Fuel consumption in relation to Drive battery levels.

[gwatpe]

I have to be brief Anko. I had no recording of OBD data, only the S.O. writing down numbers as I was flipping between menus on the dash and MMCS as well as the HUD. Almost a year ago now as well.

The battery had been completely emptied and the petrol was very close to empty as well, and I filled the petrol tank up. Seemed a good time to see what CHARGE mode actually did when driven at constant speed of 100kph and 110kph. Happened to drain the petrol to very close to empty on 2 occasions. Once getting to Alice Springs and then Tennant Creek. I now travel with a spare reserve can of fuel and a slightly different driving style.

Only recently I have been unable to record long term data with your mod for Torque, and EvBatMon has no direct recording function. Without the recording of petrol and electric data, it is very difficult to get objective data.

 

[gwatpe]

Even though this thread appears on another main topic, I have repeated a trip to the city drive when letting the battery run down over the day. Arrived home with "--.--" for battery as well as Total range, with no bars on either battery or petrol gauge.

As the battery was depleted the PHEV economy calculation went up from 6.5L/100km to 7.1L/100 km when I got home, for a trip of 190km with all the battery used over the day.

I achieved better economy the last time for a longer drive, and getting home with 6bars in the battery.

Also interesting was the calculated total range after the tank was brim refilled of only 458km. The PHEV knows the tank holds 45L and worked out that with a flat battery and a full tank that economy would be about 10L/100km.

I am not convinced that economy returned with my driving needs, works any better with an empty or half empty battery.

 

[maby]

Even though this thread appears on another main topic, I have repeated a trip to the city drive when letting the battery run down over the day. Arrived home with "--.--" for battery as well as Total range, with no bars on either battery or petrol gauge.

As the battery was depleted the PHEV economy calculation went up from 6.5L/100km to 7.1L/100 km when I got home, for a trip of 190km with all the battery used over the day.

I achieved better economy the last time for a longer drive, and getting home with 6bars in the battery.

Also interesting was the calculated total range after the tank was brim refilled of only 458km. The PHEV knows the tank holds 45L and worked out that with a flat battery and a full tank that economy would be about 10L/100km.

I am not convinced that economy returned with my driving needs, works any better with an empty or half empty battery.

This pretty much matches my experience, gwatpe. I agree that there are theoretical grounds to expect that fuel economy should be better with a low state of charge, the real difference seems to be too low to measure against the noise background of normal driving.

 

[anko]

As the battery was depleted the PHEV economy calculation went up from 6.5L/100km to 7.1L/100 km when I got home, for a trip of 190km with all the battery used over the day.

When did you record the 6.5? And when the 7.1?

 

[gwatpe]

The battery was depleted at the top of the steep hill on my way home from the city. I was flicking through the menus and saw the 6.5L/100km. In the 40 or so remaining km, the economy number went up to 7.1L/100km. The PHEV had been using the battery during the drive, and there were many stops, and I toggled save whenever the ICE was running when I had to stop. The SAVE setting would have continued to be reset lower over the day.

The previous drive was longer, and there was more battery remaining at the end of the trip. SAVE had been toggled in a similar way as above on this trip as well.

The drive is a real drive, with a mix of highway, hills and bends, and city driving.

I think that the controlled flat terrain, controlled speed, experimental driving that has been gathered by forum members including some of my own experiments is somehow biasing the data. The PHEV seems to be very sensitive to driving conditions and driving style, and this is probably affecting the returned petrol economy more than how much capacity is left in the battery. Too many variables to measure and correlate the data, and unless I was paid handsomely and supplied with an appropriate tool set for the job, I will just be content with the economy returned. Normally quite good by the way. I have however recorded better petrol economy with the battery capacity at 50% on the gauge, than when full. The use of the battery by the PHEV does make this measurement subjective and it may still be that only in controlled conditions will any difference be recorded.

 

[maby]

...

I think that the controlled flat terrain, controlled speed, experimental driving that has been gathered by forum members including some of my own experiments is somehow biasing the data. The PHEV seems to be very sensitive to driving conditions and driving style, and this is probably affecting the returned petrol economy more than how much capacity is left in the battery. Too many variables to measure and correlate the data, and unless I was paid handsomely and supplied with an appropriate tool set for the job, I will just be content with the economy returned. Normally quite good by the way. I have however recorded better petrol economy with the battery capacity at 50% on the gauge, than when full. The use of the battery by the PHEV does make this measurement subjective and it may still be that only in controlled conditions will any difference be recorded.

From our ten years with a Prius, I would say that hybrids do tend to be more sensitive to road conditions and pattern of usage than conventional cars. It's not surprising really - the object of all that technology is to make them more efficient and hence there is less energy wasted and any change in loading will have more effect. The big 4 litre turbo charged diesel in a Landrover or Landcruiser is sitting there wasting power when it is lightly loaded, but the increase in fuel consumption in percentage terms is less than for the PHEV as load is applied.