2026 active aero discussions

[wuzak]

2026+ batteries will weigh too much due to el./ICE power ratio, so that's a big hurdle for weight reduction.

The Energy Store has a specified minimum weight of 35kg for 2026.

The current ES has a minimum weight of 31kg.

The extra is probably to handle the higher power flows.

The ES has the same restrictions as now - maximum 4MJ difference between maximum and minimum charge, though 9MJ can be recovered and unlimited energy deployed.

[wuzak]

DO you think that they haven't released any details of the 2026 aero rules because they are having trouble making them work with the 2026 PU to give good lap times?

[Holm86]

DO you think that they haven't released any details of the 2026 aero rules because they are having trouble making them work with the 2026 PU to give good lap times?

Perhaps it's part of it, but usually aero regulations get finalised much later than engine regulations. I wouldn't expect to see 2026 regulations till mid to late 2024

[Vanja #66]

The Energy Store has a specified minimum weight of 35kg for 2026.

The current ES has a minimum weight of 31kg.

The extra is probably to handle the higher power flows.

The ES has the same restrictions as now - maximum 4MJ difference between maximum and minimum charge, though 9MJ can be recovered and unlimited energy deployed.

Ah, thanks, so better recovery is allowed. I like that, gives me even more hope for another good step with 2026 rules.

[wuzak]

The Energy Store has a specified minimum weight of 35kg for 2026.

The current ES has a minimum weight of 31kg.

The extra is probably to handle the higher power flows.

The ES has the same restrictions as now - maximum 4MJ difference between maximum and minimum charge, though 9MJ can be recovered and unlimited energy deployed.

Ah, thanks, so better recovery is allowed. I like that, gives me even more hope for another good step with 2026 rules.

Still can only store 4MJ.

[AR3-GP]

The Energy Store has a specified minimum weight of 35kg for 2026.

The current ES has a minimum weight of 31kg.

The extra is probably to handle the higher power flows.

The ES has the same restrictions as now - maximum 4MJ difference between maximum and minimum charge, though 9MJ can be recovered and unlimited energy deployed.

Ah, thanks, so better recovery is allowed. I like that, gives me even more hope for another good step with 2026 rules.

Still can only store 4MJ.

You can hold more than 4MJ. The difference in state of charge just can't exceed that.

[Stu]

Considering that battery life is important (limited number of units per season) a total battery store capacity of approximately 6MJ would be sensible (depending on C rating) allowing the battery to be maintained between 20-80% capacity.

[henry]

Considering that battery life is important (limited number of units per season) a total battery store capacity of approximately 6MJ would be sensible (depending on C rating) allowing the battery to be maintained between 20-80% capacity.

I think it needs to be larger to allow for losses. With 2MJ cycled through the ES each lap and 98% round trip efficiency, over 50 laps there will b e 2MJ loss. This means the difference between max ES level at race start and min at race end could be 6MJ.

[AR3-GP]

Considering that battery life is important (limited number of units per season) a total battery store capacity of approximately 6MJ would be sensible (depending on C rating) allowing the battery to be maintained between 20-80% capacity.

I think it needs to be larger to allow for losses. With 2MJ cycled through the ES each lap and 98% round trip efficiency, over 50 laps there will b e 2MJ loss. This means the difference between max ES level at race start and min at race end could be 6MJ.

Are you suggesting a 2MJ capacity fade in 1 race? The teams only are allowed 2-3 ES per season. If what you say is correct, it would not be manageable.

The efficiency should consider how much of the energy you put into the battery, is able to come back out (losses can occur due to side reactions which consume electrons or otherwise de-activate the active material (capacity fade) and internal resistance which dissipates some of the electrical energy as thermal energy (joule heating).

The capacity fade over a race is not 2MJ simply because they'd never finish a season on 2-3 ES if so. So I can only presume this 98% figure references the joule heating. In that case, you don't need to "compensate" by building a bigger battery.

The battery only needs to be large enough to account for capacity fade (which is definetely not on the order of 2% per lap). It will have to be significantly smaller since teams run 2-3 ES per season.

[wogx]

BTW that topic turned "off" a long time ago

[henry]

Considering that battery life is important (limited number of units per season) a total battery store capacity of approximately 6MJ would be sensible (depending on C rating) allowing the battery to be maintained between 20-80% capacity.

I think it needs to be larger to allow for losses. With 2MJ cycled through the ES each lap and 98% round trip efficiency, over 50 laps there will b e 2MJ loss. This means the difference between max ES level at race start and min at race end could be 6MJ.

Are you suggesting a 2MJ capacity fade in 1 race? The teams only are allowed 2-3 ES per season. If what you say is correct, it would not be manageable.

The efficiency should consider how much of the energy you put into the battery, is able to come back out (losses can occur due to side reactions which consume electrons or otherwise de-activate the active material (capacity fade) and internal resistance which dissipates some of the electrical energy as thermal energy (joule heating).

The capacity fade over a race is not 2MJ simply because they'd never finish a season on 2-3 ES if so. So I can only presume this 98% figure references the joule heating. In that case, you don't need to "compensate" by building a bigger battery.

The battery only needs to be large enough to account for capacity fade (which is definetely not on the order of 2% per lap). It will have to be significantly smaller since teams run 2-3 ES per season.

You are right. I’m not saying the battery loses capacity, I’m saying that the energy level in the battery goes down during the race. It leaks. The energy management measurements happen outside the battery. So the 4MJ SOC refers to the integral of energy going into and leaving the battery management system.

And you’re right there is heating. The C rates are relatively high. If we assume an 8MJ battery and 120kW charge and discharge that’s around a C of 5 for most of the time the ES is in use. At times the charge and discharge rates are as high as 200kW. 98% efficiency at these C rates is quite generous, but I assume these are state of the art and better than run of the mill commercial devices.

So yes you need to compensate by having a battery that is bigger by the amount of MJ loss you expect over a race.

Edit: for most of a lap
the discharge rate is only about 40 to 50 kW so the c rate is rather lower. So 98% isn’t such a stretch.

[AR3-GP]

I think it needs to be larger to allow for losses. With 2MJ cycled through the ES each lap and 98% round trip efficiency, over 50 laps there will b e 2MJ loss. This means the difference between max ES level at race start and min at race end could be 6MJ.

Are you suggesting a 2MJ capacity fade in 1 race? The teams only are allowed 2-3 ES per season. If what you say is correct, it would not be manageable.

The efficiency should consider how much of the energy you put into the battery, is able to come back out (losses can occur due to side reactions which consume electrons or otherwise de-activate the active material (capacity fade) and internal resistance which dissipates some of the electrical energy as thermal energy (joule heating).

The capacity fade over a race is not 2MJ simply because they'd never finish a season on 2-3 ES if so. So I can only presume this 98% figure references the joule heating. In that case, you don't need to "compensate" by building a bigger battery.

The battery only needs to be large enough to account for capacity fade (which is definetely not on the order of 2% per lap). It will have to be significantly smaller since teams run 2-3 ES per season.

You are right. I’m not saying the battery loses capacity, I’m saying that the energy level in the battery goes down during the race. It leaks. The energy management measurements happen outside the battery. So the 4MJ SOC refers to the integral of energy going into and leaving the battery management system.

And you’re right there is heating. The C rates are relatively high. If we assume an 8MJ battery and 120kW charge and discharge that’s around a C of 5 for most of the time the ES is in use. At times the charge and discharge rates are as high as 200kW. 98% efficiency at these C rates is quite generous, but I assume these are state of the art and better than run of the mill commercial devices.

So yes you need to compensate by having a battery that is bigger by the amount of MJ loss you expect over a race.

I don't understand what you are trying to say. The only thing the teams need to account for is capacity fade. This 98% number that you mention has no bearing. The joule heating losses are not recoverable. You cannot compensate them by "building a bigger battery" (atleast not in a direct fashion. A bigger battery has the side effect of reducing the current density and C-rate, and thus the joule heating losses are smaller, but this is a secondary effect).

It doesn't matter if some energy "leaks" because in this case the "energy" leakage you refer to is electrons, not the physical material of the battery (for the most part). Electrons are "free" and the battery can be refilled by the MGU-K and MGU-H in so much as the braking and fuel energy allows.

You are thinking of a picture like a bucket of water that has a leak. You want to travel across the desert and you know you are leaking 1 gallong per hour so you start with 2 gallons of water instead of 1 gallon of water to compensate so you can drink 1 gallon on the 1 hour trip.

A battery is not like this. The MGU-K and MGU-H "Create new water" (please excuse the Newton's law violation ). They create as much new water as you need to restore 4MJ of energy for usage in the lap. I think this is the difference between what you are imagining, and the actual battery.

This 98% roundtrip efficiency is only compensated by working the MGU-K and MGU-H harder within the upperlimit of the braking and fuel energy available. It's not compensated by using a larger battery.

[wuzak]

Ah, thanks, so better recovery is allowed. I like that, gives me even more hope for another good step with 2026 rules.

Still can only store 4MJ.

You can hold more than 4MJ. The difference in state of charge just can't exceed that.

Yes, that's what I meant.

It is the effective storage.

While the 2026 rules allow for 9MJ of recovery, only 4MJ can be stored at any time.

[henry]

Are you suggesting a 2MJ capacity fade in 1 race? The teams only are allowed 2-3 ES per season. If what you say is correct, it would not be manageable.

The efficiency should consider how much of the energy you put into the battery, is able to come back out (losses can occur due to side reactions which consume electrons or otherwise de-activate the active material (capacity fade) and internal resistance which dissipates some of the electrical energy as thermal energy (joule heating).

The capacity fade over a race is not 2MJ simply because they'd never finish a season on 2-3 ES if so. So I can only presume this 98% figure references the joule heating. In that case, you don't need to "compensate" by building a bigger battery.

The battery only needs to be large enough to account for capacity fade (which is definetely not on the order of 2% per lap). It will have to be significantly smaller since teams run 2-3 ES per season.

You are right. I’m not saying the battery loses capacity, I’m saying that the energy level in the battery goes down during the race. It leaks. The energy management measurements happen outside the battery. So the 4MJ SOC refers to the integral of energy going into and leaving the battery management system.

And you’re right there is heating. The C rates are relatively high. If we assume an 8MJ battery and 120kW charge and discharge that’s around a C of 5 for most of the time the ES is in use. At times the charge and discharge rates are as high as 200kW. 98% efficiency at these C rates is quite generous, but I assume these are state of the art and better than run of the mill commercial devices.

So yes you need to compensate by having a battery that is bigger by the amount of MJ loss you expect over a race.

I don't understand what you are trying to say. The only thing the teams need to account for is capacity fade. This 98% number that you mention has no bearing. The joule heating losses are not recoverable. You cannot compensate them by "building a bigger battery" (atleast not in a direct fashion. A bigger battery has the side effect of reducing the current density and C-rate, and thus the joule heating losses are smaller, but this is a secondary effect).

It doesn't matter if some energy "leaks" because in this case the "energy" leakage you refer to is electrons, not the physical material of the battery (for the most part). Electrons are "free" and the battery can be refilled by the MGU-K and MGU-H in so much as the braking and fuel energy allows.

You are thinking of a picture like a bucket of water that has a leak. You want to travel across the desert and you know you are leaking 1 gallong per hour so you start with 2 gallons of water instead of 1 gallon of water to compensate so you can drink 1 gallon on the 1 hour trip.

A battery is not like this. The MGU-K and MGU-H "Create new water" (please excuse the Newton's law violation ). They create as much new water as you need to restore 4MJ of energy for usage in the lap. I think this is the difference between what you are imagining, and the actual battery.

This 98% roundtrip efficiency is only compensated by working the MGU-K and MGU-H harder within the upperlimit of the braking and fuel energy available. It's not compensated by using a larger battery.

I was responding to @Stu’s estimation of how to size the battery. The “leak” is not compensated for by the K and H. The leak happens in the battery but the SOC is measured outside the battery and so can be compensated for by energy stored before the race begins.

While the SOC variation is fixed at 4MJ the maximum battery capacity change is SOC + leakage, 6MJ in my example. So to operate between 20 and 80% the battery capacity would need to be 6/.6, 10MJ.

Since we’re way off topic I’ll mention also that even though the 2026 regs have the same SOC requirement the battery capacity will likely be higher because the typical C rate will be much higher leading to higher losses during the race. The 2026 regs expect the ES to be heavier even though SOC is the same which supports this rationale.

[wuzak]

I was responding to @Stu’s estimation of how to size the battery. The “leak” is not compensated for by the K and H. The leak happens in the battery but the SOC is measured outside the battery and so can be compensated for by energy stored before the race begins.

While the SOC variation is fixed at 4MJ the maximum battery capacity change is SOC + leakage, 6MJ in my example. So to operate between 20 and 80% the battery capacity would need to be 6/.6, 10MJ.

Since we’re way off topic I’ll mention also that even though the 2026 regs have the same SOC requirement the battery capacity will likely be higher because the typical C rate will be much higher leading to higher losses during the race. The 2026 regs expect the ES to be heavier even though SOC is the same which supports this rationale.

5.4.8 The difference between the maximum and the minimum state of charge of the ES may not exceed 4MJ at any time the car is on the track.

To me that means the minimum o r maximum state of charge at any time of a race or practice session.

So you can't have min to max of 2MJ and 6MJ one lap and 1.5MJ and 5.5MJ on another lap.