Hysteresis cycle affected by pre-heating?

[anko]

Yesterday evening, after a > 100 km trip I parked my car with approx 28% SOC left. A couple of hours later, I pre-heated for just a few minutes, without having the car hooked up to the grid. Of course SOC dropped (shown as the vertical drop off in the red trace of the bottom graph, the Y-axis for SOC is on the right) , but I had not expected it to drop to as low as 21.5%. At least not for the short duration of the pre heating, that is.

But more 'worrying' than the low SOC was the apparent change to the hysteresis cycle, related to the pre heating or not. During the first bit of the return trip, with speeds below 60 km/h, SOC cycled up and down between 21.5% and 23% :shock: (The middle graph shows the engine switching on and off autonomously). This cycle should have been around 26 - 28% or so.

During most of the remainder of the trip, speeds where above 80 km/h. Here, SOC was first cranked up by the car automatically and then started cycling between 27.5 and 29.5%. This should have been between 31 and 32.5%. You can see periods of EV driving being initiated with SOC of 29 - 29.5%, even at speeds above 110 km/h.

After a while, I decided to engage Charge to see if I could further crank up the SOC. I let it go up to 35% before disengaging Charge mode again. Then SOC fell back to 29% and started cycling between 29 and 30.5% (not shown in below diagram). Again, this should have been 31 and 32.5%.

Very strange. Never seen anything like this before. But otherwise, the car behaved totally normal. I would not have noticed anything if it had't been for my OBD tools. For a moment I though my OBD tools were giving false readings, but this morning, directly after a full charge, it showed 104%, which is quite normal.

Thoughts?

 

[maby]

There has to be some inaccuracy in those figures - 6.5% SOC should be close to 1kwh - enough to run the heater flat out for ten minutes or more.

 

[anko]

There has to be some inaccuracy in those figures - 6.5% SOC should be close to 1kwh - enough to run the heater flat out for ten minutes or more.

Indeed. For the time being, I'll assume the inaccuracy, if there was any, was in my statement:

but I had not expected it to drop to as low as 21.5%. At least not for the short duration of the pre heating, that is.

I may well have been close to 10 minutes. Also, on the return trip I had driven about 2 km before measurements started. (Speed right at / after the drop off was > 20 km/h, bakes of this gap) So, probably it was not down all the way to 22.5% at the moment I started the car. But like I said, my concern was not so much the drop itself, but the apparent change to the cycles thereafter.