Prius Plug in Gen 4: Switching from EV to HYBRID Mode

[DrPeter]

Hi to all,

When i change from EV to HV mode, i always see a drop in EV miles of about 0.2 to 0.5 miles very quickly despite the engine coming on immediately ( when you'd expect the EV miles to be preserved or even increased).

 

In other words, i thought that once you select HV, the EV miles are ' locked in ' but it always drops slightly and even though the engine does recover some of the drop in EV (about 0.3 miles)....it never gets back to the level i had when i pressed the HV button.

Just asking if this is normal etc...i currently get a full charge of approx. 43 miles despite the lower temps now.

Many thanks in advance, i appreciate any feedback.

Peter.

[TonyHSD]

Hi, 

this is normal and likely because Toyota hybrid system even when engine is running it uses power from the Battery to maintain gear ratios to propel the car. This is the case with all Toyota hybrids. 
For example If the traction Battery is totally dead with no energy at all the car will not be possible to drive. As a result when switching from ev to hev mode the average ev range will drop a bit. 
There is nothing to worry about. 
Enjoy your car. 

[BhxTrev]

Hi Peter,

I’ve never noticed that happening on both the Prius cars I’ve had. I’ll keep my eye on it next time I’m using my car in EV mode probably around town. Just curious as to whether other Prius owners have noticed that happening. 

[AJones]

52 minutes ago, DrPeter said:

When i change from EV to HV mode, i always see a drop in EV miles of about 0.2 to 0.5 miles very quickly despite the engine coming on immediately ( when you'd expect the EV miles to be preserved or even increased).

Do you mean, you push the button to switch from EV to HV and you see the range estimate drop immediately? I don't see that on my Prius PHEV.

What I do see is, if the engine is off and is cold, on switching to HV the engine will normally start immediately but it doesn't seem to be actively powering the car, the engine seems to be on a gentle warming cycle. If you push the accelerator it still sounds and feels like its mostly operating in EV with little or no engine response.

During this period the EV range tends to drop as if it was in EV mode, then after a minute or two once the engine has warmed up, the engine provides much more response and when you push the accelerator you feel the engine responding to demand and over a period of time depending on speed/conditions, the car topping up the Battery to bring the charge level/EV range back to roughly where it was before switching the Hv mode.

I believed this was due to the need to both warm the engine and also to warm up the catalytic converter, which needs to be hot to function effectively and prevent emissions. The Prius uses the Battery in preference to the engine to minimise emissions during the warming period.

If the engine has been running in HV previously on the journey and everything is hot, then on switching from EV to HV mode, the engine starts responding immediately and I don't get that same period of the engine being held back and the same drop in EV range.

That said, even in HV mode, depending on speed and driving conditions, the reported EV range can drop and bounce around by several miles or more. Particularly at lower speeds where the power demand isn't enough to bring in the engine so it will operate on electric motor only for a lot longer, running on the Battery, before finally running the engine to bring the charge level back up once speed/power demand cause the engine to start up.

[DrPeter]

Hi Ajones,

Thanks so much for your excellent reply...i observe everything pretty much as you say; i was just curious about the slight drop in EV miles. It's not a sudden drop...it gradually decreases by about 0.3 to 0.4 of a mile over about 30 to 40 secs. But then it does recoup most of the 'losses' depending on the conditions, like you said.

I think you gave a really good explanation as to what is probably happening...the Prius Brain always knows better than us i guess.

I don't think anything is wrong??...the Battery never suddenly drops at all and always displays the same EV range as was displayed the day before !

I value your opinion and thanks again; i welcome any more of your knowledgable feedback...i appreciate it.

 

Regards,

Peter.

[DrPeter]

Thanks also to TonyHSD...your explanation makes sense... and i look forward to BhxTrev's observations; i think the slight reduction in EV miles is normal, depending on conditions. And the engine does do all it can to recoup that slight reduction. I guess that overall, it is slightly more efficient to use the battery's energy for 30sec or more, whilst the engine is running inefficiently ?

[DrPeter]

30 minutes ago, DrPeter said:

Thanks also to TonyHSD...your explanation makes sense... and i look forward to BhxTrev's observations; i think the slight reduction in EV miles is normal, depending on conditions. And the engine does do all it can to recoup that slight reduction. I guess that overall, it is slightly more efficient to use the battery's energy for 30sec or more, whilst the engine is running inefficiently ?

I think it's correct that the VW Golf GTE does have the function where you can overide the computer and completely retain the EV miles; but the Prius PHEV always does what is best for overall efficiency regarding the EV miles.

I think someone will correct me if i am wrong regarding this issue.

Regards,

Peter.

[AJones]

3 hours ago, DrPeter said:

I don't think anything is wrong??...the battery never suddenly drops at all and always displays the same EV range as was displayed the day before !

No, sounds perfectly normal and your reported EV range of 43 miles is very good, my Prius is several years older and the best I get is an estimated 36 ish miles of range.

Just be aware that as we head into Autumn and temperatures start falling, the reported EV range will start reducing. So don't be surprised if the range drops into the 30s and in the depths of winter, even the 20s depending on the temperature and driving conditions.

[BhxTrev]

Hi Peter,

Sorry but I miss read the title to this thread. My Prius is not a plug in so obviously cannot give you any feedback. It must be my age!

[DrPeter]

16 hours ago, AJones said:

No, sounds perfectly normal and your reported EV range of 43 miles is very good, my Prius is several years older and the best I get is an estimated 36 ish miles of range.

Just be aware that as we head into Autumn and temperatures start falling, the reported EV range will start reducing. So don't be surprised if the range drops into the 30s and in the depths of winter, even the 20s depending on the temperature and driving conditions.

Yea, all good thanks. And yea...i've been through one UK Winter with my new Prius PHEV. I think it went down to about 35/36 mile Range but i do drive slowly.

I've just done a 2mile journey this morning to Morrisons in EV mode...only pressed HV for last 1/4 mile up the hill. The engine came on and the EV range dropped approx 0.6 miles; by the time i parked up, the engine had charged it back up to where it was and then promptly switched off ( EV mode ) 😃

So must be an efficiency reason; it is programmed to use a fraction of a mile of electrical energy from the Battery while the engine is being called upon.