F1 Energy store density for 2026 and hot swap batteries

[wuzak]

2026 Cars.
Fuel allowed per race: 70kg*
Fuel energy density: ~40MJ/kg (between 38 and 41 MJ/kg allowed)
Potential Fuel Energy per race: 2800MJ
Assuming 50% efficiency, the actual energy used to propel the car is 1400MJ = 388.9kWh

* From statements by Pat Symonds that the 2026 cars could do a race with 70kg of fuel if front wheel recovery is used.

Front wheel recovery has been been vetoed by the teams, hasn't it? Something to do with worrying that Audi will be much better at it than the rest thanks to experience elsewhere.

I doubt it had anything to do with Audi, but rather weight and cost, since the chassis would have to be completely redesigned.

Ferrari will have had 4 years experience racing with front wheel MGUK by 2026, plus several thousand miles testing.

Honda will have similar experience with the Acura LMDh prototype. Renault/Alpine will be doing LMh with front wheel MGUK.

Mercedes won't have racing experience, but they have EVs on sale with front and rear MGUs, plus they have developed the AMG One over many years, with its front wheel recovery (to go with rear wheel recovery and MGUH).

I don't think it would be especially difficult for F1 power unit suppliers to adapt, and most likely much simpler to get it working well than the MGUH, which the current 4 suppliers have mastered.

I used the front wheel example because it has lower fuel usage and higher recovery, which would be more applicable to an EV.

[Just_a_fan]

I doubt it had anything to do with Audi, but rather weight and cost, since the chassis would have to be completely redesigned.

Yes, weight has been mentioned by some sources. I saw 30kg mentioned somewhere to add a front generator, drive shafts and wiring. Of course, adding 30kg at the front to ensure the battery can be fully charged under braking might also mean a bit less fuel weight - it changes the balance a bit, admittedly, but not necessarily a terrible thing.

I quite like the idea of front regen - allow more regen and let the teams decide how they want to mix fuel and battery power systems.

[Zynerji]

I doubt it had anything to do with Audi, but rather weight and cost, since the chassis would have to be completely redesigned.

Yes, weight has been mentioned by some sources. I saw 30kg mentioned somewhere to add a front generator, drive shafts and wiring. Of course, adding 30kg at the front to ensure the battery can be fully charged under braking might also mean a bit less fuel weight - it changes the balance a bit, admittedly, but not necessarily a terrible thing.

I quite like the idea of front regen - allow more regen and let the teams decide how they want to mix fuel and battery power systems.

Honda had a front diff in their 2008 car. Seems like front regen wouldn't need much after that...

[mzso]

Ok. Seems like it wouldn't be beyond reason that they could engineer a superfluid to exchange. I'm not sure why swapping just the inside of the battery instead of the entire battery is so offensive to you.

What's a "superfluid"?
In any ways. Pooring in a fluid, then getting it to react with oxygen from the air is better in every way. So why bother with weird liquid electrodes?

[mzso]

We were talking 2035, and F1 sticking with ICE+ERS until then. Which is in no way set in stone, unlike you claims.

No it is not certain.

It may move towards ICE only, or to full electric.

Or the 2026 PU rules may last 7until 2040. Who knows what the future will bring.

That'd be odd. The car industry is set out to be very different by 2040.

[Zynerji]

Ok. Seems like it wouldn't be beyond reason that they could engineer a superfluid to exchange. I'm not sure why swapping just the inside of the battery instead of the entire battery is so offensive to you.

What's a "superfluid"?
In any ways. Pooring in a fluid, then getting it to react with oxygen from the air is better in every way. So why bother with weird liquid electrodes?

Like the Zinc-Air batteries that you use in your hearing aid?

They have a superfluid gel for that!

https://www.sciencedirect.com/science/a ... 4722047805

[wuzak]

We were talking 2035, and F1 sticking with ICE+ERS until then. Which is in no way set in stone, unlike you claims.

No it is not certain.

It may move towards ICE only, or to full electric.

Or the 2026 PU rules may last 7until 2040. Who knows what the future will bring.

That'd be odd. The car industry is set out to be very different by 2040.

It may be, but the idea that F1 should have any reflection on the car industry is relatively new.

It is likely than there will still be more ICE vehicles than EVs in 2040, even if new ICE vehicles are not allowed to be sold.

[Zynerji]

No it is not certain.

It may move towards ICE only, or to full electric.

Or the 2026 PU rules may last 7until 2040. Who knows what the future will bring.

That'd be odd. The car industry is set out to be very different by 2040.

It may be, but the idea that F1 should have any reflection on the car industry is relatively new.

It is likely than there will still be more ICE vehicles than EVs in 2040, even if new ICE vehicles are not allowed to be sold.

We have the most road-relevant tech being removed for 2026...RIP MGUH

[mzso]

No it is not certain.

It may move towards ICE only, or to full electric.

Or the 2026 PU rules may last 7until 2040. Who knows what the future will bring.

That'd be odd. The car industry is set out to be very different by 2040.

It may be, but the idea that F1 should have any reflection on the car industry is relatively new.

It is likely than there will still be more ICE vehicles than EVs in 2040, even if new ICE vehicles are not allowed to be sold.

Perhaps. But stuff that's no-one's actively using was never a part of F1.

[PlatinumZealot]

Some rough calcs.

Current Cars.
Fuel allowed per race: 110kg
Fuel energy density: ~45MJ/kg
Potential Fuel Energy per race: 4950MJ
Assuming 50% efficiency, the actual energy used to propel the car is 2475MJ = 687.5kWh

2026 Cars.
Fuel allowed per race: 70kg*
Fuel energy density: ~40MJ/kg (between 38 and 41 MJ/kg allowed)
Potential Fuel Energy per race: 2800MJ
Assuming 50% efficiency, the actual energy used to propel the car is 1400MJ = 388.9kWh

* From statements by Pat Symonds that the 2026 cars could do a race with 70kg of fuel if front wheel recovery is used.


Assuming efficiency of 90% for an EV to convert battery to motion, that would require storage of:
763.9kWh based on 2023 cars and performance.
432kWh based on projected 2026 car and performance.

Hot swapping batteries would require 8 or 9 Formula E batteries and 7 or 8 swaps per race to get equivalent performance to the 2026 car.

If we take the upper energy density of future solid state batteries per the chart posted by PlatinumZealot, 500Wh/kg, the battery size would need to be at least 864kg. And that would be the cells only.

The 2026 cars are to have an ICE of 130kg plus a 350kW motor of 20kg (16kg plus 4kg for gearbox) and 35kg (minimum) battery enclosure (includes more than just cells). Less than 300kg when the fuel is included.

Your calculation is flawed though. Not trying to break you leg or anything.

You missed out on the brake regen calculations even though you mentioned it.

Current cars... fuel usage - 95kg, fuel LHV 43MJ/kg = 4950MJ. Thermal efficiency with MGUH ~ 52% = 2,124MJ energy input.

Rear brake recovery ~3MJ per lap average (use 50 lap race) = 150MJ
"Energy to speed, net" = 1974MJ

Increase brake recovery for 2026. Increase rear brake to double harvest = 300MJ. Front brake energy recovery is very heavy machinery, as we see in LMP cars... but I will allow it.. Front brake recovery = 600MJ per race.
Total brake recovery = 900MJ per race.

New cars 2026 fuel weight = 70kg >> 41M/kg = 2,870 MJ. Thermal efficiency with loss of MGUH ~ 45% >> 1,291.5MJ. ( a drop of 800MJ or roughly 40% energy drop.
"Energy to speed deficit" = (2124 - 1291) + (150 - 900) = 83MJ

You need 83MJ more energy to make up for the loss of fuel, if we assume that more brake energy currently lost as heat is recovered at twice the amount on the rear, and a matching, proportional amount on the front (to keep brake balance in line). This is 23kWhrs.


Add in the hypothetical 90% round trip efficiency of the MGUK, that's about 25kWhrs of additional battery.

Basically a second Formula 1 battery. Remember I also allowed for increases in energy density of the batteries the weight might not be double the current battery.

This is very close to coinciding with my prior assumptions. And it should make sense because we are not using mickey mouse numbers, but reasonable assumptions.

[PlatinumZealot]

2026 Cars.
Fuel allowed per race: 70kg*
Fuel energy density: ~40MJ/kg (between 38 and 41 MJ/kg allowed)
Potential Fuel Energy per race: 2800MJ
Assuming 50% efficiency, the actual energy used to propel the car is 1400MJ = 388.9kWh

* From statements by Pat Symonds that the 2026 cars could do a race with 70kg of fuel if front wheel recovery is used.

Front wheel recovery has been been vetoed by the teams, hasn't it? Something to do with worrying that Audi will be much better at it than the rest thanks to experience elsewhere.

Wow? really?! This is big news! And basically kills any idea of increased electrification if you ask me. I will be watching keenly how they work around this.

[wuzak]

You missed out on the brake regen calculations even though you mentioned it.

I think brake energy recovery is included in the fuel usage.

Less brake recovery, more fuel usage.

Rear brake recovery ~3MJ per lap average (use 50 lap race) = 150MJ
"Energy to speed, net" = 1974MJ

Rear brake recovery is less than 2MJ/lap in current PUs. Some tracks it is around 1MJ.

What is "energy to speed, net"?

Increase brake recovery for 2026. Increase rear brake to double harvest = 300MJ. Front brake energy recovery is very heavy machinery, as we see in LMP cars... but I will allow it.. Front brake recovery = 600MJ per race.
Total brake recovery = 900MJ per race.

The limit for recovery for 2026 is 9MJ. But since we are talking using harvesting from braking only.

The average braking per lap, over the season, is ~15s.
The power of the MGUK for recovery is 350kW.
That gives an average energy recovery per lap of 5.25MJ.
Or, for a 50 lap race, a total of 262.5MJ.

Compared to 1,400MJ used to propel the car from the fuel.

New cars 2026 fuel weight = 70kg >> 41M/kg = 2,870 MJ. Thermal efficiency with loss of MGUH ~ 45% >> 1,291.5MJ. ( a drop of 800MJ or roughly 40% energy drop.
"Energy to speed deficit" = (2124 - 1291) + (150 - 900) = 83MJ

Thermal efficiency was projected to be ~48%, giving projected 400kW power output of ICE.

You need 83MJ more energy to make up for the loss of fuel, if we assume that more brake energy currently lost as heat is recovered at twice the amount on the rear, and a matching, proportional amount on the front (to keep brake balance in line). This is 23kWhrs.

Front recovery has been disallowed.

In any case, it isn't likely that the energy recovery would be significantly more, since a proposed recovery system with front and rear MGUs had, more or less, the same power as the 2026 regulations.

Add in the hypothetical 90% round trip efficiency of the MGUK, that's about 25kWhrs of additional battery.

Basically a second Formula 1 battery. Remember I also allowed for increases in energy density of the batteries the weight might not be double the current battery.

This is very close to coinciding with my prior assumptions. And it should make sense because we are not using mickey mouse numbers, but reasonable assumptions.

A current F1 battery is allowed 4MJ storage (1.1kWh).

Based on a chart you posted earlier in the thread, lithium-ion batteries have an energy density of between 100Wh/kg and 275Wh/kg. Let's be generous and say that F1 ES has 300Wh/kg energy density.

The weight of the current ES is between 20kg and 25kg, as specified by the rules. This includes the cells, clamping plates and cell connections.

So that would be a total energy storage of 300Wh/kg * 25kg = 7.5kWh.

Your theoretical 25kWh difference would require an additional 4 batteries.


In any case, the loss of fuel energy will be compensated by the reduction in drag from the 2026 chassis, not through the increase in electrification.

My calculations were for a full EV F1 car.

To me that is the only scenario where swappable batteries would be contemplated.

[mzso]

Front recovery has been disallowed.

In any case, it isn't likely that the energy recovery would be significantly more, since a proposed recovery system with front and rear MGUs had, more or less, the same power as the 2026 regulations.

You mean other than the fact that it's guaranteed to be more than double? Front wheels do most of the braking of course, and right now they exclusively use all that energy to heat up the brake disk to glowing red/orange.

[Tommy Cookers]

....the loss of fuel energy will be compensated by the reduction in drag from the 2026 chassis ....

how wouldn't this cause a reduction in aerodynamic downforce ? .....
reducing tyre grip and braking force available .....
disproportionately increasing the time for regeneration (at 350 kW) before the grip further reduces .....

this would be a big part of filling the 'energy-gap'

[PlatinumZealot]

@Wuzak. There is no limit on F1 battery storage. The weight is limited and the discharge per lap.

You cannot ignore the brake recovery if you want to look at the energy input from the fuel. It's straiyht forward that more brake recovery means you can, use that energy from the battery and make do with less fuel.

My calculation accounts for the brake energy used to make the lesser fuel stretch as much as possible over the race, and the deficit is to be filled in by an additional battery usage.