I have another, substantially larger file, that includes climbing a 525 ft (160m) hill at 55 mph (true.) It includes the drive to the hill:
Some quick observations:
- 30 mph indicated - there is almost no power transfered via the electrical path
- 48 mph indicated (50 mph GPS true) - the car appears to run on flat at fairly steady-state, long durations.
- 52 mph indicated (55 mph GPS true) climb 8% grade - the car switches from "energy recirculate" to normal power flow. My eyes suggest the ratio of electrical path to mechanical path does not change that much.
I am happy to share the data from this longer run but it exceeds the quotas allowed in Ecomodder posting. The normalized data is a substantially huge, 252K, file. Post or send me a request for the data and we'll see what can be done. Alternatively, they are at the YahooGroup, 'Prius_Technical_Stuff" in a folder 'Graham Miniscanner Tools.'
I did take the hill climb data and generate this efficiency chart:
Again, higher efficiencies, 85-99%, are found at higher power, normal power split operation. Lower efficiencies, 75-95%, are found at lower power, "energy recirculate" mode. But this is just the electrical power path that takes passes only a fraction of the total ICE power.
Here is a set of data at 50 mph GPS on relatively flat land:
I am not very interested in further analysis of this particular large data file versus working on an improved, data collection system (my GPS receiver arrived and works great.) By integrating GPS and Graham Miniscanner data, we can get a total energy profile with good ephemeris. This can lead to more precise measurements that are likely to improve NHW11 operation. It also brings us closer to tank-to-pavement efficiency, what the owner/driver has to pay 'real money' to achieve.
I have some data from 2007/10/08 from Nashville TN to Huntsville AL:
Notice what happens to MG1/MG2 temperature whenever the speed exceeds 65 mph. Heat, higher temperature, is the signature of lost efficiency. Based upon this data, the maximum, NHW11 Prius speed should be 65 mph.
We can see that the ratio of power that is split between the two paths is a function of load and speed. Furthermore, the normal flow is running at ~80% on the fraction of power that takes the MG1-to-MG2 path, regardless of speed and power. The "energy recirculate" mode is in the 60% range but it also lets the engine turn much slower and in an improved thermodynamic range. The ratio of electrical to ICE power is also a function of vehicle speed and power. Although useful for engineering insights, the driver needs total vehicle efficiency, not just the transaxle efficiency at any single operating point.
Bob Wilson