Question about comment in PRIUS Manual

welcome and congrats! driving in ev mode uses electricity. the engine has to use gasoline to recharge the battery which is less efficient than using the gas to drive the wheels. the computer knows when to use the battery most efficiently. if you drain it down, you defeating that process. there are a couple of nuances such as if you know you're coming to a long downhill that would refill the battery, it makes sense to intentionally use it up before reaching that area. and of course, using it to move around your driveway, a parking lot, etc., is no big deal. all the best!

 

You should feel free to use the EV switch to move your car, such a short distance and slow speed you don't want to warm up the engine.
(Parked in handicapped parking and told to move to regular parking? EV mode. Need to move the Prius to get the Harley out of the garage? EV mode) All your car's energy comes from gas. (The Prius PHV is a different calculation, it gets energy from a plug) The best way to use that energy is to power the wheels with gas, that is the fewest conversions.

Running the gas engine just to make AC electricity to convert to DC electricity to put in a battery to convert atoms to ions, then converting ions to atoms to release DC electricity to invert into AC electricity to turn a motor is a lot of extra steps. So EV mode is not often a good choice to impose on the software. When, in the course of normal driving, the software decides that electric operation is less wasteful than gas operation, (low speed is one such time) it will use EV on its own.

Outthinking the software is very hard, you really have to know quite a lot to make better decisions. In Bisco's long downhill example above, you know terrain that the software can't guess, so you can know to deliberately drain the battery knowing that you will descend over 600 feet soon.

 

I agree with the comments above, saying to just use EV for moving the car, etcetera, that's all it's really for.

Also, anytime I've pushed the EV button, odds are 50/50 (at best!) that it's going to shut me out, say EV's not available right now, would I like to leave a message, and so on.

 

to your second question, you are either in eco, normal or power mode. i suspect no lite is normal.

 

Short answer, this is still a gasoline powered car, not a real electric car.
Longer answers, see previous posters.

It is in Normal mode, the same mode used for the EPA and CAFE tests.
ECO and PWR are called by green mode indicators, but Normal is not.

 

I am assuming when you say EV mode you mean "pushing the EV button" mode. As noted above, there aren't a lot of times where it makes sense. However, using the EV mode to achieve a glide is a very different story. This is when the EV light next to the ECO light on the system indicator comes on. This means the engine is off and you are running on the battery/MG. Most of the comments above concerning the cost of the energy in the battery are incorrect. It is the least expensive energy in the car. For urban-stop-and-go driving, the energy comes from the regeneration system and is essentially free. Even at higher speeds, the Synergy firmware will only use the engine to charge the battery when there is excess energy available. Using the battery to extend your glide, while getting 1500+mpg, is how you get to 700 mile tanks.

 

Beware that it is very easy and common to newcomers who try to do better than the car can do itself, to instead outsmart themselves and reduce actual MPG. Excessive use of EV is one of the paths to this defeat. Drive 'naturally' for a few tanks to establish a baseline. Then later when trying to do better, this baseline will serve as a gauge to help show what works, and what doesn't.

While the energy recovered by the regeneration system in stop-and-go driving is sort of 'free', it isn't the best possible value if the 'stop' portion can be reduced or avoided through more intelligent speed control. Every time energy is converted between speed and battery, some is lost. Speeding up to a stop will put more regeneration into the battery, but gliding up with less braking at the end is even more efficient. And gliding from far enough back to let the light turn green as you arrive, avoiding any braking at all, is better still.

(Note: gliding all the way down to 0 mph for a stop sign isn't the most efficient, because there is some required overhead power just to keep the ignition and computers running. Because of this, 'most efficient' steady speed for current generation Prii is somewhere in the vicinity of 15 mph, not walking pace. Gliding into a stop sign much slower than this gains nothing, though the actual threshold minimum speed for this has not been determined here. But this minimum doesn't apply to stop lights, where you can't go as soon as you stop, but must wait for the green light.)

 

fuzzy1 is exactly correct in that you need to drive the car and see what works for you. Do not impede traffic and always be safe. My commute is probably very different than yours and my techniques may or may not be appropriate for you.

 

I was told there isn't a HUGE difference between ECO mode and no mode selected, but ECO mode does make the "system" try and work in the most power/fuel conserving way possible where it's a bit more liberal with no mode selected.

This is similar in how PWR mode doesn't suck up fuel, but rather it gears the system for more "performance minded" handling while driving.

 

The primary difference is strictly a user interface 'touch-and-feel' thing in mapping ( interpreting) the gas pedal position. ECO makes the first half of the pedal travel less sensitive, to allow us clumsy folks more precise control of engine power. PWR does the opposite, making that half more sensitive, so the engine reaches its high power with less pedal travel, making the car 'feel' more responsive. This is the same touch-and-feel adjustment built into many traditional cars to make them feel powerful, even if they really are not.

But the differences are made up in the last portion of the pedal travel, so all three modes converge when the pedal is floored.

Because this is done simply by mapping the gas pedal, the ICE and 'gearing' don't need to know what mode is selected, they still behave the same.

There are some other, lesser differences involving climate control power, cruise control aggressiveness, and engine coolant temperature thresholds for allowing the ICE to shut off.

The MPG differences between ECO, Normal, and PWR should be small, and depend on the driver style. Most typical drivers should do a bit better with ECO, but some do better with Normal, and a few even do best in PWR. Numerous drivers don't like the feel of ECO, as if it makes the car wimpy or gutless. Some prefer PWR because it makes the car feel more similar to their past cars with spirited throttle response.

Use whatever mode you prefer. If ECO doesn't fit your style, you don't have to feel guilty about being wasteful because it doesn't really make that much difference.

I leave my car in ECO full time.

 

Notice that at full throttle, all three modes are the same, there is not more (or less) actual HP available.

 

I use Normal all the time now, after using ECO for the first few months. I got frustrated with the pedal travel in ECO.

I do wish some of the peripheral effects of ECO could be retained in Normal. Wish list?

 

Offhand, I think ECO just kicks the speed of the HVAC fan back.

 

When in ECO mode, the ECU also tries to economize A/C operation.

 

You are only partially correct here. Anytime the SOC dips under 50% or so, energy will be forcefully taken from ICE to bring the SOC higher. Considering that the typical SOC is only 60% or so, not enough of the "free" energy to play with.

 

This may be the case during highway driving, but not in urban/suburban situations. I regularly drive with 2-3 bars and the engine stays off. It is not energetically efficient to keep the battery full when you can use pulse-and-glide in stop-and-go traffic. The battery will be charged by the regeneration systems and a bit during the pulses if the Synergy system sees excess capacity in the engine. You can use the battery to extend the glide as necessary. I do not use the battery to accelerate.

 

Not discussed in the manual, there are is a threshold speed, 42 mph, that separates the hybrid-mode, from high-speed driving. After warm-up, typically 5 minutes, at speeds under 42 mph, the car will automatically cycle the engine off whenever it can. It will sustain speed on electric power as available . . . just drive.

Above 42 mph, the Prius will 'offload' the engine when possible to reduce the fuel needed BUT there are limits. In practice, high-speed Prius driving will have similar fuel efficiency to a diesel which leads to bizzare behavior by diesel advocates. At speeds under 42 mph, the Prius 'engine off' trick makes it substantially more efficient than a diesel which diesel advocates ignore. They also treat a highway mileage difference of ~1% as significant while ignoring the 10% higher cost of diesel. Strange behavior indeed.

There is no requirement to drive in a special way. However, I've had some success shifting into "N" to glide when possible. Unlike a traditional automatic or manual transmission, the Prius transmission is electronic. It does not shift gears and has no clutch. So you can toss the shifter into any position at any speed and it will not damage the car. This can be a great trick to play on a traditional car guys . . . shift into "R" at high speeds.

GOOD LUCK and welcome to the club!
Bob Wilson