Looking to change gas motor activation point

Hi Mica...,

The Prius has a battery management routine which tries to keep it at mid-scale on the State of Charge (SOC) meter. It can get down to two bars, for example, when the car in stop and go traffic, running the AC. But in most traffic it tries to keep the battery at mid charge. Your probably should not fight the car to run the battery down. The purpose of this is to make for a long battery life. Consequently its not adjustable. You will notice that is the weather gets warmer, the car will let the battery go to lower SOC.

If your goal is to get the best mileage, keeping the battery up above mid charge is advantageous. When the battery is above half SOC, one can generally drop the car into glide (no-arrows) below 40 mpg or stealth (electric drive ) from 40 to 45 at will. With the SOC below half, the car will bring the engine on with the slightest demand for accelleration.

There is an EV switch sold. With the EV switch, one can drive the car around below 34 mph in full electric mode, with allot more accelleration. I do not have one of those, so I do not know how low it lets the battery go.

The hybrid concept is not so much to have an EV car, deplete the battery and then charge it back up with the engine pushing the car and charging at the same time, as it is for the battery to supplant the smaller engine during acceleration, and the smaller engine charge and cruise the car inbetween. That way the the engine load is leveled into its most efficient range. Not too much during accelleration, and not too low during cruise. Its this very low power level during cruise that is the real bugaboo for the common gasoline engine. Efficiency at partial power is very poor at these low levels. As bad as one half the best efficiency in a Otto cycle car, or 10 to 15 %. This is the reason most cars get around 20 mpg in city driving. The Atkinson cycle engine in the Prius is at 25 % efficiency at 12 HP output power (highway cruise horsepower most likely) as tested by Argonne National Lab. Which is very good. All the energy comes from burning gasoline in the engine, so the more efficiently that happens, the better the mileage.

 

Doing that will lower performance and mileage, and increase wear and tear on the battery and some drive components. Toyota has already spent a decade optimizing the control system for the Prius, so it is improbable that it can be improved with tinkering. What you might want to do is add the EV button, which will allow more control over the electric mode. The EV button is standard on Prius outside the U.S., so it is a relatively easy installation. Searching PC will give you a lot of information on EV.

Tom

 

<div class='quotetop'>QUOTE(MicaAngelo @ Apr 18 2007, 10:43 PM) [snapback]425762[/snapback]</div>

One item that many hybrid buyers/owners (and to those who are interested in the Prius operation) seem not realize is ALL the power to vehicle comes solely from the ICE (Internal Combustion Engine). Generally with the Prius (though not always) it is more efficient to have the ICE supply power directly to the wheels and not have to waste power through the generating and storage operations associated with the electric motor.

While it is good to think "outside the box" (look what Felix Kramer and his associates have done to promote the Prius PHEV (Plug in Hybrid Electric Vehicles)), one can ascertain that Toyota and their engineers have spent hundreds of thousands, if not millions of dollars, in developing and researching the algorithms necessary to ensure maximum fuel economy and also balance the reliability of its associated components with regards to a stock Prius.

What you are trying to achieve is how a typical PHEV would operate. But with a PHEV you would have much larger capacity batteries designed to deep cycle on a continual basis and you would also have to ensure the electric motors and the transmission would be cooled properly when in the EV mode.

Rick
#4 2006

 

The EV mode exist in France, directly "made in Toyota". I think it is nothing more than a gadget, just able to run the car for 2 km max. (1,18 mile) in the best conditions. My 2006 Prius never did more than 1 km in this mode, until the engine goes on ... It is only convenient to pull the car out an underground parking without gas pollution ... if the main battery is fully charged. My idea is that it is not very interessant to spend time and money for that.

For the Priuschat members who can read French, visit our forum in France : priustouringclub.com

Best regards.
François

 

Donee's explanation is correct. Changing the Prius's operating parameters would reduce your fuel efficiency and at the same time, put excessive wear on your battery.

Toyota knew what it was doing. Trust it.

The EV switch can help in very limited circumstances. NOT to force the ICE to cut out sooner or to stay off longer, but in the kinds of rare situations that the car cannot anticipate. And it is a fun gadget.

There is really no way to do what you are asking, short of re-programming the car's computer. Think you can do that better than Toyota can? I don't. Welcome to Prius Chat and enjoy your car.

 

All of the above + you would probably be altering
the emission profile too.

And that's why I bought the car. Everything else is just gravy.

 

<div class='quotetop'>QUOTE(MicaAngelo @ Apr 18 2007, 09:43 PM) [snapback]425762[/snapback]</div>

You might consider mastering the "Gas Engine activation points" and changing your driving style and route to maximize performance. We call it 'route planning' and it works very nicely.

Bob Wilson

 

I agree everyone's comments.
http://hybridcars.about.com/od/ownership/a/pulseandglide.htm
The typical technique for the best mileage is the Pulse&Glide, then avoid to use the battery power.

Ken@Japan

 

Michael, you ought to present your new efforts at

www.cleanmpg.com

where they will be especially appreciated, and additional hints abound.

 

The only thing I use my EV button for, is on cold days, when the engine is not yet warm and I have to wait a long time for a red traffic light, to force the engine off. When the light turns green, I switch back to normal mode.
That way the engine warms during driving, and not wasting fuel while standing still.

Is this a good idea?

 

<div class='quotetop'>QUOTE(Sho-Bud @ Apr 23 2007, 06:13 AM) [snapback]428250[/snapback]</div>

My feeling is that this is a good idea if and only if the battery SOC is high and the engine is warm. If the SOC is low, the engine will burn extra gas while driving to bring the SOC up, and if the engine is cold you want it to warm up anyway. So: cold engine and low SOC: let it run. High SOC: shut it off with the EV switch.

I use the EV switch a lot when:

The engine is warm and the SOC is high, but it won't go into electric itself because I have not encountered a long enough stop to get it into Stage 4 operation; and I am in a residential neighborhood with a lot of stop signs.

Then:

I allow the gas engine to run during acceleration, and then shut it off with the EV switch once I've reached speed. At the next stop sign, I start the engine again to accelerate back up to speed. This is easy to do because I have the Coastal EV switch, which uses the c/c stalk, which is right at my finger while driving, and I can operate it without taking my hand off the wheel or my eyes off the road.