F1 Energy store density for 2026 and hot swap batteries

[Farnborough]

Doesn't really matter does it? You could adjust the duration or whatever to generate more power at idle...or even raise the idle speed.

I guess at the end of the day, it comes down to whether you burn more fuel energy than you generate in electrical.

If you load the engine with the MGUK to generate a useful amount of energy, the engine isn't really at idle, even if it is at nominal idle speed.

When the engine is at "IDLE" the engine cannot be "loaded with the MGU-K to generate any amount of energy, because when the engine is at ''IDLE'' the car is not moving. Fertile imagination at its best.

Well....at "IDLE"........virtually all engine are controlled for load etc to achieve target rpm, even the most basic production cars let alone level of monitoring availability on these power units.

They monitor at real time flywheel speed even down to cylinder by cylinder frequency to give assessment of parity etc in pulses arriving at target or plus and minus deviation.

All engine will have variance in load for "IDLE" phase, with variance in ancillary drag being the primary reason. Ecu will observe outright rpm as target specification, with any additional drag on crankshaft almost irrelevant.

Adding a brake (mgu K generator) will easily be accommodated and still with the asked for rpm target being achieved.

Entirely possible, but suspect (think there's requirement to only be active when braking system is used) it may be outlawed by regulatory demand.

[saviour stivala]

Yes. It is because of the requirement of it being active (harvesting) energy from the brakes, and for such harvesting to happed, the car need be on-the-move, is why I wrote what I did re-loading MGU-K
on ICE at idle. and by the way, what takes care of ICE load at idle in F1 is the anti-stall programed in.

[Tommy Cookers]

Well....at "IDLE"....
.....Adding a brake (mgu K generator) will easily be accommodated and still with the asked for rpm target being achieved. .....

F1 idle is a dedicated regime (of extensive migrating cylinder deactivation) that is outside the mandated PU torque map

the map restricts fuel rates below 10500 rpm, slightly starving the ICE (partly to compel those exciting high revs)
eg at (50%) 5250 rpm the max fuel rate isn't (50%) 50 kg/hr - it's less

so in 2026 a (say) 420 kW/10500 rpm ICE would have c.190 kW at 5250 rpm (assuming no turbocharging limitations)
the K could (in principle) correspondingly generate at c.180 kW
but wouldn't the ICE need a big radiator cooling fan ?

[Farnborough]

Well....at "IDLE"....
.....Adding a brake (mgu K generator) will easily be accommodated and still with the asked for rpm target being achieved. .....

F1 idle is a dedicated regime (of extensive migrating cylinder deactivation) that is outside the mandated PU torque map

the map restricts fuel rates below 10500 rpm, slightly starving the ICE (partly to compel those exciting high revs)
eg at (50%) 5250 rpm the max fuel rate isn't (50%) 50 kg/hr - it's less

so in 2026 a (say) 420 kW/10500 rpm ICE would have c.190 kW at 5250 rpm (assuming no turbocharging limitations)
the K could (in principle) correspondingly generate at c.180 kW
but wouldn't the ICE need a big radiator cooling fan ?

Yes, agree with question about cooling. I dont believe they charge in this way (nothing around to say they do that's readily quotable) more that I was writing to dispel "savior stivala" contention that IDLE was nothing more sophisticated than a completely bland/fixed setting in any engine control strategy.

[wuzak]

Ant Davidson made a comment in FP1 that the change in the layout for the Barcelona track has reduced the amount of energy that can be recovered from braking.

Begs the question, if braking is the only way to recover energy in 2026, will the ERS be largely ballast at such tracks?

[Hoffman900]

The paper I linked earlier and co-authored by Ferrari explained it this way:

Figure 12 shows the most significant optimal state and input trajectories for two different battery recharge targets and the same fuel consumption target. The considered portion of lap is the section between the points A and B in Figure 11. It can be noticed that the gearshift strategy is different: not only is the 8th gear solely engaged for the battery discharge case (∆Eb,target = −0.3 MJ), but also several upshifts occur earlier compared to the battery recharge case (∆Eb,target = 0.5MJ). This trend can be attributed to the abundance of electrical energy at disposal: the gears are selected to maximize the overall engine power and therefore the propulsive power. For the battery recharge case, however, the trade-off between the engine power and the MGU-H recuperation is more pronounced. The fact of not shifting into the 8th gear keeps the engine speed high and therefore the pressure in the intake manifold lower (compared to the battery discharge case). As a consequence, the compressor power is lower and more power can be recuperated by the MGU-H. The power unit control around the upshifts occurs each time in a similar manner: the MGU-H recuperates less to accelerate the turbocharger shaft, whilst the throttle valve is operated to achieve the optimal fuel-to-air ratio value. The battery recharge target also influences the waste-gate operation. In conventional gasoline turbocharged engines, the waste-gate is operated to diminish the turbine power and thereby controls the intake manifold pressure [79]. By contrast, for the considered high-performance power unit the waste-gate is used to increase the engine power by diminishing the exhaust manifold pressure. The turbine power extraction is reduced and therefore the MGU-H power recuperation goes roughly to zero (when no upshift is taking place). The intake manifold pressure is not affected, the engine pumping power increases and so does the overall engine power. In addition to that, the MGU-K operation is also influenced by the battery availability. Not only the MGU-K cut occurs later on the straight if more battery energy can be deployed, but also the slope is different: the analytical explanation for this can be found in [58]. Finally, the optimal behavior in the corner is analyzed. The optimal cylinder deactivation is mainly the same, except at the corner exit. In this region, for the battery discharge case, slightly more fuel is injected. At the same time the spark-advance is slightly retarded and produces a lower spark-advance efficiency. This causes a small increase in the exhaust manifold temperature and pressure, allowing the MGU-H to recuperate more. The procedure of converting a small portion of fuel energy into electrical energy through the increase of the exhaust manifold temperature is possible in the cases where the battery recharge targets allow it. For the battery recharge case, this operation only occurs for a very short amount of time, since every drop of fuel counts and the gearshift strategy is not aimed at maximizing the engine efficiency, but rather finding the optimal trade-off between the internal combustion engine and the energy recovery system.

It’s worth a read and they have a bunch of figures showing what this all looks like around a lap.

I too am curious how 2026 plays out with the rules as I know it.

[AR3-GP]

The paper I linked earlier and co-authored by Ferrari explained it this way:

Figure 12 shows the most significant optimal state and input trajectories for two different battery recharge targets and the same fuel consumption target. The considered portion of lap is the section between the points A and B in Figure 11. It can be noticed that the gearshift strategy is different: not only is the 8th gear solely engaged for the battery discharge case (∆Eb,target = −0.3 MJ), but also several upshifts occur earlier compared to the battery recharge case (∆Eb,target = 0.5MJ). This trend can be attributed to the abundance of electrical energy at disposal: the gears are selected to maximize the overall engine power and therefore the propulsive power. For the battery recharge case, however, the trade-off between the engine power and the MGU-H recuperation is more pronounced. The fact of not shifting into the 8th gear keeps the engine speed high and therefore the pressure in the intake manifold lower (compared to the battery discharge case). As a consequence, the compressor power is lower and more power can be recuperated by the MGU-H. The power unit control around the upshifts occurs each time in a similar manner: the MGU-H recuperates less to accelerate the turbocharger shaft, whilst the throttle valve is operated to achieve the optimal fuel-to-air ratio value. The battery recharge target also influences the waste-gate operation. In conventional gasoline turbocharged engines, the waste-gate is operated to diminish the turbine power and thereby controls the intake manifold pressure [79]. By contrast, for the considered high-performance power unit the waste-gate is used to increase the engine power by diminishing the exhaust manifold pressure. The turbine power extraction is reduced and therefore the MGU-H power recuperation goes roughly to zero (when no upshift is taking place). The intake manifold pressure is not affected, the engine pumping power increases and so does the overall engine power. In addition to that, the MGU-K operation is also influenced by the battery availability. Not only the MGU-K cut occurs later on the straight if more battery energy can be deployed, but also the slope is different: the analytical explanation for this can be found in [58]. Finally, the optimal behavior in the corner is analyzed. The optimal cylinder deactivation is mainly the same, except at the corner exit. In this region, for the battery discharge case, slightly more fuel is injected. At the same time the spark-advance is slightly retarded and produces a lower spark-advance efficiency. This causes a small increase in the exhaust manifold temperature and pressure, allowing the MGU-H to recuperate more. The procedure of converting a small portion of fuel energy into electrical energy through the increase of the exhaust manifold temperature is possible in the cases where the battery recharge targets allow it. For the battery recharge case, this operation only occurs for a very short amount of time, since every drop of fuel counts and the gearshift strategy is not aimed at maximizing the engine efficiency, but rather finding the optimal trade-off between the internal combustion engine and the energy recovery system.

It’s worth a read and they have a bunch of figures showing what this all looks like around a lap.

I too am curious how 2026 plays out with the rules as I know it.

This makes the 2026 regulations and the removal of the MGU-H seem so boring.

[diffuser]

It’s worth a read and they have a bunch of figures showing what this all looks like around a lap.

I too am curious how 2026 plays out with the rules as I know it.

This makes the 2026 regulations and the removal of the MGU-H seem so boring.
[/quote]

Agreed.....so sad.

They went against front brake regeneration cause Audi had too much experience....Sad, that would have helped somewhat.

[wuzak]

They went against front brake regeneration cause Audi had too much experience....Sad, that would have helped somewhat.

As additional power recovery, or in place of the engine MGUK?

If it is additional, that is even more weight to these heavy cars, and if it is instead of the engine MGUK you have a 4wd F1 car.

As regards front brake regeneration, Alpine and Ferrari both have LMh prototypes with front MGUK, as per the regulations.

The fact is that they ditched the MGUH to get Audi.

[saviour stivala]

''The waste-gate is used to increase engine power (free-load-mode) by diminishing the turbine power". Because the waste-gate of a formula 1 turbocharger is not build-in into the turbine housing, when open exhaust gases bypass the turbine. On a normal turbocharged engine with the waste-gate build into the turbine housing, the exhaust gases released by the waste-gate are the same gases that goes inside the turbine housing. So waste-gate is acting more like a pressure release valve than a bypass valve.

[CaribouBread]

The more I think about these new regs, the more i'm expecting the racing to be WEC style end-of-straight lift and coast, don't mind it in endurance racing but maybe it'll help overtaking?? trying to look for positives

[diffuser]

The more I think about these new regs, the more i'm expecting the racing to be WEC style end-of-straight lift and coast, don't mind it in endurance racing but maybe it'll help overtaking?? trying to look for positives

Why would you coast?

Lots of braking with rear bias, no?

[wuzak]

The more I think about these new regs, the more i'm expecting the racing to be WEC style end-of-straight lift and coast, don't mind it in endurance racing but maybe it'll help overtaking?? trying to look for positives

Why would you coast?

Lots of braking with rear bias, no?

No, I think they will start recovery part way along the straight, at up to 100kW, while the driver is at full throttle.

I believe that's what they used to do in the LMP1 days - get up to speed in first part of straight, reduce power to save energy then start recovering before the braking zone.

Under LMh and LMDh rules it is a bit different.

For these the power curve is defined, and your engine can produce more power than the total allowed, which means that when the ICE is producing maximum power the ERS can be recovering, to be used when the ICE is below the power curve.

[diffuser]

The more I think about these new regs, the more i'm expecting the racing to be WEC style end-of-straight lift and coast, don't mind it in endurance racing but maybe it'll help overtaking?? trying to look for positives

Why would you coast?

Lots of braking with rear bias, no?

No, I think they will start recovery part way along the straight, at up to 100kW, while the driver is at full throttle.

I believe that's what they used to do in the LMP1 days - get up to speed in first part of straight, reduce power to save energy then start recovering before the braking zone.

Under LMh and LMDh rules it is a bit different.

For these the power curve is defined, and your engine can produce more power than the total allowed, which means that when the ICE is producing maximum power the ERS can be recovering, to be used when the ICE is below the power curve.

That's what I'm hoping but alot of people in this forum are suggesting that you cannot use the ICE to drive the MGU-K to charge the battery.

[saviour stivala]

Yes. Even the RBPT power unit project leader engineer when talking with RET said that running the MGU-K by the ICE will not be permitted by the 2026 power unit rules.