Hi,

Sir Issac Newton published three great laws of physics:

1. An object in motion will remain in motion unless acted upon by a net force
2. Force equals mass multiplied by acceleration
3. To every action there is an equal and opposite reaction

All of my mileage studies start with these three great laws and in particular, #1 and #2. Notice there is no special clause for how the force is applied, simply that it be applied. With that, I continue to work on an improved Prius performance model backed by experimental data:


One of the primary questions is the drag our vehicle sees as a function of MPG. Ultimately, this determines how much energy is required. Another question is how maximize the efficiency of converting gasoline energy into a force to accelerate our vehicles and/or counter the drag. These same laws apply to all vehicles, not just our Prius.

The reason this is important is there are some 'low hanging fruit' efforts that improve our vehicle performance. These do not require teaching new skills. There are other techniques that need to be quantified and if possible, automated. The more we reduce the operator load and make high efficiency the norm, not the exception, the greater will be our success at reducing the drain of a finite resource, gasoline.

Bob Wilson

 

Right!

 

Hi Bob,
As always, thank you for the interesting graph.

We sometimes do mileage competition driving approximately 20 miles.
On such short driving, we see big impact of battery SOC level change for the results, therefore we adjust the fuel usage using 1% SOC change = 5 cc fuel used equivalent for NHW-20.

Have you ever recorded or compared such SOC level change on a short distance test?

Ken@Japan

 

Thank you Ken,
I haven't used SOC but I do record the battery current and in the past, recorded battery current and voltage. I like to have at least battery current with a presumed voltage of ~300 VDC to get a good idea of battery energy flow with fairly high resolution. I need to go back and see if SOC I can gives enough information to track my energy flows efficiently.

It is interesting about your competitive fuel efficiency contest. In addition to SOC, what protocol or rules are followed for these contests? For example, how the fuel consumption is measured.

Bob Wilson

 

Bob,

Newton is OK assuming that your Prius can't get near the speed of light.

JeffD

 

Thanks, I'll try to stay away from the "Blackhole Expressway" . . . the penultimate glide. <grins>

Bob Wilson

 

Hi Bob,

We use mileage value on the MFD screen. It has to be reset at start point.
- the mpg value is adjusted by trip meter value comparing to standard size distance because smaller tires show longer distance and better mpg value.
- If there are another type of vehicles, we do math the percent ratio to each Japanese 10-15 mode test results.

Ken@Japan

 

Yup, no Einstein needed here. Could you imagine how bad his FE would be near the speed of light?!