Tortoise Mode

[anko]

..., when the %SOC got to 22%, the PHEV dropped out of Parallel hybrid mode and into Series hybrid. The speed was just not quite enough to maintain Parallel hybrid.

But higher SOC would not have made a difference then.

I only presented what happened. The PHEV had worked out that the battery was very low in %SOC, and that the series hybrid power would be enough to supply the load demand, so dropped the PHEV out of parallel hybrid, to series hybrid to continue at the same speed.

If the power demand was a bit more than series hybrid could supply, then parallel hybrid may have continued until the turtle appeared for a bit and then power limiting and series hybrid may have been enabled at a new lower power level at reduced speed.

Higher starting %SOC would have enabled a longer period of higher power demands to be maintained by the parallel hybrid mode. Would have easily made it to the top of the range, starting at half the indicated battery gauge. There may be special circumstances with successive long steep hills that could still eventually deplete the battery, no matter what the starting %SOC.

I am still working on some pics of what the PHEV did.

Now you have me confused. First you say speed was not high enough to maintain parallel drive. This could be the case, but would not be SOC related. And now you say that if power demand had been higher than series mode could have supplied, it would have stayed in parallel mode and drained the battery further / faster.

But this can hardly be correct.

At speeds > roughly 120 km/h it will never engage series hybrid mode, so at these speeds SOC or load is not a factor for deciding between series and parallel hybrid mode.
At speeds < roughly 120 km/h, the engine can produce more output in series mode than it can in parallel mode. This is the whole reason for dropping out of parallel mode, either when power demand increases or SOC reaches the very low limits (and thus more power is requested form the engine).

IMHO, the picture you posted shows this: you were requesting a fair deal of power and, although it was less than what the battery could have provided (60 kW nett), this was sourced not just from the battery but also partly from the engine (100% but at limited RPM) because your SOC was already lower than the (26% or 30%) low water mark. Then SOC hit 22% and the car did not want to exhaust the battery even further. So, all power demand had to be sourced form the engine. For this it needed to drop out of parallel mode, at the cost of reduced comfort. 100% at 4100 RPM produced plenty of power to meet the power demand and also recharge the battery a bit (as you noticed). Change in speed and / or power demand had nothing to do with that.