It shows:
Engine Coolant Temp
Ambient Temp
Electrical Heater Inlet Temp
Electrical Heater Outlet Temp
Engine Start Request (not functional)
Interior Temperature
Heater Element Activation (as explained in previous email)
Engine RPM (just to see whether the engine is running)
The Mitsubishi Outlander PHEV is a plug-in hybrid vehicle. Not all, but many owners make an effort to use as little fossil fuels as possible. In their attempts, they are frustrated by a design decision by Mitsubishi to start the engine for heating purposes under some conditions. They claim that, under these circumstances, it is more efficient and faster to use engine heat. The first is certainly true from a kWh perspective, but not necessarily what you want. Especially when making a trip well within EV range.
There is an ongoing search for driving / operating strategies or even tools that help minimise or better eliminate engine use for heating on short trips. It all starts with understanding the decision making algorithm (parameters can be ambient temp, interior temp, requested temp, heater and cooland fluid temps, etc.). Creating this chart is part of that quest.
Interestingly enough, it demonstrates that, even when the engine is started to provide heat, the electrical heater is still blasting away. Coolant circuit and heater circuit (which are two parts of a single circuit with a thermostatic valve) are heated up separately. Only when the coolant reaches about 70 deg C, the valve is opened and the circuits connected. At any time, the coolant is hotter than the heater fluid, so why the valve is not opened from the beginning, I don’t know. Perhaps to allow the engine to get to the right temperature faster? But it does not seem very efficient from a kWh perspective, as Mitsubishi suggests.
Also, Mitsubishi says, the engine is only helping ‘to get the heating process started’, but this diagram shows that the engine keeps running even after the heater has been turned off. So, apparently by ‘get the heating process started’ they mean ‘meet the thresholds set in the decision making process’, which involves more than have sufficiently hot heater fluid.
At the beginning of this trip, it was about 7 deg C and I had (purposely) not pre heated. But when I set the A/C unit to 20 deg C, the electric heater started but not the engine. I had to go as high as 24 deg C before the engine would start. But this kept my engine running (what seemed like) forever. At 6::32 and a bit I turned down the A/C unit to 20 deg C and then the engine stopped and the heater took over from there.
Engine activity at the end has to do with empty drive battery, not heating demand. After all, it is a hybrid
