Here and on PriusChat I've seen a lot of people using the EV button to operate the car silently, which is not what I'd like to do with it - I want to use it as an ICE-starve button when I know I don't need the ICE anymore for a while - like rolling downhill a lot - but the Prius hasn't figured that out.

However, I wonder if some of those people and my intended purpose put the Prius at risk. The beginning of every trip for me right now is to roll downhill out of the garage, downhill out of the complex, then wayyyyyy downhill down... the hill that I live on top of.

Normally that means the gas engine comes on and stays on shortly after starting the car running (needlessly?) until I come to a stop, even though I have no use for any accelleration the entire time.

Thinking strictly in terms of gas and accelleration, an EV button would be perfect to avoid kicking it in until I got to the bottom of that hill, ready to leave from a stop light - however, thinking in terms of temperature and all the moving parts in there, would I be putting anything at risk for driving about 3/4 of a mile from a cold start without using a drop of gas?

Note that I'd be driving below 40mph, all downhill, for that entire 3/4 of a mile.

 

When you first push the power button and go into ready, you can push the EV button before the engine starts and you can then EV below 34 MPH. However if your SOC is low or your main battery is too cold or you exceed 34 MPH (even on coasting) EV will not engage or will cancel out.

Wayne

 

This is how I use the EV button when it's warm enough. The first 1.3mi of my morning commute is downhill on 25mph streets with one stop sign and a short rise half way down. I have never seen the battery meter indicate a change in the state of charge so I believe this behavior to be very easy on the system. The only caveat is that I've learned to let the ICE spin up and begin the warming process some distance before I actually need it. (I generally let it idle for the last 1/3 of a mile.) The Prius relies very heavily on the battery while the engine is warming up and is capable of depleting the charge very rapidly during the first 20-30 seconds of operation if your power demand is high enough. Unusually high current draw or forcing the ICE to make power before it's had a chance to circulate oil can't possibly be a good thing.

 

Looks like over on PriusChat this has been mentioned - looks like the transaxle is fine for a mile or 2 on EV mode even without warmup - the initial warmup is really about heating up the Catalytic Converter, not the ICE. However, I'll definitely have to learn to time the warmup mode at that stop light at the bottom so that the car is ready for the highway... this is going to get interesting. And fun.

 

Where do you get the EV button in your Prius? I have the same problem like yours .. I don't need the ICE in the initial part of the run ..

 

I'm about to try it, but it does look anything but trivial. I'm also trying to determine if it worsens your emissions.

Sigma
http://www.sigmaauto.com/jdm/prius/prius0405.php (EV Switch Kit $75).

sited here:
http://web.mac.com/gagix/iWeb/PriusMods/EVButton.html
http://www.evnut.com/prius_ev_mode.htm
http://www.eaa-phev.org/wiki/Prius_EV_Mode_Button

Favorite Install Diagram:

 

Installation options are discussed in this thread:
https://www.greenhybrid.com/discuss/...?t=9956&page=2