Here in Dallas today it was once again well over 100° with the outside air (shade) temperature of 108° to 110°. On city asphalt streets the outside temperature would indicate 115° or higher at times.

With six charge bars displayed for the traction battery I decided to use EV Mode but EV Mode was Unavailable. I tried four or five more times to use EV Mode, all to no avail, each time EV was Unavailable. After driving a mile or so and still with six charge bars displayed for the traction battery I tried EV Mode once again and it was allowed that time and it worked just fine.

I'm guessing the high ambient outside temperature, along with the traction battery having already been heated up some from just typical stop-n-go driving, that was enough for EV Mode to become unavailable. In normal driving everything performed as usual and I was able to use just the traction battery for extended periods with light throttle, just like usual.

I'm guessing there is likely a certain high-end temperature point in which the EV Mode is unavailable for use. Maybe one for extreme cold temperature too. I'm curious if anyone else has experienced really high outside temperatures preventing the use of EV Mode, yet still have the traction battery perform perfectly normal otherwise.

 

Did you notice a lack of torque filling, the engine kicking in sooner, anything along the lines? Certainly does this in the cold, the battery's max input/output is limited depending on temperature, amongst other things.

 

@Lwerewolf - No, I cannot say I noticed any lack of torque or noticed or felt that the ICE kicked in sooner when driving normally just prior to attempting to use EV Mode, or for that matter soon afterwards when I was using just the traction battery with light throttle pressure. Throughout this time period when I was attempting to use EV Mode I had a minimum of five charge bars displayed and most of the time I had six charge bars displayed, so the traction battery appeared to be fully ready for EV Mode. Everything seemed quite normal in terms of torque when first moving off a complete stop using just the traction battery and when the ICE would kick in...

I'd love to know what the cold and hot temperature threshold is for when normal hybrid results (including inability to use EV Mode) differ from the norm.

 

It's probably more of a gradual decline than a graph. I don't have exact statistics and the programming very likely varies between models.

 

@Lwerewolf - I think this probably explains it!

I found this:

The EV-Drive Mode can not be entered when:

(1) the temperature of the hybrid system is high (ie; the hybrid battery is above 46C),
(2) the temperature of the hybrid system is low (ie; the hybrid battery is below 0C),
(3 )the hybrid battery charge level is low (three bars or less),
(4) the windshield defogger is in use or
(5) the engine coolant temperature is below 0C (maybe 20C on the US Prius)



46°C equals 114.8°F. As I mentioned, the outside temperature as indicated on my car's instrument cluster when I was attempting to use the EV Mode was exactly 115°.

What I do not know is if the EV Mode was Unavailable because the instrument cluster reading displayed 115° and that reading triggered the rejection or if maybe there is a temperature thermistor (unrelated to the instrument cluster's outside temperature digital readout) that triggered the rejection of EV Mode.

Hopefully other hybrid owners here might benefit from this if they experience not being able to enter EV Mode during extreme high temperature weather conditions...

 

I used EV Mode numerous times today with outside temperatures up to 109° and it was always available (with charge level of four bars or more) and worked perfectly.

 

Somewhat related to the ICE turning over when I first start the car after it sitting overnight. I can shut off the engine with 5 or more bars showing, then in the morning in normal Florida temperatures of 80 degrees, the ICE starts whether I have the AC on or not. So the Hybrid battery is not too cold or warm, but yet the ICE will start. Now if I stop at a store and 20 minutes later start the car, the ICE does not kick in. So explain that my hybrid friends. I just took it as the Coolant and/or oil has to be at a certain temperature for the ICE not to kick in. Thanks.

 

@Hues10 - When you make a brief stop and later start the car (when the ICE does not kick in), is your A/C & compressor on Auto mode?

If I make a brief stop with 4-6 bars showing and restart I'm almost sure that my ICE always starts - I presume because I always have the A/C on Auto...

Mine does the same after sitting overnight in the garage (ICE always starts), regardless of showing 5 or more bars when parked or the garage temperature - but I always have the A/C on Auto so maybe that is why the ICE always starts...


I have no clue what the parameters are that sets the conditions for the ICE to start with respect to shutdown time, or to not start with respect to coolant/oil temperature.

I do not know how maintaining the A/C on Auto might affect whether the ICE always starts when starting the car.


No doubt there's a lot of sensors and thermistors all over the car with signals fed to numerous puters...like a NASA SpaceX rocket!

 

@Hues10 - One additional thing I've recently noticed when first starting the car after it sits overnight is that I can definitely hear the ICE start up right away, however there is a short time delay (of maybe 15-20 seconds I think) before the orange moving arrow on the instrument cluster appears that indicates that the ICE is running and is either powering the motor-generator to drive the car or to charge the traction battery. Is this how yours reacts?

 

Ok, do not scream at me. But for some reason, I always shut the AC off before I park the car. As in I shut off the AC part .25 miles before I am at my final destination, let the vent blow to clear the system, then shut off the whole HVAC system before I shut the car off when I am parked. So to answer your question, no the HVAC is not on when I start the car up. Something in my head just says that putting unnecessary strain on a car with all the electronics on at start up is not a good thing. I know, antiquated thinking. But it is the way I roll. Sometimes old dogs actually will not learn new tricks. Is 57 1/2 old now a days? I don’t even know.

 

@Hues10 - Wonderful reply! I accept your reasoning, however for your knowledge Lexus automatically delays unnecessary battery loading at start-up of the A/C when the A/C is on Auto mode. In fact, when I first start the car after it sits overnight in the garage there is about a 1 second delay before the ICE even starts, this is likely because the ICE is needed for the A/C compressor and the A/C delay actually delays the ICE from starting for about a second. (I had stated in a previous post that my ICE starts 'right away' however there is clearly about a one second delay before I hear the ICE crank and run) Give it a try yourself by putting the A/C on Auto mode and see if you detect a slight delay before the ICE cranks up.

Also, there is a short delay before the A/C system's duct blower starts after the A/C starts when the A/C system is in Auto mode.

Lastly, I believe Lexus' A/C system's duct blower is designed to automatically run a short time after the car is turned off to avoid mold/mildew from attaching to the interior of the ductwork and the cabin air filter, which helps prevent bad odors/smells. So, by not allowing the A/C system to automatically perform as it is designed can be detrimental in a lot of ways. The A/C system in the Lexus is very complex yet highly intelligent in that it senses temperature, humidity, light level, smog, etc, and automatically controls the cabin air's condition for excellent comfort for the driver and passengers. I recommend using the A/C on Auto mode.

Nah, heavens no - I don't think 57½ is old. You're just now coming into your own. You've got a lot to learn and a long time remaining to do it!

 

Too kind BC! Agree with the 1 second delay and the delay in the AC air coming out. Can anyone confirm the AC runs a little even after shutting the car off? I haven’t noticed it the few times I forgot to shut the air off. You are probably correct, I need to just let Auto do what Auto mode does. Full disclosure, I even shut off the ventilated/heated seats before I turn the car off. I have a 2013, so not Auto mode (would love to upgrade to that mod), so just habits of mine to turn everything off. Except the ML radio, since I read where people have had the on/off button stick in a pushed in condition. Now I just mute it if I remember. So guess I am a hyprocrite as the stereo probably draws more power than anything else.

 

@Hues10 - Yes, you really do just need to let Auto do what Auto mode does.

With you living in Florida with the high UV and drenching high humidity/dewpoint I can't imagine not leaving the Lexus A/C system on Auto mode.

 

Just to clarify, the Lexus GSh uses an electric compressor. There is high voltage from the batteries that go to a 3 phase inverter, which modulates voltage to control the speed of the A/C motor.

Toyota and Lexus hybrids vehicles can run the A/C compressor when the ICE is completely off (you can witness yourself if you're sitting in traffic/going through a car wash/etc where your batteries have adequate charge, the ICE will remain off yet you'll still get A/C air).

Here is an older PDF that describes how it worked on older Toyota and Lexus models: https://opensiuc.lib.siu.edu/cgi/vie...text=auto_pres

If you're rather watch a YouTube video, this is a lot more recent and covers the topic well:
Hope that helps,

~ im2bz2p345

 

How long after the car is off do you experience this? If it's just a few seconds, then that's likely normal.

If you hear a slight buzzing or humming sounds (that I definitely notice with my car), it's likely the fuel evaporation leak check, described by folks here: https://www.clublexus.com/forums/gs-...e-car-off.html

~ im2bz2p345