Cold weather & save mode - no parallel hybrid

Hi,

My morning commute from Bedford to Milton Keynes involves an 8 mile stretch of derestricted A road. I typically hit save mode on this stretch to save the drive battery for the array of roundabouts through Milton Keynes and this gives me enough drive battery usually to make a similar use of drive battery + petrol on the way home in the evening. On the stretch of A-road on save mode and on the way home (leaving the car to go through its usual cycle), the engine uses parallel hybrid most of the time when the engine is in use.

There was nothing unusual about the journey this morning other than the temperature was 3 degrees, when I started the car I got the possible icy road warning and the engine started as soon as I started the car.

What I noticed on the stretch of A road was that in save mode there was no parallel hybrid displayed on the energy usage graphic on the dashboard, keeping as close an eye as safe I kept watch and parallel hybrid was never used across the entire journey. The temperature never crept above 4 degrees.

I'm curious why this happened, can anyone shed any light on why this might be? My thoughts are that perhaps the car determined that dual motor 4WD was needed for the possible icy conditions? Either that or the torque required from the engine wasn't compatible with the revs needed for engaging the front wheels directly?



Thanks,



Neil.

iPeel said:

I'm curious why this happened, can anyone shed any light on why this might be? My thoughts are that perhaps the car determined that dual motor 4WD was needed for the possible icy conditions? Either that or the torque required from the engine wasn't compatible with the revs needed for engaging the front wheels directly?

Click to expand...

4WD is also possible in parallel mode: engine drives front wheels, rear E-motor drivers rear wheels. You can force this by pressing the 4WD Lock button at speeds > 40 MPH.

I have noticed there are several situations where the car will not engage in parallel mode:

- Of course, when going slower than 40 MPH.
- Or, as you said, when power demand is higher that what can be delivered by the battery + engine (running at the relatively low revs associated with parallel drive). Usually, this will only be during short moments.

But also:
- When the ice is started solely for the purpose of providing heat. Pressing the Charge button should 'resolve' the issue when this happens.
- When there is very little fuel left in the tank. Charge button is no longer working when fuel is very low, so that is not a solution.
- When the ICE was started in maintenance mode (for emissions testing and such).

Last two years, I have noticed the car sticking in serial mode when I select charge mode at a very high SoC (I do this while towing, as my priority then lies with keeping as much SoC as possible). For me this is a good thing, because in serial mode the car is much better capable of maintaining high SoC while towing than it is in parallel mode, again due to the higher revs. I don't know hat has changed, but I am 100% positive the car did not show this behaviour in the first three years of ownership.

In cold weather I did notice that charge button has quite a delay on starting the ICE, I guess the electric heater is used to warm up a bit the engine before start it

As well, I did notice that once pressed charge, it take sometime before switch from a low power serial mode into parallel mode.

I guess when the engine is cold, and the power demand is limited, the ECU has no rush to run full power or high load the ICE until it got warmed up

In other words ... in winter the 1/1.5km of high speed road which I do daily ... I never manage to run it in parallel mode unless I press charge ahead of entering in this road.

Once the engine is "hot" ... it does start immediately in parallel mode when charge is pressed and speed is above 65km/h ... so this can be used only for long trip and alternating EV from ICE mode ... on short trip .. is tricky to use efficiently the ICE (but this is also true for standard cars)

elm70 said:

In cold weather I did notice that charge button has quite a delay on starting the ICE, I guess the electric heater is used to warm up a bit the engine before start it

Click to expand...

Pretty sure this is not the case. The ICE will take a while before engaging parallel mode, as you describe, but I have never noticed any delay in starting the ICE. Okay, it does not get as cold here as it does over there but still. Imagine the thermo valve between coolant fluid and heater fluid opening when coolant fluid is really cold. The cabine heater would become very cold instantly.

elm70 said:

As well, I did notice that once pressed charge, it take sometime before switch from a low power serial mode into parallel mode.

I guess when the engine is cold, and the power demand is limited, the ECU has no rush to run full power or high load the ICE until it got warmed up

Click to expand...

Indeed, there is a built in warm up phase (but not when the ICE is started because of high power demand, in that case high power is 'instant', although in serial mode). During this warm up phase you will keep draining the battery. The faster you go, the more you will drain the battery during thwart up phase. This is why at higher speeds the ICE starts at 30.5% SoC where at lower speed it might start not before reaching 25.5% SoC.

Interestingly enough I have not noticed differences in thresholds depending on outside temperature.

Thanks Anko, I think in my case it was most similar to your "When the ice is started solely for the purpose of providing heat. Pressing the Charge button should 'resolve' the issue when this happens." case.

The temperatures in the morning are up again so I've not had a chance to test, but next time I'll try cycling through charge mode to see if that engages parallel hybrid and advise.


Cheers,


Neil.