EV Mode - Useless

Useless for those disinterested in learning what it's good for, perhaps. Quite useful as an additional tool for those inclined to maximum their fuel economy. EV mode allows considerably more acceleration without kicking in the ICE than you can get in any other mode - more than enough speed and acceleration to have many worthwhile real world applications. I use it nearly daily and while I'm no 'hypermiler', I have no trouble averaging in the high 50's for fuel economy.

 

First, I do understand there are some limited efficient uses for EV.

But while reading this thread and other ones, I still don't understand why so many believe it is better to have the engine run to charge the batteries then use the batteries to move the car (with different losses along the way) rather than having the engine move the car directly...

Blows my mind...

 

I avoid EV in almost all circumstances, except when stuck in a traffic jam or a very low speed and short distance situation. Again, EV mode is a powerful tool but only helpful when used strategically and at the appropriate moment.

In fact, I do not like the EV button at all (never use it, and never will) and if it were up to me I would like to see a fourth button that reads "Suppress EV". I suspect, I would be pressing that one a lot since the frequent dance between EV and recharge via ICE in my suburban commutes annoys me to no end. What a waste.

Let me put it this way: If I cannot average 65+ MPG US on a tank (calculated at the pump) then I am doing something VERY wrong. Using EV often would be one of those wrong things I did.

Cheers;

MSantos

 

I agree the EV button is mostly just a gimmick. As someone else said, 3 buttons are better than 2 in terms of marketing ;-)

As for maintaining speeds above 10mph in EV mode, mine will do that automatically up to 20-30mph in Eco-mode if i'm driving along a relatively flat smooth surface.

You can tell youre driving in all-electric by the high pitched hum of the vehicle and absence of vibrations from the ICE. Also if you switch you display to the vehicle schematc showing the directional arrows for power output that is a good indicator also.

 

There ARE real uses for the increased electric-only acceleration available in EV mode, and if used strategically, it can serve to increase FE. I agree that in many cases, people will be using it wrong and cost themselves more in the end due to efficiency losses in converting energy back and forth between forms. However, there are times, particularly in small towns (and even more so in small, hilly towns) where you aren't trying to go an extended way, but simply get over a little hump of a hill. The downhill on the other side in these situations will regen all the power, so the ICE isn't involved at all and the efficiency losses therefore don't come into play. But I find that in stealth ECO mode, I cannot leave a dead stop and stay sufficiently out of the way of traffic to get over those little humps/hills. But with EV mode, I can run the HSI all the way to the far right without kicking on the ICE, get enough "oomph" to get over the hill, and regen all the power back on the other side. So tell me... how is that less efficient than letting the ICE fire up for 30 seconds to get over the hill and wasting off the kinetic energy on the downhill side with the friction brakes because the battery is still topped up?

Look, let me repeat... for most people, most of the time, ECO mode is far better and EV mode will not improve FE. But for serious drivers, EV mode really does have a place and I really don't think it is fair to reduce it to a "gimmick" (loaded word, btw).

 

I completely agree. I guess my point was that most people don't really understand the physics involved (or worse, think they do when they don't).

 

Absolutely 100% agreed. Most people probably don't understand the physics and I'm sure EV mode is used incorrectly and inefficiently the vast majority of the time it is used. Had the title of the post been "EV Mode - Misunderstood and Misused?", I think we could have had a good discussion about when, where, and how it fits into the overall driving scheme for good economy (although it also has a valid use for keeping fumes out of particular locations, even when it is less efficient). But taking the absolute position that EV mode is "useless", meaning without any valuable use whatsoever, is clearly incorrect and not conducive to starting a productive discussion, imho.

 

I wish there was clear and accurate explanation of the modes (especially EV) from the sales people and in the manual. There isn't much to go on for the average Jane to understand the how, when and where. Thanks for your posts!

 

There was someone on the forum here putting together a document on that subject... now where did I see that post.

For my own use, I really try to simplify things and look at it in terms of as few modes as possible. And the only two that really matter to me are ECO and EV. ECO mode is it for me 99% of the time, with EV used in certain rare circumstances. The basic difference between ECO, Normal (no lights on the dash), and Power modes is just the sensitivity of the first half of the accelerator pedal travel. All three modes have the exact same maximum power if you put your foot to the mat, so you do not lose or gain anything by changing modes - you just change the pedal feel:

• ECO - First half of pedal travel not very sensitive. In other words, little change in acceleration when you flex your foot. This makes the car feel a bit sluggish, since it doesn't seem to be responding to your command. But when you push further, the second half of the travel has all the power. So what this mode does is make it easier to keep a light touch on the pedal. If you accidentally twitch your foot a bit, it doesn't make much change, so you don't blow your fuel economy. You can theoretically get the same fuel economy in the other modes, but you have to have a much lighter touch and better control.

• Normal - Pedal sensitivity is relatively linear throughout the range. As you squeeze the pedal more, more power is applied. This mode does not have the cushion at the beginning that ECO does, so it will feel more responsive to your input. But that increased sensitivity means it will be tougher to maintain that gentle touch that you need for good gas mileage. Not as touchy as power mode though...

• Power - This mode just mirrors the way accelerator pedals are set up in most cars. That is to say that the first little bit of travel of the pedal does most of the change, so that the slightest twitch of your foot makes the car jump to maximum acceleration. This makes the car feel fast, which is why most cars are set up this way. But, the whole rest of the travel of the pedal does very little except stroke your ego, and since the exact same total power is available when you put your foot to the floor in any mode, power mode is really more for impressing your skeptical friends when they test drive than it is for actual use.

It has been said on the forum that the ECO mode also tunes back the AC a bit too, although it seems to still do plenty of cooling as far as I can tell. So I leave it in ECO mode all the time. If I want/need to go fast, I push the pedal a bit further and the car jumps right out. But if I'm absentminded and my foot is not rock stable on the accelerator pedal, the ECO mode 'forgives' my instability and keeps my fuel economy up.

As for EV mode, it has two important uses that I can see:

• Preventing fumes in certain places. Lets face it, it is just impolite to spew exhaust fumes at people. It's almost universally considered rude to blow cigar smoke in someone's face, so now that we have the technology, why not extend that courtesy to carbon monoxide and car exhaust? I use EV mode whenever I'm in a pedestrian area for this reason. Yes, you can go all electric while staying in ECO mode. That is absolutely true, so let me say it before some naysayer jumps in with that. But EV mode allows more all-electric acceleration than the other modes, which you sometimes need (as you are leaving the car park and entering the street, for example), and it also helps ensure that an accidental twitch of the foot won't kick on the ICE.

• EV mode is helpful in certain specific situations where you can think further ahead and know better than the computer about whether or not you need the ICE. Small hills in town are a perfect example of this. In ECO mode, the ICE will kick on whenever the power bar passes the halfway line. That first half is not generally enough to make it from stoplight to stoplight without holding up traffic unacceptably, particularly on a hill. EV mode allows the power bar to go all the way to the right side of the fat part, which gives enough oomph to get over a little hill so you can regenerate the power on the downside of the hill (by coasting) without needing to kick on the ICE.

Most of the time, the computer will do better at managing the decision about ICE usage than the driver, unless the driver is really concentrating on it. So for the vast majority of Prius drivers, the useful application of EV mode is limited to #1. And yes, #1 may well yield inferior fuel economy, but social graces and politeness have their value (however intangible) as well. And for people really focusing on FE, who happen to be driving in a suitable area (particularly slow, hilly areas), #2 comes up often enough to make it worth having a button.

 

Thank you - Might have been john1701a - he has a whole series of papers and articles about the Prius that are very useful - especially to those new to hybrid driving.

 

This is exactly what I was going to say. Today I was coming home and I live on a hill. I have to go past the halfway point on the HSI to go up it -- but in EV mode I was able to get up without issue because I could get over to the right side without the ICE coming on. (I was warmed up)

But really a little more speed would be nice like the JDM cars.

I do live in California where my battery warranty is 10 years / 150k miles. Does EV mode really wear the battery out any more than normal driving? As soon as it hits two bars it's off anyway....

 

This may be a dumb question, but I'm a novice: Does the battery drain any overnight?

If so, wouldn't it make sense to drive the final portion of your last trip of the day in EV mode to take advantage of that charge rather than losing it?

If not, nevermind!

 

Sorry, but I can get it up to it's rated speed of 25 mph except on inclines - with no problem.

I typically use it in the following conditions:

(1) stuck in stop and go on the highway. I can inch along in EV for more than a mile with no problem.

(2) Driving in/out of my development. I live about 3/4 mile into the development, so I can put it into EV mode and go along in the low 20's (speed limit is 25mph in most developments).

 

I use EV mode only for car accidents/excess traffic when the car is basically at a dead stop. Other than that it has no use. EV Mode is like investing in US Treasury Bills. Seems like a good idea at first, but in actually it is pointless.

 

Never mind then.

 

Did you ever get an answer to your question below? I am never able to activate EV Mode when the engine is cold (I.E. Overnight...even when the outside temp is well above 32°F). I always receive the message that EV Mode is Unavailable. I try to activate EV mode as soon as the ready light stops flashing but it does not work.

The only time I seem to be able to active EV Mode is once the ICE is already warmed up. I sure would like to be able to active the EV mode for those times when I am just wanting to drive the car out of the car port to wash it.

 

The HV battery does not quickly self-discharge, so overnight or even several weeks will make little difference in the state of charge (SOC). Because of this, your scenario does not make any sense.

A similar scenario that does make sense is if you live at the top of a very large hill. In this case your battery will gain charge every morning as you coast down hill. You might want to use EV mode in the evening to lower the SOC to take better advantage of this "free" energy in the morning.

Tom