pulse & glide... accelerate fast or slow?

As everyone wrote, my recommendation for acceleration(pulse) is also not use the battery power, which means no yellow arrow from battery is not shown on the MFD energy screen.

Ken@Japan

 

If I remember, I 'll check that out on my way home this evening.

RPM progressively increases with speed with steady pedal position. At higher pulse speeds (30-40), 50% might put you above 2400. When I first read Ken's 40% number, I watched for the relationship between pedal position and RPM for awhile, and found that 40% would put me above 2000 (sorry, can't remember now what) after I crossed 30 MPH.

Problem is, for those without added instrumentation, where is 40% in the pedal's range of travel? 50%? [x]%? It will be subjective and imprecise. For the average driver it really doesn't matter too much. But I'm assuming most participants in this thread want more than the average. The iMPG/MPH relationship is objective and measureable without add-ons.

 

This just goes to show how valuable it is to share information. I've learned more on how to properly drive a Prius in this post than I have in the few years I've had it.

I always thought that more EV the better. I was never sure about P&G, and had never heard the term "hypermiling".

So thanks Priuschat members!

 

Thanks, if you do, that would be very interesting for me.

Yes, your'e right, that's almost as simple, and much more accurate. My own personal special problem is just that my Prius doesn't display mpg.

 

Ok, for us Canadians/Australians/Europeans with L/100km and km/h, has somebody already done the unit translation of this iMPG/MPH thing so we all don't have to?

 

At a pedal position of near 50%, RPM is already 2400 at 25 MPH. By the time speed gets into the 35-40 MPH range, RPM tops 3000.

I also verified that near 40%, RPM is around 2200-2400 at about 30 MPH.

Sorry for the imprecise terms "near," "around," and "range." I didn't want to hang around long at those high RPMs and wreck my MPG.

Ah-ha, I didn't bother to notice you're in Deutschland! Forgive me. :redface: Are you a native German? You type English very well!

 

For people like me who imported a car from the US and drive with KPH the relationship is iMPG about 1/3KPH (0.3125 more precisely). I was checking driving home tonight and it is a close match how I've been driving with the exception of a short entry ramp into HWY traffic.
Gabe

 

I'm with you Ken, keep it simple.

As for energy used to accelerate slowly, try accelerating to a set speed, say 40mph at very light throttle and you can see the MFD will show a mile of higher than average fuel use but accelerate quickly, say at half throttle and your up to speed in a flash and coasting with no energy consumption happening on the MFD.

I pretty much ignore the power flow to and from the battery when accelerating, I do such short bursts it isn't a priority. Now that I only use my AC for 1 way on my commute I'm back to 4.3L/100km

 

So is your instantaneous mileage reading in mpg or L/100km?

 

So after reading this thread and other related threads, it seems that this car would be more MPG efficient ifit didn't have the electrical capabilities at all. It seems that using the electric part of the car is inefficient. so why not just have a 1.5 L prius w/o the electric motor?? If you say for the added TQ(which is very beneficial) then that is a contradiction since the aim is NOT to use the electric motor... right???

I gues I'm trying to figure out if a similar sized non hybrid prius was driven "pseudo-hypermiling" .... would it get better MPG due to no electric recharging interference?

 

Thanks for checking that out for me! It looks like either I don't press down quite as far as I thought, or I am running slightly higher revs than I thought.

Nothing to forgive! I am an American. My English is getting a little rusty, and actually I never did type very well, but my assistant, Ms. Word helps a lot.

 

The only option I have between imperial and metric is the speedometer can be toggled between MPH and KPH. Driving on Canadian roads most times I have it on KPH. The fuel consumption readings are all in MPG and no one has been able to figure out how to change it to metric (probably some country coding in the programming). There a number of us who imported our cars from the US and that is why I posted the conversion for "ideal acceleration":
iMPG = 1/2 MPH translated to situation similar to mine of
iMPG = ~ 1/3 KPH
Hope this helps,
Gabe

 

The Prius is indeed efficient in part because of the engine size. But as a 3000 pound car, it would be underpowered with the ICE only. The electric motor provides an immediate and substantial boost when needed for rapid acceleration. So yes, staying out of the battery is good for efficiency, but using it when needed is good for get-up-and-go.

Any car can benefit from hypermiling techniques, but nothing among currently available non-hybrid cars will top the Prius, especially any approaching its size and weight. Take a look around on CleanMPG and you can see real-world results from hypermilers driving a wide assortment of vehicles.

 

PAPARYNO,
Well actually it isn't possible to not use the electric motors and get a Prius rolling unless you're on a hill.
Some of the power from the low torque 1.5 litre Atkinson cycle ICE is channelled through MG1 then into MG2 which can produce lots of torque, this is torque requires to get the car moving. The battery is for storing energy, it will store otherwise wasted brake energy but only 1/3 of that energy makes it back to the wheels. This is similar to the use of energy to charge the battery, only about 1/3 of the energy from the ICE which is stored in the battery makes it from the ICE to the wheels, the rest is lost in noise, heat etc. while changing from kinetic energy to electric to chemical to electric to kinetic.

Without the electric boost of the battery MG2 would not be able to produce full power as it would only be fed by a 30kW generator but is capable of handling 50kW so it gets the extra power when needed from the battery.

A conventional car however needs an ICE which can make all the power needed for maximum acceleration even though that power will only be needed momentarily and occasionally. Because of this a conventional car needs to have a large powerful engine which isn't optimised for maximum efficiency.

By avoiding using the battery you benefit from the hybrid technology because it is the battery and electrics that allow such a small light and efficient engine to be used. A Toyota Yaris has the same size engine as a Prius, in fact it is made from the same castings although machined differently and the Yaris is smaller and lighter but because of HSD the Prius has lower fuel consumption and better acceleration than the smaller lighter Yaris.

 

To add to patsparks post: The Prius always uses the electric motors when it moves. At the heart of the HSD is a fixed planetary gearbox which splits the torque from the ICE. Part of the torque goes directly to the drive train (to which MG2 is also connected), and part goes to MG1. The ratio of this torque split is fixed and cannot be changed by the control system, nor can any part of the system be disengaged. The only factor that can be adjusted is how fast the various parts spin, and how much electricity is applied to or drawn from the MGs. Power is delivered from the ICE to the wheels through two paths: 1) Directly from the ICE through the torque splitting device, and 2) Indirectly from the ICE by way of the two MGs. In the second method, the ICE spins MG1 which makes electricity; this electricity is routed to MG2, which applies torque to the drive train. This direct and indirect method of applying torque to the drive train normally occurs simultaneously. The ratio of power sent through the two paths determines the effective gear ratio.

So where does the battery fit into this? The battery is used as a buffer to store extra energy when it is available and deliver it when needed.

To summarize this post and patsparks observation, it is impossible to drive a Prius without using the electric motors, but it is possible to mostly avoid using the battery.

Tom

 

Anybody else then? or will I have to get my pencil out and sharpen it? What's the instantaneous L/100km to km/h ratio for optimum acceleration.

 

If MPH to MPG are best kept at a constant ratio of 2:1 then the L/100km to km/h is going to be an inverse relationship because MPG is inverse to L/100km. That is as L/100km goes up MPG comes down.

Too hard for me at nearly 1:00AM.
I think you need a graph.

 

Following up to everyone's comments, avoiding the battery power does not mean you're not utilizing the hybrid system.

The PSD works something like an electric torque converter (eCVT).
The Atkinson cycle ICE runs very efficient torque*rpm combination for the reqired power.

Please refer to attached figure.
The blue part (Generator -> Motor) is the electric torque converter part.
It is not recommended to use the white part of battery power (Battery -> Motor).
TOYOTA: Company > Technology

Ken@Japan

 

As patsparks stated I don't think you can establish a simple relationship for l/100km vs KPH that you can easily use when driving. I tried to translate the numbers in my spreadsheet and could not come up with a simple formula. I think patsparks is correct that it's a curve. IMHO you need more than a pencil ... start with a slideruler at least or try this conversion site and see if you can establish a (simple) relationship:
Unit Conversions
Gabe