The following shows the Engine Map computed from the OBD II data for the 60 mile commute at 3 F in the previous post #34. I used ICE RPM, % Load, and Fuel Consumption (gallons/minute) data during the trip to compute the chart. The chart is a crude approximation. I don't have enough data to make an accurate map and the data is not all that reliable. For instance, the values of RPM, Load, and fuel consumption are, in general, not synchronized. They are computed at different times. So if I am using data from a time when the ICE is changing RPMs or Load is changing, then the data is suspect. Along the x axis is ICE RPM from 1750 RPM to 2450 RPM. Along the y axis is % Load on the ICE from 65% to 85%. I suspect this is relative load so the chart is distorted. The maximum torque that can be produced by the ICE varies with RPM. This chart assumes it does not vary with RPM. I am using % Load as a proxy for torque.
I simply computed efficiency as RPM * Load / fuel consumption. RPM * Load is proportional to power. So the higher the efficiency, the more power the ICE is generating per quantity of fuel consumption. The car was operating at a constant 2075 rpm and a constant 67.7% load when going 65 mph. This is indicated by the black circle on the map. The car did not appear to be running the generator, so there was no additional load on the ICE other than for propelling the car. In order to provide sufficient power to 65 mph, the ICE has to operate somewhere on the black line.
It looks to me like it is selected a good efficient operating point. If the RPMs were much lower, then efficiency would decrease, i.e. deeper into the purple colored region or one of the other less efficient colored regions (green, red, or darker blue). Faster RPMs may look more efficient on this chart, but the chart is not all that accurate, so I cannot conclude that it would actually be more accurate to operate at higher RPMs. Adding additional load to the ICE would decrease efficiency (the operating point would move up along the y-axis further into the purple, green, red, or darker blue regions), so that could explain why the ICE is not charging the HVB battery. So I suspect the car is doing what it is supposed to do and run the ICE at its most efficient operating point for the power required.
Edited by larryh, 01 February 2014 - 02:14 PM.