Hi everyone,
a couple of days ago, I made
a post in the F1 Car & Hardware Development > 2026 F1 Cars - General Thread regarding ERS-K recovery - especially under partial load.
I only discovered this very thread here afterwards, were a lot of this was already discussed to a certain degree. So after having read through this, I was able to answer some of my questions and to fix some of my previous errors.
But some things are still not clicking for me...
ERS-K recovery from ICE power under partial load
The chart below is a refinement of the one in the post linked above, showing the potential of what could be harvested under partial load.
- The dark green area is the theoretically harvestable power from the ICE - which is derived from C5.2.5 assuming a (IMHO still challenging) TE of 48 %.
- The blue dots are the needed min. RPM (x1000) according to C5.2.4 - again assuming 48 % TE. This of course means, that you need the right gear for the desired speed in a certain corner.
- The 50 kW base ICE output at/below -50 kW power demand might be intended to just keep the ICE from stalling - so there will not be much to harvest.
- So between 0 kW and 300 kW power demand something between 100 kW and 170 kW could be harvestable - not nothing, but quite a bit less and on a narrower power demand band than I had initially thought.
Aside from having it gotten totally wrong, questions that I could not answer myself until now:
- Is power demand only derived from the throttle pedal or also from the braking pedal?
- If it is only the throttle pedal, is -50 kW the minimum value which stands for minimum Engine Braking? Or could it be possible to have the throttle pedal mapped from -350 kW to750 kW, making it a bit like "One Pedal Driving" in a BEV? Coincidently, there was a rule in an earlier revision of the Technical Regulations prohibiting certain points (like for example the 0 kW point on such a wide band) to be marked (felt by the driver). This rule seems to have vanished.
- If both, how does it get aggregated? Adding both, ignoring the throttle pedal as soon as one hits the brake pedal, something else?
Full throttle ERS-K behaviour
The below chart basically shows the corridor of allowed full throttle behaviour as prescribed by the rules as I do understand it.
- The lower bound is defined by:
C5.12.4
Except for conforming to Article C5.2.8, the driver maximum power demand cannot be reduced by
more than 150kW at the start of any full Throttle period and the power reduction will remain fixed
for a minimum of 1s.
Earlier, it said, that the ERS-K needed to provide at least 200 kW for the first second during full Throttle.
5.12.6
Unless the electrical DC power of the ERS-K is negative, the driver maximum power demand must
not be reduced at any greater than the rates defined below:
a. 50kW in any 1s period at Competitions where the FIA determines that the power limited
distance exceeds 3500m. [...]
b. 100kW in any 1s period at all other Competitions.
- The upper bound is more a rough guesstimate for a scenario, where full throttle starts with 200 km/h leaving a corner, acceleration to 290 km/h in 2,5 seconds and reaching 345 km/h after 13,5 seconds.
C5.2.8 defines the downslope of ERS-K output depending on speed.
So far, so good. I cannot imagine someone to use the lower bound under normal circumstances, as you would basically be a sitting duck with 150kW combined power against 750 kW of others.
But who or what controls the actual behaviour for a specific full throttle case? Will the drivers get presets between which to choose from straight to straight? Is it derived from the depletion rate beyond just preventing instant jumps from 350 kW to 0 kW? Or am I misunderstanding this and the lower bound does not define what might happing during full thottle, but what is allowed to happen when a driver lifts his right foot?
Could anyone shed some light on this?
