Step on it! Have some fun.

There is a misconception in various posts lately regarding rapid acceleration in EV mode. The commonly held belief that it significantly reduces your EV range is incorrect. Feel free to step on it, and accelerate to your heart's content. Your range will not be significantly reduced, and could, in fact, end up being greater than using a technique of very slow acceleration. Here's why:

• Electric motors experience very little change in efficiency as torque increases from roughly 25% to near maximum, in fact most maximize efficiency near 50%. I could not find any specific information about the Prius motor/generators (gurus please chime in if you have any), but note the flat efficiency curves on these two examples of vehicle motors:

Note the inefficiency below roughly 25% - a range one might consider avoiding if one wishes to get the most power out of each amp supplied by the battery.

• What about the falloff of amp-hours at higher discharge rates? Don't worry about it. It is not a factor with Lithium Ion batteries. That concern died with the use of Lead-Acid batteries to power EVs, shown as "AGM" in this chart:

I live in a community of 35,000, with 10,000 registered electric vehicles (that's right - 1 for every 3.5 residents), and a legacy of using them on a daily basis to get around town for the past 53 years. I am immersed in an EV culture. Part of that culture has been to avoid extremely slow acceleration in order to maximize range, so this is not a new idea - just one that needs to make its way from the cart paths to the streets.

Of course your range will suffer at high speeds, but is affected very little by how quickly you accelerate to get there. Step on it, and go have some fun.

thanks! i have been wondering about this for awhile. i would love to see this for the pip. i would also like to know at what cruising speed the pip is most efficient at, if any.

Good to know! Thanks!

it does use more juice tho, the question is how much? i tested it early on during my commute. 14.8 miles that i usually do with a couple miles left when i get home. when i goosed it, i ran out of juice about a half mile from home.

Not an expert but based on my 4500m so far it uses much more energy the more pedal applied, not unlike using more at higher speeds vs low speeds.

I think same is true for Prius III EV Mode. Using it at stops seems to give a good mpg boost. It allows OK acceleration in pure EV mode, better than ECO mode. It will let you go into the red zone on the power bar but if you push it to much for a brisk acceleration, it will kick the engine on. Be nice if they let the driver give it more power in EV mode.

it prolly does use a lot more juice, but it is exhilarating and as far as fun value goes its through the roof when at the end of the trip you see that 9999mpg knowing you were using/driving in pwr mode

This is great if it is true. I dont know though. Range definitely seems to deplete quicker the more "aggressive" I drive.

As terrain and winds affect speed, I would be more interested in learning what the most efficient power level would be, and how we mere mortals might be able to discern such from the HSI in EV mode. While the efficiency curve is nearly flat, it is not completely flat. There is a peak efficiency power point, but without a graph of the PiP's actual efficiency curve, and some information from Toyota (or one of our well-connected gurus) as to how this peak correlates with our HSI display, we are flying blind.

Making a newb's sucker assumption of 1 for 1 correlation, I currently avoid the the bottom 25% of the display completely and use 75-90% of HSI displayed power for accelerating to the speed limit, then generally use the cruise control to maintain it. The cruise control does a magnificent job of managing energy in EV mode, by the way. It allows the speed to fall off a bit during a steep climb in order to prevent the ICE from kicking on, and I have never seen it exceed max regen on descents.

Some doubters, which is understandable. We've lived most of our lives driving vehicles that spit out more waste than power when we've stomped on the "Go" button. It is difficult to change our way of thinking.

I have a 10.7 mile closed loop errand route that I have repeated many, many times (gotta start and end any test scenario at the same place in order to cancel out the effect of winds and terrain). I do it with the air conditioning and audio system blasting at the same level, so total loads are essentially the same. Driving the loop conservatively and agressively and getting back to the garage within .3 miles of range remaining at either extreme prompted me into researching this post in the first place. Try it yourself to prove it to yourself. Just be fair, and make it a closed loop, replicating air conditioning and other power draws.

Maybe someone should try and use a modified version of the pulse & glide technique we are using with previous Prius to test this theory.

But instead of using gaz to accelerate & then coasting, this EV technique should use Max EV power as a Pulse and Coasting (No EV power at all) as Glide. Then you could compare this with normal EV driving(just using moderate amount of EV power to maintain speed)

If someone use the same average speed on both techniques and use less charge using the EV Pulse & Glide to travel the same distance, we could consider the theory as valid.

Since I did not receive my PiP yet, someone else wanna try?

We had pretty much squashed that with the regular model. Brisk acceleration didn't result in a penalty. That system very effectively deals with power demands.

The introduction of a plug brought that back again, especially since the larger battery-pack makes it even more difficult to observe the impact.

Thanks for the info to help point out the situation.

Yes, brisk acceleration didn't result in a penalty but do we know if very low acceleration could result in a penalty? If it's true, maybe brisk acceleration followed by coasting would make sense?

u/t, see my post #4. i will try it again briskly and report back.

John,

The last thing I want to accomplish on this forum is to disrespect a guru-level gentleman that I have learned immensely from, so please do not treat the following as a challenge to your wisdom. Nor do I wish to disagree with you, as you are absolutely correct, but for reasons of which you might not be aware.

This post deals with operation of the PiP in EV mode only. In other words, as solely an electric vehicle, a golf cart, a Leaf. I'm talking about only the rarified air of sweet EV performance. It is a range of potential electrical power that exceeds that of the Gen III "regular model" by a factor of roughly 20. My invitation for PiP owners to submit data points extends to those that can complete closed-loop courses of less than 11 miles (or 12 miles with the air conditioning off) using EV only (ICE off for the entire loop) at speeds up to 62mph, not to "regular model" owners that can accomplish the same up to something less than a mile at parking lot speeds. The brisk acceleration of which I speak is recommended to be carried out in EV mode only (ICE off), as opposed to the brisk HV mode acceleration (ICE on and operating at its most effiicient output level) that your previous and immensely informative posts have been utilized by all of us to improve the effeciency of our magnificent Prii in HV mode.

To borrow the words of a cunning linguist... "No disrespect"

Wow, I never knew Georgia was so cool! Thanks for the research.

radio

how high on the hsi do you recommend? just short of power?

Ha Ha! Don't assume the engine comes into play. It could. But the point was misconceptions are difficult to overcome. In this case, it *should* go without saying that EV efficiency offers a obvious gain.

I've noticed the stir the "power" zone (red) discussion has caused, people questioning whether that is a good idea. It builds off of the observations we've made with the 2010 in EV mode. Even though we could see the potential from the EV button, it was a challenge to convey.

I'm impressed by how much the 38 kWh draw from the battery-pack actually delivers. On quite a number of occasions, I've been surprised the engine didn't start... despite "brisk" acceleration.

I cannot credibly recommend any power level without examining Toyota's efficiency curves and getting some reliable intel on mapping of those curves to the HSI display.

As I revealed in a previous post, I'm a dumb-ass newb and assume a 1:1 mapping of the efficiency curve, and further reveal my ignorance by assuming a 1:1 mapping of that curve to the HSI display. Utilizing both faulty assumptions, I accelerate at 75%-90% of the HSI - more out of fear of triggering the ICE than seeking the most efficient acceleration profile.

Too true. In this case it was my misconception reguarding your post. Glad to see we are on the same page.

understood.