EV cannot turn on at 100F

no... i live in arizona. 110+ degrees every day, and i can use EV just fine. There are many reasons why EV would not be available. The ICE probably needed to complete the warm up cycle first.

 

do you turn on the a/c in the car? if its too hot in the car, and the hybrid battery can't cool down, then yes, the EV mode will be disabled. Does the EV mode work at other times?

 

I had the same issue a few weeks back but it wasn't quite 100F. Thought it would have needed a trip to the dealer but then it went back to normal the next day. Couldn't quite figure it out.

 

I'm guessing your hybrid battery was > 115F from your previous driving. This was copied from my post in the gen3 warming up stages thread:

EV mode conditions:
Engine coolant at or above 0C/32F (20C/68F on US models?)
Windshield defogger not in use
Hybrid system (HV battery) in the range 0C/32F to 46C/115F (no x-gauge yet?)
HV battery state of charge (SoC) at or above 4 bars
Speed below the applicable limit (10 or 25 mph)
Not in S1a or S1b

EV mode terminating conditions
Failure to meet initial conditions (do limits differ?)
Excessive power demand

EV maximum speed by stage:
S0 and S2: 10 mph
S3 and S4: 25 mph (10 mph if engine coolant below 70C/158F)

 

I would like to add that I also find that the EV has a mind of it's own. One day goes on the next no.
Very sensitive
I presume it is all to protect the system.

 

I was camping and one of the days was 104F and the EV would not activate. It was also extremely difficult to stealth for more than a few seconds without the gas motor kicking in.

 

EV is finicky, but one of the factors is SOC. There are not many instances where it is more economical to use that power for motive force instead of ac when its this hot out.

 

^^ Yeah my SOC was 6 bars so all the parameters were satisfied other than probably the temp of the HV battery being below 115F which was why I wasn't able to engage stealth or EV

 

This has been discussed in http://priuschat.com/forums/gen-iii-2010-prius-technical-discussion/67855-electric-vehicle-mode.html
Post #55 is me, back in april, asking about EV mode not working as expected (dozens of times before). fully warmed up, not overheated, soc high, EV wont engage, even first thing next morning.
Since then, i rarely try to force EV mode anymore. But I have increased my mpg from about 49 to about 64mpg just by following the tips at http://priuschat.com/forums/gen-iii...ink-im-getting-hang-60-mpg-4.html#post1145624 for the past 1.5 tanks. Simply amazing that I can get better mileage than a buddy's Harley.

Never stop learning.
rich

 

I thought it was 15mph for the slow speed EV mode? Perhaps not....

I'll see if I can find the XGAUGE for battery temp. That would be cool to see....

I do know I cannot use EV mode if I haven't driven the car for 24 hours of more until it finishes the initial warm up. If I've parked for several hours, I can turn on the car, put it into drive and hit EV to delay initial warm up.

I wish this wasn't the case as sometimes I just need to move the car out of my parking spot to get my motorcycle out and wish I could avoid using the ICE at all .... since I shut the car off like 30 seconds later.........

 

I added battery temperature to my spreadsheet ...

The problem is the math ... I am unsure about it.

4D 7E = 27.4C
4E E3 = 28.8C
4D 40 = 27.2C

Sadly this reading is not in the normal "-40 based C" like most of the other temp readings in the car... I need more samples.... but right now if you try it, it just takes the first byte and subtracts 50 which gives you 27C or 28C. I doubt this is right ....

 

I just did some testing and the math seems to work the way I have it now. (For both F and C.) It may be slightly inaccurate so don't take the reading as gospel -- but you should have a general idea. Seems my battery started at ambient when I started driving and ended up at 83F or so at the end. Not bad really....