ALL EV Modes explained

welcome!

when you turn the car on, if it has any wall charge, it will default to ev mode, and only run ev until the charge is depleted.

if you want the car to mix engine and ev as it deems best, change to ev auto after turning it on.

if you want to preserve your charge for future use, change to hv after starting.

if you have no wall charge, it will start in hv mode.

there are some caveats to all these, and one people experience the different modes in unusual ways.

 

Have you reviewed the information under “Plug-in hybrid system operation mode” and the following sections, pages 79–85 of the Owner’s Manual (15.7 MB PDF)? They even included a state chart, showing the four modes—EV mode, EV auto mode, HV mode, and hybrid battery charge mode—and the transitions between them.

If you’re looking for a more in-depth technical explanation, see the New Car Features book (available by subscription to techinfo.toyota.com); start with the section Engine/Hybrid System: Hybrid/Battery Control: Hybrid Control System: THS-II Control.

There is also an SAE paper with a few more details: Ichikawa, S., Takeuchi, H., Fukuda, S., Kinomura, S. et al., “Development of New Plug-In Hybrid System for Compact-Class Vehicle,” SAE Int. J. Alt. Power. 6(1):2017, doi:10.4271/2017-01-1163.

[Edited to add:] Toyota has a two-minute YouTube video explaining the modes: Toyota How-To: 2017 Prius Prime – EV, HV, EV Auto Drive Modes

 

pleasure.

 

EV mode is default on start up...I don't use EV auto all that much...I manually switch between EV/HV...i usually start in ev mode then switch off to HV mode because of high speed highway that we have to do...given we have a 45 mile one way commute...when in hv i'm saving my ev for slower speed city driving...My commute is EV-HV-EV...and when we return to home we time it to deplete ev as we pull in ...then we recharge...Overall mileage with that routine yields me 80mpg overall....

 

EV Auto is strange, one would think it would be more of a blend between EV and HV, but it isn't, it's EV with the ability to start and use the ICE under heavy acceleration. Apparently I never accelerate fast enough, because it never turns on the ICE and acts exactly like it's in EV.

 

I keep hoping for a software update so that the EV auto will come on at highway speeds or hill climbs!

Posted via the PriusChat mobile app.

 

That's the way I want it to work too.

 

It's bizarre to hear some owners asking for exactly what the previous generation owners complained about.

 

I didn't have a previous gen PHEV to compare it to, just a normal prius. EV-Auto is basically useless to me as is. All I'm thinking about is gas mileage...

 

Thankyou! so i'm not the only one that sees ev auto to be identical to ev mode.

 

They complained because there wasn't any EV only mode, and the limits of the system meant some couldn't avoid the ICE firing up even on very short trips.

The complaints here about the Prime's EV Auto mode is because of the opposite; the thresholds to trigger ICE appear to be so high that having EV Auto seems pointless. For those taking a trip beyond the EV only range, it means they have manually switch to HV mode on highways to preserve range for lower speeds instead of having the car do it, well, automatically.

 

We're not complaining about EV Mode, just EV Auto, I like EV mode, but I have a long commute, so a real EV Auto Mode might make a bit better gas mileage.

Yep, that's what I do manually, switch to HV for the fastest part of my commute, otherwise EV until it runs out.

 

With the PiP, there wasn't a true EV only mode. The EV mode was what you are asking for in the EV Auto on the Prime; just with lower limits on when the ICE turned on because of the smaller battery and no dual motor operation.

I think many had expected EV Auto to be closer to the PiP's EV mode when the Prime had been unveiled.

 

There's absolutely no need for an Ev-auto mode to work as is being described in this thread. I'll tell you why.

For an Ev-auto mode to work the way you all want it to, the car would need to know where you are going now, how fast you plan to drive, the road slope, the traffic situation and (most impossibly) the amount of Ev range you want to preserve for future trips. It could theoretically know some of these, but knowing them all for every trip would be really hard.

The thing is, you might know these things. So, simply watch either the remaining Ev range or the battery percentage and press Hv when your Ev range is down to the level you want to preserve. That's it. Nothing to it, no need for Ev-auto.

Further, the car really isn't inefficient enough at high power in Ev mode to need ICE power for those times you're at higher throttle settings, and that idea (Ev = efficient at low power, ICE = efficient at high power) is the root reason people are asking for this. Doesn't matter. Hv does a magnificent job of balancing Ev and ICE operation already so just use Hv - the same conclusion as the last paragraph.

 

My car knows where I'm going, how fast, stop points, route, it has it all for my commute and the predictive regen -- that data is already being tracked for 99% of my driving.

 

Really? I set a destination for about 1% of my driving.

 

Really, it's part of the predictive regen and a routine daily commute. I don't set a destination, I don't need too, I always follow same roads. The car knows the destination by past habits. (The track I take is in green on the GPS.)

 

It can't know your destination. You could be going somewhere else. Plus, it would have no idea what errands you have to run during lunch or after work and that sort of thing impacts how much Ev range you want to preserve. If it's just a long commute that exceeds your Ev range, don't worry about it, just drive until the Ev depletes. Doesn't matter.