How does EV button work?

Although I don't have one, I think the right way to think of the EV button is that it biases the computer to use the battery more and the engine less. As the battery goes down, the engine will come on regardless. If you exceed 41MPH (not 35) the engine will come on nonetheless.

Warranty: It's like laws. You don't know there is a test case. It's probably better not to ask and not to tell. One nice thing about the Coastal EV mod is that it does not show like buying an EV button and wiring in the normal way. On the one hand, the EV button is standard on the Prius in some countries. OTOH, not all countries have the same warranty. I think there is a note in here somewhere from someone who had a problem with the battery and Toyota gave them trouble because they had added in an EV button, despite the liklihood that it was irrelavent.

 

Here is a pretty good write up on how the EV mode works.

http://hybrids-plus.com/pdf/EV_Mode_in_PHEVs.pdf

Here is another:

http://www.eaa-phev.org/wiki/Prius_EV_Mode_Button

 

Very nicely, actually.
I installed it the very day after purchasing my Super White Prius Touring/#6. It stays in electric mode up to 34 MPH--unless I accelerate to a point needing more power. The ICE will engage if the battery gets to 'Pink,' regardless, too. You can engage it after the ICE has reached operating temperature and below 34 MPH, or after a stop. It can also be used immediately after starting in the event you merely want to pull the car out of the garage or move it or whatever. Not recommended if it's cold out and you simply want a jump on the fuel mileage.

Given the right suburban driving conditions, P&G and all that, I suppose you could KEEP in in EV endlessly.

I'm sure you'll get a face full of other suggestions. I can't imagine my Prius without it...

 

Only with
1) cartoon physics, or
2) A car that is driven only a few miles before selling it, or
3) some form of plug in conversion.

In the real world, energy to move the car has to come from somewhere, and the battery doesn't hold enough energy to last more than a few miles.

You can extend that a bit by using up some gravitational potential by driving downhill, but only if you don't ever intend to drive back up the hill.

This means you either have to add electricity to the battery directly with a plug in conversion, or you have to use gas in the tank.

 

There has been one case where Toyota voided the warranty due to the installation of an EV button. This one didn't go to court, as Toyota eventually agreed to do a warranty replacement, but only if the owner removed the EV button and agreed to never reinstall it. They may not always be so accommodating.

Tom

 

Here is what mine looks like. Hobbit installed it. Basically I use it as an engine kill switch. If you are not in S4, the engine will continue to run sometimes. It is usefull to kill the engine and essentially extend your warm up time. The EV switch should not be used to get extended EV time. This will just lower your SOC and you will have to charge it later. One thing to remember, all the energy in the battery comes from the gasoline in the tank. Even for the downhill segments, you had to get up the hill in the first place. If you use the EV switch to stop the engine is it useful. If you use it to extend EV time it will probobly hurt your total MPG.

 

Here is one more article to read about warm up stages

http://www.techno-fandom.org/~hobbit/cars/five-stages.txt

 

Coastal's is a circuit board that you connect to a couple of wires and another wire that goes into an empty socket on the same plug (all methods of activating the EV mode goes to that same socket). When you pull the Cruise Control stalk to "Cancel" for over 2 seconds, the EV mode activates (assuming the conditions are right; otherwise it won't). The Cancel still works for the Cruise Control; just pull it for less than 2 seconds.

Yes, if you use the EV mode wrong you can waste gasoline. I use it when I'm in a large parking lot and want to move the Prius a short distance. The actual trip may take about 40 seconds, but the Prius doesn't know that. So the ICE will kick in after 7 seconds or so and stay running for the rest of the short trip. Using the EV prevents the ICE from starting and shouldn't require the ICE to run extra on the trip home.

 

I use it mainly in two situations: 1) to move the car very short distances, such as in my driveway or through a parking lot, and 2) before the car reaches the fully warm S4 phase that Mapman has described, to force an ICE shutoff when the ICE isn't needed for propulsion.

I could try to describe how its indiscriminant use that others are cautioning against wastes gas, but I'll leave that to others who have already written about it. I suggest you do a full search on Priuschat for several threads that discuss it in depth.

 

Some people have an actual button installed on the dashboard. The Coastal Tech EV switch is a tiny little gadget that is installed behind the right-side passenger air vent, and is therefore not visible. It is engaged by holding the cruise-control stalk towards you for about 3 seconds.

What that EV switch does (of any type) is it tells the engine to shut off. The computer will refuse this command if it decides the conditions are not right: If you are accelerating, driving over 34 mph, if the traction battery is too hot or too cold, or if the engine was just started and has not yet warmed up enough, or even for a very brief time after starting an already-warm engine, or, finally, if the SOC of the traction battery is too low.

While in EV mode, the computer will start up the engine if any of the criteria is exceeded. Or you can start it by engaging the EV switch a second time.

IT IS A VERY VERY VERY BAD IDEA TO TRY TO MAXIMIZE THE AMOUNT OF TIME YOU SPEND IN EV MODE. All the energy comes from gas (unless you've performed a $15,000 plug-in conversion). The way to use the EV mode is very sparingly. For moving the car a very short distance, when starting the engine would be wasteful, or for brief periods when ALL of the criteria below are met:

1. The battery SOC is very high; AND
2. Your driving at the moment demands very little power from the car; AND
3. For whatever reason, the car is reluctant to go into electric mode on its own, probably because it's not yet in Stage 4 (full hybrid) operation because it's not warm enough yet, or you have not had a 10-second stop since getting warmed up, or it might be keeping the engine on because you have the heater on.

When all th above are met, you can use EV mode to draw down the charge from the battery.

You might also want to use it for very slow driving, say, in parking lots, or to impress girls.

While there was one case of a warranty issue, as noted above, a number of people have shown their EV button to their dealerships without problems. You are taking a chance. But considering how reliable the car is, I personally consider it a small chance.

I have the Coastal Tech EV switch, from the very first production run. I was the first member of PriusChat to install the Coastal Tech switch, though several people had already installed other implementations.

Here's how I use it most often: When driving on slow-speed residential streets with a lot of stop signs: I use the gas engine to accelerate from a stop, then use EV for the slow, steady-speed drive to the next stop. Then I use the gas engine again to accelerate, and EV for the slow steady speed again, etc.

And since the engine will run for a while every time it's started cold, and will be putting energy into the battery, I try to use EV as I approach home on the last drive of the day so that my SOC is not high when I park.

IT IS VERY INEFFICIENT TO ACCELERATE ON EV.

 

The Australian model comes complete with a factory fitted EV switch. I use mine regularly when visiting my mother in her retirement village. Just keeps the noise down, when leaving late at night. Apart from that, very rarely use it. I can still drive reasonable distances in EV mode, just by being careful with the throttle (and it helps having a number of downhill segments to keep the battery charge up). If the car did not have the switch, I doubt that I would miss it.

 

Yes, that's worth mentioning. While the software for the EV mode is in every Prius the world over, the North American version doesn't have the actual button to activate it.

 

As above.
Also I think the warranty on the HSD system including battery is 5 years and 100,000km not as good as the USA warranty. I'm guessing from this Toyota believe omitting the EV switch makes the battery last longer. To me that is incentive enough to minimise my use of the EV switch.

It's my belief the EV switch shifts the point of power demand that the ICE comes on upwards but you can't accelerate very hard without the ICE coming on well below 34MPH.

Don't sweat over the EV switch, you're not missing out on a magic button, it wont improve your economy.

 

Hiya, the UK version of the prius comes with an EV button, and yes our warranty is less than yours in the US.

The EV button is really only of use when shunting the vehicle around short distances, it avoids starting the engine and so saves wear and tear. I also like to use it when coming home late at night or leaving early in the morning - or when the neighbours are outside !

But it really doesnt make any difference to MPG, and the distance it gives is very restricted - as it is quite hilly round here I certainly can't get more than half a mile before the ICE cuts in automatically. You might get a mile and a half on the flat.

So, its standard on our prius, but if I had to pay to get one I wouldn't bother.

 

Techno one-upsmanship aside, I get a good deal of use from my EV switch and use it daily. It punctuates the E in electric/gas hybrid and, if it sells another Prius when I'm pulling away from the pump, through a parking lot, in a neighborhood, or on a college campus, then I've done my evangelical duty in getting the word out that the next generation of transportation is/has been here.
My son is studying automotive design in mechanical engineering. The car's a good show-and-tell for college students, too.
Nay-sayers and speculators be damned, I love EV mode.

This my Green Egg. My name is Sam. Go, Egg, Go.

 

The nice thing is that, since the software is already there, if you want to have the EV mode, it can be done for next to nothing. All that's required is a way to short one pin to ground. Some have installed their own button while others have converted the "flash to pass" part of the light stalk for activating the EV mode.