill starts. The traffic moves slow over that section because the lights are synchronised such that the second set of lights is always red when you enter from the side road at the first set as I do.

So I often use EV here and let it run a bit of charge off the battery before I hit the large downhill section. The worst part about not using EV mode here is that I'm often still in hybrid "stage3" at this point, so when the engine starts while accelerating away from the lights (and with the slow traffic speed) the engine can sometimes keep idling all the way down the hill for the next mile or so, which is super annoying.

 

I to find the EV button useful. On leaving home I back out of my parking area in EV then descend a long hill that will take the battery up to all green bars. Near the bottom of the hill I allow the car to reach 31 mph, and that kicks the car out of EV and starts the engine while running along a flat stretch of road.
On returning home, and climbing the hill the battery is always at full green bars. I have a point on the hill where I activate EV mode to end my journey at home as I started using only electric. With some charge removed ready for my next outing down the hill that full charges the battery.
The computers as yet do not have the capability to recognize this routine. In later vehicles who knows with satellite navigation hills up or down could be recognized along with likely energy needed or conserved calculated, and put to better use.

John (Britprius)