EV Button

[HIHOAG]

As a new guy to all this and at the risk of sounding completely stupid.....
What is an EV button?

[htmlspinnr]

I'd suggest that you try searcing the archives if you feel your question sounds stupid :-) Chances are, it's been answered before (this one has).

In short, the EV button forces the Prius into "electric only" mode at low speeds for short distances. In the right circumstances, it could improve your mileage. In the wrong, it makes it worse. It's also useful if you want to move the car a short distance without having the engine turn over when it's least efficent.

[daniel]

Has anyone installed the Costal Tech buttonless EV switch? Was it hard to install? Problems? Comments?

[efusco]

Originally posted by daniel
Has anyone installed the Costal Tech buttonless EV switch? Was it hard to install? Problems? Comments?

If you read my comments on the Cruise Control EV switch you'll see that there are minor problems with weird beeps, inconsistent functioning and occasonal other paroxysmal problems. And, though I haven't personally done the install, I've seen Coastal Dave's circuit first hand and how/where it's installed and it is, indeed VERY simple and fast to perform.

If you desire a fast simple and invisible installation then this is a pretty good way to go. Frankly, if I were going for an invisible install I'd use the headlight flasher technique...must cleaner, fewer errors and, arguably, just as fast to do other than running one wire behind the dash.

[HIHOAG]

I thought the point of the Prius was to not run the ICE if you're just moving the vehicle as short way.

[efusco]

Originally posted by HIHOAG
I thought the point of the Prius was to not run the ICE if you're just moving the vehicle as short way.

I don't think that was, in any way, ever the "Point of the Prius". But, with an EV button, it makes it an option.

The car can not possibly read your mind or predict what you're going to do when you get in and push the Power button. Thus, it gives you 7 seconds of no ICE while it pumps the coolant into the engine and goes through the rest of the startup proceedure. But then it's going to kick in the ICE to immediately begin warming the catalytic converter and preparing for a drive. It does this UNLESS you "Tell it" (via an EV button) that you are not going for a long drive.

I think the "Point of the Prius" is much more complex than making short drives with no ICE.....don't you?

[HIHOAG]

Okay, sorry I over simplified.......I meant the point was to not run the engine when unnecessary. I assumed that moving the car a short distance would not run the engine unless it sensed a higher throttle angle. So, is the EV button something the dealer can install or is it friendly enough that the average backyard mechanic (read ME) can do it?

[efusco]

Originally posted by HIHOAG
Okay, sorry I over simplified.......I meant the point was to not run the engine when unnecessary. I assumed that moving the car a short distance would not run the engine unless it sensed a higher throttle angle. So, is the EV button something the dealer can install or is it friendly enough that the average backyard mechanic (read ME) can do it?

This is not a dealer installed option in the US though it is standard in the EU and Japan. It is simple enough for most people with a little experience with tools and electronics to do. Take a look at my install instructions for yourself to see if it's something you're interested in.

http://priuschat.com/forums/kb.php?mode=article&k=5

[htmlspinnr]

Originally posted by HIHOAG
Okay, sorry I over simplified.......I meant the point was to not run the engine when unnecessary. I assumed that moving the car a short distance would not run the engine unless it sensed a higher throttle angle.

The time when this is most useful is when the engine is cold (below optimal operating temp). The EV button is most useful during these times when you want to move a short distance or delay warmup until a more opportune time presents itself and the engine is still relatively cold.

While the coolant shot helps heat it up, it only heats the head/intake ports, not the entire exhaust system, etc. That, and moving short distances w/ a brief ICE shot basically wastes the shot and most likely leaves you with cold coolant for the next round.

HTH,
-Rick

[daniel]

Okay, here are the situations for which I'd like an EV switch:

1. Winter. My short commute hardly gives the car time to warm up. It does not reach Phase III until I am more than halfway to work. The battery SOC is always nearly full. I would like to engage EV at the point of my return trip that experience will tell me will leave the battery at 4 or 5 bars (rather than full) over night. I will be burning no gas during half my return trip, and the time when the engine is forced to run in the morning will be spent charging the battery. If it's gotta run anyway it might as well do some useful work.

2. I do not know if this is temperature-related because we've had a very late spring and hardly any warm weather yet. But I've noticed that if the weather is cool, the engine is hot, and the SOC is high (6 or 7 bars) the car will usually go rather easily (or all by itself) into electric mode if it's travelling around 35 mph. But at slower speeds, say, around 20 or 25 mph, it is very reluctant to do so. The flow will show that the battery is charging (though it is nearly full) and the mileage will be very low 20 or 30 mpg.

Clearly, this is an inefficient speed for the car. So when I know I'm going to be in this speed range, and the SOC is high, I'd like to force it into EV mode. Then when the SOC is low, there'll be somewhere for that extra power to go.

I will note that in moderately warm weather, on slightly-longer drives, when the car is in phase III and the SOC is moving up and down between around 4 bars to around 7 (rather than staying at 6 or 7 as it does in colder weather) I see MPG numbers at or above EPA estimates after the first 5 minutes. Clearly this car is capable of those EPA numbers. The first 5 minutes drags the average down. That's unavoidable. But I am convinced that, at least in cold weather, I could do better than I'm getting now if I could use more of the battery's range by selecting EV mode when I know the situation is appropriate.