Why can't I get into EV Mode?

EV Mode conditions from my reading [must meet all that apply]:

1. * SoC >= 50% [3 bars will work some of the time, in other words, and >=4 bars is always ok]
2. Speed <=34 MPH
3. * 0C(32F) <= Battery temp <=45C(113F)
4. Not accelerating
5. * No defroster use
6. * if in Stage 1b, Soc >=6 bars & ambient temp >=0C/32F

* Credit Ken @Japan with the * items (at least refinement)

Perhaps the ramp slope required too much throttle? Were you touching the throttle?

Post if you figure this out...

 

I can't ever get mine to engage except at startup. And often not even then. out:

 

I'm not sure what the actual battery temp parameters are but, I've noticed that when the car sits at my work for 8 hours or more when the air temperature is below 25F, I don't get to use EV mode. An hour or two in my garage(40F) will usually warm it up enough to allow EV mode. I once got EV to work after having the rest of the family ride in the car for about 15 minutes. I suppose the battery would warm up if I closed the windows and turned on the heat too. I've also noticed that when the temp is that low that even the slightest pressure on the gas pedal will fire up the ICE.

 

Tony, it seems like I've been able to engage EV at temps ~15F or below, as long as the car/battery was warm prior to that. As Evan said though, I hope there isn't a connection. I once had a vehicle with a 4-speed(overdrive) automatic that was designed to not go into 4th if the temp was below a certain level.

 

I've noticed the same thing. I agree that it doesn't seem related to OAT directly. Like Larry, I've been able to engage it after an EBH pre-heat. But at my new townhouse, I can't plug the EBH in. It's been during the colder mornings this winter, probably sub-20F temps, that it's been denying EV. When I first noticed a pattern, I started watching all my temperatures on CAN-View first thing on startup. But then those cold temps promptly disappeared (several weeks ago), and they haven't returned since. Not complaining about that; my last tank and the current one both are in the 64 MPG range. But I would like to learn more about the phenomenon.

 

We observe the battery temperature has to be...
0C(32F) =< battry temp =< 45C(113F)

Ken@Japan

 

Anyway, following is derived from the UK manual.
http://priuschat.com/forums/knowled...ev-mode-european-instructions.html#post163662

It does not say for the battry temerature, but we are sure.
On the Japanese manual, the upper speed limit is 55km/h(34mph) same as EV mod on the NA model.

Ken@Japan

 

i found this link on the forum Prius EV Mode

 

I have used EV mode in bitterly-cold North Dakota winter weather, but only after the car has warmed up sufficiently. Outside temperature is not a direct parameter, but if it's cold outside, the battery will get cold. I had moved away from ND before I got the CAN-View, so I have not seen extremely cold battery temperatures that I could measure, but I've seen it refuse to go into EV mode when the battery is too hot, as Ken says. But the battery warms up pretty quickly even in cold weather, allowing EV use long before the car is warm enough to go into "stealth" mode on its own.

I am convinced now that the parameters for stealth and EV are more complicated than we originally imagined.

I frequently use EV before the car is warm enough to go into "stealth" on its own. In fact, that's one of my principle uses for EV: If the SOC is up around 65% but the car won't go into stealth yet, I'll use EV until it's back down to 60% or so.

To the OP:

If you are not accelerating AT ALL when you try to go into EV, then I'd guess it's a temperature thing. But even the slightest acceleration will often prevent EV. And an uphill ramp is a bad time to use EV anyway, as it will draw down the battery quickly.

 

1b is not in Daniel's stages write-up, but Ken@Japan reports in the related thread (hobbit's archive) that one can engage EV after about 56 seconds of 1a, even if Stage 2 temp not yet reached. The Japan Prius folks refer to this as 1b.

 

Hi ksstathead,
Are you already driving your Prius?
I think you're very good understanding about Prius.

I would like to tell more preciously...
Battery bars >= 4 bars (or 3 bars if the SOC%>=45.0%)

Please add one more...
No defroster use

Ken@Japan

 

You are most kind, Ken, thank you.

I have had a test drive and studied this stuff obsessively. I am developing a 1 page chart for reference to the stages and the related availability of the various operating modes.