EV Mode not engaging when it should

welcome!
it is a bit of a mystery. the prius control laws are not completely known. the best way to judge the health of your vehicle is by tracking mpg's, not ev miles. it's a hybrid, not a plug in, and designed to keep emissions as low as possible.
all the best!
p.s. don't assume the engine isn't running.

 

EV cuts out at 20 mph, cannot run above that.

 

The car will use the battery in conjunction with the engine and the EV light won't come on. You need an OBD reader to really figure out what is what. As stated above, firmware actions are not intuitive.

 

That assumption does not hold true on prior generations of Prius. The gas engine and battery share the load under certain conditions, so the battery is depleting but the car is not in any true EV-only mode, just an EV-boost mode.

 

Welcome to Prius Chat Heather. Don't worry because the EV light doesn't come on while you're driving, but if you use the buttons on the right hand side of the wheel you can move to display the system of the car showing the road wheels, engine, motor/generator and propulsion battery. This will show what systems are in use while driving and which way the energy is flowing into our out of the battery. It's going to take some time to get accustomed to what the car is doing as you move along, but a heavy right foot will generally demand more from the engine, if you know what I mean. Good advice would be to just drive it like normal and let the car decide for itself what is best for it. It really is very smart for a car!

 

The other replies pretty much covered it.
To phrase it differently: The car is working the way that the TOYOTA ENGINEERS think it should work, not the way YOU think it should work.
That statement was not meant to be nasty or insulting but blunt and truthful.
Worrying about minutiae like this is not good for your health.

 

I stopped looking at the EV LIGHT display soon after taking delivery. It has been discussed a few times that it doesn't reflect what's really happening, and sometimes lags behind what the PRIUS is doing - it's just confusing.

I'd suggest using this display - it gives an up to date display of what's happening. (Your HUD will display the Hybrid System Indicator if you want to see that - it doesn't have the inaccurate EV LIGHT!!!)



That said - PRIUS sometimes will operate the Petrol/Gas Engine at times you don't really understand - I suspect the PRIUS really does know what it's doing - or maybe just a bit confused at the time.

 

the pip always displays the ev sign when the engine isn't running. i wonder if, because toyota has chosen to designate hv miles only when the engine is running in gen 4, they've also changed when the ev light displays.

 

I agree with the other commenters that you need not be concerned by occasional variations in hybrid system behavior, as long as there are no drivability symptoms or other indications of a malfunction.

The conditions during your commute on different days may be similar, but even very small differences in speed, acceleration, HV battery state of charge, temperature (outside, battery, electric motor, or engine), electrical load, or other digitized parameters collected by the hybrid vehicle control system could be enough to tip the scales in favor of using the engine on one day or the electric motor on another.

Details of the control algorithms are, understandably, not published by Toyota, but the New Car Features book does list a few conditions in which the EV drive mode selected with the switch is not available. I believe many of these also apply to EV operation generally:

• The hybrid control system is extremely hot.
• After the vehicle has been parked in an extremely hot environment, driven at high speeds or the vehicle is climbing a slope, etc.
• The hybrid control system is extremely cold.
• After the vehicle has been parked in an extremely cold environment (approximately 0°C or less) for a long period of time.
• The engine is warming up.
• The SOC (State of Charge) of the HV battery is low.
• The HV battery SOC displayed on the hybrid system indicator display is low.
• The vehicle is being driven at a speed higher than the specified value.
• The vehicle speed is approximately 30 km/h or higher.
• The accelerator pedal is being fully depressed or the vehicle is climbing a slope.
• The defroster is on.
• DTCs are stored.

If you’re still worried, you could ask a dealer—or someone else with a Toyota Techstream diagnostic system—to check for diagnostic trouble codes (DTCs) or vehicle control history events, but from your description, it doesn’t sound like there is anything wrong with the car, so I wouldn’t expect such diagnosis to find a defective part or to be covered under the warranty.

 

Do any of you non-UK owners have the energy monitor on the Nav as well ?

 

Not so sure about this, assuming you mean the EV light. I've had my EV light illuminate at speeds of 68 MPH on the freeway under light throttle, of course. The Gen 4 illuminates the EV light at speeds well above the limits we saw in Gen 2 and Gen 3.

To the OP: If you're getting 54-62 MPG, just relax and drive the car...

 

Yep - it's there. I don't have Navigation - an $8800 extra!!! (well, it comes with more than just Nav).

I rarely use the Nav energy monitor, using that screen to monitor my USB/CD player/Radio etc.

I've put it on a couple of times when I've had inquisitive passengers who'd rather watch the electrons, Newtons, kilowatts, newton-furlongs and joules flowing than watch the scenery.

 

I know I am UK , but I find the energy monitor on the Nav screen really hard to work out what is doing what. I think its because its at a weird angle, I would rather have the more traditional top down/older style view.

 

That's why I use this one up on the dashboard display (instead of the Hybrid Monitor which is duplicated in the HUD):

 

Yes, the Energy Monitor will give you a much better indication than the EV light on the Hybrid Monitor - which isn't always accurate. And your Hybrid Monitor sans EV light is in your HUD.

 

Agreed, I switch between this and the HSI, but generally leave it on the HSI even though I have it in the HUD as I prefer the big colourful one

 

I prefer the Hybrid monitor because it has the lines for the accelerator's limits for EV mode. I do not want to press a little harder & trigger the ICE if it is not needed at that time. the limes are usually accurate, but sometimes you can get EV a little higher.

 

Is the gen 4 EV light really inaccurate? My gen 3's EV light has always been 100% accurate to show that the engine is off. The battery may still be doing most of the work even if it's off (like during the warmup cycle), but if the engine is off that light is on for me without fail (verified w/ scangauge)