pulse & glide... accelerate fast or slow?

[efusco]

Originally Posted by nfschlaack

Can I assume correctly that this means exclusively using battery power? AKA Stealth mode?

Nope, you want to avoid using battery power while accelerating both in stealth AND when using the ICE.

[nfschlaack]

Originally Posted by efusco

Nope, you want to avoid using battery power while accelerating both in stealth AND when using the ICE.

OK, now I feel stupid. How exactly do you go in "stealth mode" without using the battery??

[efusco]

Originally Posted by nfschlaack

OK, now I feel stupid. How exactly do you go in "stealth mode" without using the battery??

Well, I probably confused you...my bad.
You can, certainly, go into stealth and use just the battery. The point is that doing so is not very efficient most of the time (other than short runs at low speeds).

[nfschlaack]

Originally Posted by efusco

Well, I probably confused you...my bad.
You can, certainly, go into stealth and use just the battery. The point is that doing so is not very efficient most of the time (other than short runs at low speeds).

OK, I think I gotcha now. Using "stealth mode" to get to P&G is not beneficial as "stealth mode" alone.

[qbee42]

Originally Posted by nfschlaack

OK, I think I gotcha now. Using "stealth mode" to get to P&G is not beneficial as "stealth mode" alone.

Stealth mode is pretty much never beneficial. It's hard to get through your head, but repeat after me: "electric is bad, electric is bad, electric is bad...". Driving in EV mode is mostly good for impressing your friends. It's great fun, and the displayed MPG goes up while you are doing it, but in actuality you are reducing the overall MPG as it is going to cost more fuel to recharge the battery than it would have cost to just use the engine to power the vehicle. There are really only three cases where it makes sense to run in EV mode:

1) Moving a short distance, such as in a parking lot. In this case starting the engine is worse than using the battery. Walking is better.

2) Creeping in traffic. EV mode in this case allows engine starts and stops to be minimized. When the engine does come on, it will run for a bit and recharge the battery, making the restart more worth while.

3) Reducing the battery SOC before a long downhill. Battery capacity is finite, so there is a limit to how much energy you can recapture by regenerative braking. If you know you have a long downhill that will completely charge the battery, it makes sense to use the existing charge in the battery before starting down the hill to make room for the recaptured energy.

Other than these three cases, you are not going to help your mileage by running in EV or stealth mode. You may be confusing it with gliding, which is coasting without power - electric or otherwise. With P & G, you power up to speed (the pulse), and then coast until you slow (the glide). The pulse should be done without tapping the battery, and the glide should avoid using the engine or battery.

Tom

[born2run]

Originally Posted by diamondlarry

You have to be careful with accelerating too hard though. As has been mentioned above, if you accelerate at a rate that requires energy from the battery, it will have an overall bad effect on mpg. I agree with Evan that "dead band" would be ideal but, as Jim says, that is difficult to hit. I generally accelerate up to 10-15 on battery then accelerate from there as gently as possible so as to not have any arrows showing from/out of the battery.

Originally Posted by richard schumacher

It sounds like a paradox but you want to *avoid* using the battery. All energy conversions (kinetic, electrical, chemical) have unavoidable inefficiency, and moving electricity into/out of a battery is especially not so good.

This has been an amazing revelation! I bought my used 2006 3+ weeks ago with 19k miles. I've added ~1,500 miles since then. My first tank got me 53 mpg when I admittedly knew little, if anything, about driving a hybrid. My 3 fillups since then, I have gotten 45 mpg. And that's after spending countless hours on PC reading up on all the cool features and techniques to maximize my [car's] driving pleasure and gas mileage. My weekly driving miles have been virtually identical on all 4 tanks of gas.

I can remember driving with that first tank and, while driving a little slower and slowing down long before getting to the red light line, found that I was driving the Prius very much like a non-hybrid car, except driving slower. Interestingly, these past 2+ weeks, I'm driving even slower and more judiciously watching the MFD to use EV mode more often in accordance with all the good advice on multiple PC boards. About 70% of my daily commute is on the freeway (about 9 miles) using cruise control pegged at 65 mph and the other 30% (about 4 miles) is city driving (each week, I have also had an extra 200 mile or so trip on the freeway). After reading your posts above, it now seems that I probably should run on EV less, run the ICE more, and I may get back up into the 50+ mpg range. Does that sound about right?

[qbee42]

Yes, that is completely correct. Anticipate stops, keep your speed down, and avoid EV mode. That will get you great mileage.

Tom

[hobbit]

As JimboK noted a while back, the sweet spot of engine operation
generally seems to occur when MPG reads between 1 * MPH
and 0.5 * MPH. That's about 1700 - 2400 RPM, all with a
fairly open throttle and high shaft load. This is a coincidence,
the numbers aren't supposed to work out that way by design,
but gives the driver something to shoot for.
.
Ideally, install a tach. Here's how.
.
_H*

[Bob64]

I've noticed that on the scangauge, that "deadband" acceleration is more easily triggered then it seems.

Looking at the amps/hour values coming to/from battery, it seems that at any pedal position, except for the lightest or the hardest, the amperage will usually stick at close to 0 going in or out.

The only time that it really goes into "charge" mode is when I'm trying to trigger "super highway mode" by lifting my foot off the pedal to the borderline between warp stealth and 1300 rpm acceleration, which sometimes seems to trigger the inefficient "charge" at 15amps going into the battery instead of the deadband 0amps/hour going in or out.

If your accelerate at any moderate rate, chances are that your already accelerating at or close to "deadband", even if the mfd shows energy going into the battery.

[Fred_H]

Originally Posted by Fred_H

KISS method: Press the accelerator pedal about halfway down.

Originally Posted by diamondlarry

You have to be careful with accelerating too hard though. As has been mentioned above, if you accelerate at a rate that requires energy from the battery, it will have an overall bad effect on mpg.

I think that there is no risk of accelerating too hard with the accelerator pedal about halfway down.

Is there anyone with advanced instrumentation here who can tell me in what rpm range the ICE runs in with the accelerator pedal pressed about halfway down?

Ken1784 once said that 40% accelerator was considered to be the optimum by Japanese hypermilers. And hey, diamondlarry, now I see you were there too, and said that "Throttle Position Sensor reading of 25 seems to work pretty good for keeping the rpm's below 2200".