How to drive a Prius Plug in

It seems that way to me, but I'm not an engineer and I don't play one on tv, so don't take my word for it. Maybe the experts will weigh in on the subject.

 

I found this to be the case, so I started using the "start timer", and setting it for 2.5 hours before my departure time. The car usually finishes charging 5-10 minutes before I leave, using this strategy. (6:30AM start time, 9AM departure.)

 

definitely not

 

I wonder if I can piggy-back on this thread, perhaps?

I think I'm clear on most things, but perhaps as a double-check for me, do more experienced contributors want to critique this for me?

Most of my miles are done on my daily commute of 2x55-mile journeys. At each end I have c5-6 miles urban, with Motorway in the middle. My EV/HV split of 18/82 over 5K miles pretty much reflects this, I'd say.

For each end of my journey I use EV, with the EV City mode engaged (UK spec, see) and use only seat heater through the journey. My ICE rarely turns on, and when it does it's been due to low ambient temperatures recntly, I think)

For the Motorway leg I allow the car to switch modes on the on ramp, when the ICE starts, and I set cruise at 75, true 70mph. If/when I hit traffic I take a view as to whether to "spend" my remaining charge or save it for urban roads later. Typically I save it in crawling traffic. I do have a couple of questions about this leg, though:

Is there any material difference between leaving the car in EV/HV mode (I always have Eco setting on, BTW) or switching it to Eco alone? I ask for two reasons - firstly when I toggle between them, there does seem to be some sort of reaction from the car, and secondly the horizontal economy display always seems to read higher/worse in EV/HV than it does in pure Eco (or are these just different scales?).

I use cruise as much as I can, but what's the prevailing view on its use on hills - I have a couple of decent-sized ones on my route. Best overall to get them out of the way asap by leaving cruise to do its thing, or click it off and go more slowly?

Welcome everyone's feedback, thanks.

 

If it's crawling in traffic, and the engine is already warm, I leave it in HV and save the EV miles for later, unless I'm on such a short trip that I have enough EV miles to make the entire trip in EV.

 

There's no such thing as EV/HV. It's just either or. What you're calling EV/HV has been called here as EV-boost: what this means is that the ICE runs but the electric motor provides much more assistance using the energy stored in the battery. As an example, on my 15-mile highway commute, driving at 75 mph, I'm seeing roughly 60 mpg. If I was driving in HV, I'd be getting closer to 45.

 

Perhaps I can clarify for my understanding - I can toggle to get Eco alone showing on the display. I can "leave it be" and EV and Eco show.

This latter setting you're calling "Eco Boost" should give me more mpg on the motorway?

What was confusing me was that in this latter setting the horizontal bar eco gauge always seems to indicate that the car is running less efficiently (quicker to go into the power area, out of Eco, for instance). I must admit, toggling between the two settings doesn't seem to make any great difference for me, although I feel an intial reaction from the car. I guess I'll try again and see.

Doesn't this latter setting deplete the battery though, to the detriment of urban running at the end of the journey?

 

The purpose of the EV/HV setting is to let you choose when to use EV. If you have some EV miles, you can choose to turn EV model off (with Eco on) when going up hills or with high speed, you save save the battery for city drive or low speed drive. The EV can use more efficiently in these situations.

 

I get that, I'm trying to understand the nuances better, so I can make intelligent choices on the use of EV. I know I can click out of EV mode at will, to conserve battery.

At the moment it seems like my best option is to just leave it to its own devices once on the Motorway, as only once I drop below an indicated 58 does EV kick in and I start using battery (or so it seems - that's very much the heart of the query).

I'm trying to work out whether my default mode should be just that (Eco-Boost, as explained above), clicking into Eco when needed Alternatively, whether I should go into Eco mode once up to speed on the Motorway ramp, and use EV at the end of my journey.

 

If your goal is to minimize petrol consumption, then I will tell you something you probably don't want to hear: Drive more slowly. If 75 MPH in Britain is the same as 75 MPH here, then your vehicle speed is the greatest contributor to increased fuel consumption, and playing with buttons on the car won't have much affect. The next significant effect comes from accelerating and decelerating slowly. (I feel like a doctor who's telling you to eat more vegetables).

You probably didn't want to hear that. As an experiment, if you make the same drive late at night some time, try setting the cruise control to 48 MPH and look at the difference in MPG.

 

That's the speed (true 70 mph) where my journey time is not too compromised, any slower and I'm spending 3+ hours a day on my commute, which is too long for me - so I'm trying to optimise consumption at that basic speed!

I'm pretty familiar with the necessary driving techniques (I scared my instructor by getting within 1 mpg of him on a measured course ), just looking to understand the piece of technology I'm piloting rather better.

(But I wouldn't look a magic bullet in the mouth, to mix my metaphors!)

 

Okay, let's try again
ECO mode can be chosen in both EV and HV modes. The primary thing it does is adjust the throttle response. So in ECO, depressing the pedal by 1 inch results in less throttle than in "regular".
Now, the EV/HV toggle is orthogonal to this. In EV mode, the primary motive source is the motor+battery. In HV mode, the primary motive source is the engine.
When in EV mode above 64 mph (so-called EV-boost), even though the engine is running, the battery still provides motive power. This is why in EV mode, you can get 115 mpg while cruising at 75 mph. In HV mode, driving at the same speed would net you 45 mpg.
Does that make more sense now?

 

Your patience does you credit sir (maybe rather more than my comprehension does me )!

I must admit though, I'm puzzled why I don't seem to be able to reproduce this effect and see these mpgs in EV mode - are they only available on slight downgrades, where I do max out on my 1-minute consumption display, or should I be able to see them on the flat where (at least currently at these ambient temps) I don't?

If I watch the energy flow display on a flat section, I see energy flowing alternately from and to the battery, changing every few seconds. The battery range doesn't alter during this. Is this what I should expect to see when in this mode?

I fear I'm still missing something - is it back to the FAQs for me?

 

The use of the term "mode" is a bit overloaded, but here are the possible modes:

1. Normal. You see no indication
2. ECO. You see the ECO green icon. This changes the responsiveness of the pedal to be more sluggish and slightly adjusts temp limits for triggering the ICE to come on for heat and A/C
3. Power. You see the PWR icon. This is the opposite of ECO...in that the pedal is remapped to be jumpier.

For each of the above modes you can independently be in EV mode or HV mode. You do this by toggling the EV/HV button; the car will automatically start in EV (if enough battery capacity is available). The car will automatically switch to HV once the battery is low, acceleration is very hard, speed is too high, temp is too low, battery is too full and you are going downhill and a number of other edge cases. Once in HV the car will not go back into EV unless you press the button to request it (and all conditions are met) or you power off and back on.

If you are in HV mode and going fast enough to require it, you will also be in what some have called EV boost. There is no display telling you this. The ICE is running but the car is also using the battery for some power (thus lowering the demand on gas).

Mike

 

In "EV Boost", on the dash display, the car-shaped icon in the middle that normally is solid white with "EV" in it, becomes only an outline.

(Edit) Ooops. What I described is when you are in EV mode and the ICE comes on.

 

Paras 1&2 agree completely (except we have EV City in exchange for Power, which dumbs things down even beyond Eco)

It's EV boost, so-called that's puzzling me. I run in what should be this mode - but my battery doesn't diminish. I switch display and see why (I think) in that power is alternating to and from the battery, cycling quite quickly between the two - i.e. net neutral in energy terms, it appears.

What I'm not getting is why this would be intrinsically more efficient than running the ICE alone - surely there must be power loss in the charging of the battery - it certainly seemed to be the case when I tried a Volt for a few days, for all its bigger battery, once the initial charge had gone, it became notably inefficient. My anecdotal, non-technical and certainly non-scientific observations of economy haven't shown me any discernible difference in economy as yet (EV boost vs ICE).

I warn you, words of one syllable may yet be required before this Brit gets it - your patience is appreciated!

 

Then you are clearly not in that mode. Its purpose is to significantly increase efficiency by using the electricity to heavily assist the engine. When on the highway, I can see MPG average 100 on the one-minute consumption segments.

This video shows it:

Notice the EV symbol is just an outline rather than filled in:

That indicates the engine is running while in EV mode, which what we refer to as EV-BOOST.

 

I think it is established that the PiP is a better hybrid than the Volt. The PiP was designed to be a very efficient hybrid with some additional plug-in range. OTOH, the Volt was designed as an EV with a reasonable range, and then be able to get some extended range with the not-so-efficient, premium-consuming, ICE. Not one better than other; just different objectives.

And note that with EV-Boost, we are not talking about the ICE being used to charge the battery which then powers the electric motor. We are talking about being basically in EV mode with the battery charge having come from the plug, but for some reason (such as going faster than 62MPH), the ICE must be operational. And as has been mentioned, factors which cause the ICE to kick in are often in and of themselves detrimental to efficiency (e.g., speed).

 

The thermodynamic way to think about EV boost...it can be one of two ways to think of it.
First way: you are in EV mode, but going a bit fast so the ICE comes on "lightly," thus extending the distance you can go in EV (at that speed). The second way is that you are running the ICE, which has some efficiency vs RPM graph. You are using the battery/motor to move the RPM of the ICE towards the peak of the graph for the speed you are driving.

I have no idea if the car's computer tries to do this...but certainly once you are past the peak efficiency, any motor/battery use lessens the ICE demand which moves you back near the peak.

Mike

 

That's a really interesting video, thanks.

No - I'm definitely in that setting, doing similar speeds to those shown but don't get that effect?!

I never see 100 averages on the one-minute consumption unless it's a downgrade. OTOH even a slight downgrade does tend to produce it.

What I think is the clincher though is that my battery doesn't diminish in the way shown. In fact, this morning I harvested about 0.6 mile on my journey in.

What's up, I wonder - is it in any way connected to my routine use of cruise, do you suppose? Or perhaps the current low ambient temps here in the UK - at or around freezing since Christmas.