What Happens When ?

[Hybrid-Harry]

On a 2015 Yaris Hybrid, I've often wondered what happens if you select EV mode and drive till the Battery is exhausted.

1. Does the car come to a standstill ?

2. Does it automatically revert to normal mode and start up the ICE and recharge ?

EDIT: Just found out from the User Guide, the ICE starts up.

[CPN]

On a 2015 Yaris Hybrid, I've often wondered what happens if you select EV mode and drive till the battery is exhausted.

The answer to that one is easy as it simply will not let you do that at all! In fact, I've commented elsewhere before that, in my view, the "EV" button is a complete waste of space because even if you press it, if the drive train is in a situation where it needs the ICE to be running, it will simply ignore your button push and beep back at you in protest... Even if you do manage to get the "EV" light to come up (by pressing the "EV" button), yes you can drive VERY gently and get it to stay in EV mode that way but only as long as there is enough charge in the Battery and the driving conditions allow and if, at any time, you ask for more acceleration that would be considered "normal driving" i.e. more power, your request for EV Mode will simply get overridden and the ICE will start up anyway...

It's like GC has said, "this is a petrol powered car with electrical assistance NOT an electric car with a petrol engine to charge it..." (I've paraphrased him slightly)

[johalareewi]

The answer to that one is easy as it simply will not let you do that at all!

Not sure if the 1.5 Yaris drivetrain is the same, but the 1.8 gen3 prius (and similar) will flatten the HV Battery if you run out of petrol.

This is the reason you don't want to do it.

[PeteB]

I wouldn't quite agree it's a waste of space - there are a number of occasions where I find it very useful, some are:

• Moving the car on a drive or car park - not worth ICE starting a warm up process
  
• on a road with humps with someone impatient behind me - can use a bit more acceleration between humps without the ICE firing just in time to shut down again - more peaceful progress and less wasteful
  
• doing a short (½ mile or so journey - e.g. stopping at local cash machine) before then going further - avoids starting warm up process, stopping it part way through, then starting it again (albeit slightly shorter)
  
• in a car park where the ICE will be warming up whilst stopping and starting, I think it's more efficient to let the warm up process start when the car's about to do a continuous run for a mile or two (even in summer)

[CPN]

The answer to that one is easy as it simply will not let you do that at all!

Not sure if the 1.5 Yaris drivetrain is the same, but the 1.8 gen3 prius (and similar) will flatten the HV Battery if you run out of petrol.

This is the reason you don't want to do it.

So, are you saying that in the 1.8 gen3 Prius, if you switch it into EV Mode it will actually stay in EV mode no matter how hard you press the accelerator pedal? If so, that is completely different behaviour to the current Yaris Hybrid (which is also "gen3" apparently) because as soon as you press the accelerator and ask for more power than EV mode alone can provide, the system forces the car to switch out of EV Mode and the ICE will start up...

[CPN]

I wouldn't quite agree it's a waste of space - there are a number of occasions where I find it very useful, some are:

• Moving the car on a drive or car park - not worth ICE starting a warm up process

• on a road with humps with someone impatient behind me - can use a bit more acceleration between humps without the ICE firing just in time to shut down again - more peaceful progress and less wasteful

• doing a short (½ mile or so journey - e.g. stopping at local cash machine) before then going further - avoids starting warm up process, stopping it part way through, then starting it again (albeit slightly shorter)

• in a car park where the ICE will be warming up whilst stopping and started, I think it's more efficient to let the warm up process start when the car's about to do a continuous run for a mile or two (even in summer)

You seem to be saying that you can prevent the warm up process from starting by selecting EV Mode? (even if the ICE coolant is at a temperature less than 40°C) If so, mine has NEVER behaved like that!

[PeteB]

When you first switch on a Toyota (or Lexus) Hybrid, the ICE doesn't start for about 7 seconds. If you press EV during this time, provided the Battery temperature is suitable (it usually is) and there's enough charge (at least 4 bars, sometimes 3 is enough) it will go into EV mode until:

• you deselect it
• charge gets low (usually when it goes to 2 bars)
• you accelerate too hard (more than the middle mark on the ECO part of the ECO gauge - another reason the HUD in the Prius is so useful)
• the car decides to for some other reason

BTW - if you whack the accelerator hard enough during the 7 seconds, the ICE will start early. Gen 1 Prius didn't do this, and it didn't have an EV button.

[CPN]

Ok, I knew all that and that's ok as long as you can be gentle with your right foot. In my case, I'm in a small cul-de-sac which comes out onto a main road that the locals treat like a race track (!) and whilst I can usually hold on to EV Mode after starting until I get to the main road, I'm afraid that EV Mode on its own does not give brisk enough acceleration for me to safely exit the cul-de-sac and negotiate joining any traffic, in a safe manner, that may be there... Even though I may not reach 30 mph in the process, I still need to get up to speed in a timely manner which usually results in the ICE taking over... (especially if the engine coolant is at a low temp)

[Lesolee]

Ok, I knew all that and that's ok as long as you can be gentle with your right foot. In my case, I'm in a small cul-de-sac which comes out onto a main road that the locals treat like a race track (!) and whilst I can usually hold on to EV Mode after starting until I get to the main road, I'm afraid that EV Mode on its own does not give brisk enough acceleration for me to safely exit the cul-de-sac and negotiate joining any traffic, in a safe manner, that may be there... Even though I may not reach 30 mph in the process, I still need to get up to speed in a timely manner which usually results in the ICE taking over... (especially if the engine coolant is at a low temp)

Yes, but the point is you can be sitting at the junction not running the ICE, which is important on short journeys. I run down a shallow hill to traffic lights so I keep it in EV mode all the way. I want it to warm up the ICE only when moving. Sadly there is another set of lights a bit further up the main road, so if a pedestrian crosses I get stopped with the engine warming up, stationary. =MPG fail. It is only 3.5 miles to work so the idling makes a big difference to the mpg.

[CPN]

I know the feeling :(

Most of mine are short journeys currently also... :'(

[MEP's Yaris GS]

I love the way mine will do 15 miles in EV :D

[Hybrid-Harry]

I love the way mine will do 15 miles in EV :D

Smart A**se

[kithmo]

I love the way mine will do 15 miles in EV :D

Mine will........................................................... if I can find a 15 mile long straight downhill stretch with no traffic and a strong tailwind

[johalareewi]

if I can find a 15 mile long straight downhill stretch

That would be GV mode.

[Lesolee]

All joking aside, I did a nice little run to Watlington (about 15 miles away) on Sunday. Although the trip there was a pretty unimpressive 62mpg, the return journey was an impressive 92mpg. I wouldn’t have said the terrain was especially slopey, apart from the last bit up to Watlington Hill, but the mpg is a good indicator that there is a significant slope involved overall.

I get the same thing at lunch times where the 6 mile trip there is around 55mpg but I can often get 99mpg on the return journey. (The average is not especially high, but every time I achieve 99mpg over that trip it seems like a small victory )

[YarisHybrid2016]

From the comments here, it seems EV mode is only really good in start/stop traffic in town? I guess it is probably most useful then as well.

Regarding warm-up - does it limit RPM during this period? I drive in areas where less than a minute after start-up I'm out on dual-carriage/motorway way at 70 MPH... how does the ICE handle this?

(I'm a visit away from placing an order and just curious).

[johalareewi]

From the comments here, it seems EV mode is only really good in start/stop traffic in town?

EV mode is only really any good for moving the car a short distance like a few feet along the drive.

Regarding warm-up - does it limit RPM during this period?

There is a lower limit for ICE RPMs (at all times) but I am not aware of any special upper limits during warm up.

[MEP's Yaris GS]

There is a lower limit for ICE RPMs (at all times) but I am not aware of any special upper limits during warm up.

During warm up if it can the car will use the traction Battery only and leave the ICE on a fast idle (which will still be generating power in itself) but not a direct drive (if this makes sense).

I assume its to reduce engine wear as most engine wear is caused by a cold engine being under load normally.

[PeteB]

actually I think it's because the engine is run with the timing heavily adjusted (can never remember if it's advanced or retarded) as this makes a lot more heat but is inefficient in terms of generating motive power. A healthy stab on the accelerator will snap it out of it and bring the ICE into play.

The idea, I believe, is to get the engine, catalytic converters etc warmed up as quickly as possible for fuel and emission efficiency.

A guru from Toyota Head Office once told me (for the Gen 1 - may not be true now) that letting the engine do it's warm up thing whilst stationary and only driving off after the ICE shutdown would be repaid by better fuel consumption if the journey was more than a few miles.

[Lesolee]

From the comments here, it seems EV mode is only really good in start/stop traffic in town? I guess it is probably most useful then as well.

EV mode is where you press the switch and try to keep under traction Battery power for as long as possible. Confusingly there is also an EV light which shows you are running on Battery power only. You don't need to explicitly press the EV mode button in traffic. The car will switch on the EV light (but not the EV mode light) automatically in stop/start traffic. The car will do the work for you so just don't worry about it.

I use the EV mode switch at switch on to get out of the garage and off the drive without starting the ICE. After that it sorts itself out once it has warmed up. I do encourarge the EV light to come on by deliberately easing off the accelerator until the EV light comes on. On level ground it will do this up to about 42mph. Driving on level ground below 40mph using the ICE is not very efficient, but hard to quantify. I have seen below 50mpg instantaneous mpg readout on level ground when the ICE is running. I think you get better mpg at 50mph on level ground (compared to 40mph or less) if the ICE is running (this is for an Auris). My thought is that the ICE is efficient when it is producing a certain minimum amount of power. The power required to run on level ground at 40mph or less is not enough to make the ICE efficient.

As for running the engine up to 70mph within 1 minute of starting, of course it will do it. I wouldn't think it was especially good for the engine though, but we are talking long term wear here. In this case I would not start in EV mode. Let it warm itself up a bit before hitting the motorway. On the other hand, these cars use SAE 0W-30 oil which is really thin, and designed for stop start running. Maybe running the engine hard after 1 minute will cut down the engine's life from 300,000 miles to 200,000 miles. I wouldn't stress over it!

[YarisHybrid2016]

Good point on the longer-term life of the engine.

The 70 MPH motorway run after start isn't a regular occurrence, but neither is this a regular vehicle (the ICE being totally automated), so was curious as to how it would handle this situation. I wondered if it might limit RPM, and thus performance for a few minutes so you didn't push the engine hard whilst it was cold.

If it has a warm-up period it has to complete, then I have no problems doing that if that is what it needs.