2025/2026 Hybrid Powerunit speculation

[gruntguru]

I've mentioned battery size and Amps as a general relation, 2026 PU will be limited to 1000V, so the peak current won't be lower than 350A. C rate depends on battery capacity (Ah), which is the parameter teams can play with. 4MJ is only 1111Wh of capacity, which can be achieved with 4-5kg of LiPo batteries. ES has to be at least 35kg (with casing and everything) so batteries can be oversized for bigger capacity and lower C rate.

I guess we can assume batteries will have around 6kWh (25-30kg of LiPo cells in this case) capacity to keep it round and simple, so at 1000V max capacity (for a LiHV cell) that's 4.3V per cell, ie 232 theoretical cells and that's working voltage of 858V - meaning 7Ah of batteries. At 408A (350kW at 858V), you have a C rate of 58C which is quite ok, there are cells that can go over 100C. So if you reduce capacity to 3kWh you are at 115C and if you drop to 2kWh you are already at 175C which is usually too high.

If you limit your LiPo cells to their nominal voltage of 3.7V and settle for 270 theoretical cells to reach maximal=nominal 1000V, you are "down" to 6Ah capacity, but your current is now also "down" to 350A and this keeps C rate at 58C of course. Lower current means less heat and higher number of cells means closer Voltage between min and max SOC for each cell and in this case cells will practically stay around 3.7V the whole time since you are only using 1.1Ah of 6Ah of capacity. This will also extend their working life a lot, compared to having them go from 4.2V to 3.2V and back 2-3 times a lap.

Does anyone know how the 1000V limit is defined? If it is the highest voltage anywhere in the system at any time you would definitely have to limit the number of series cells - to 1000/4.35V (the maximum charging voltage of a LiHV cell) = 230 series cells.

OTOH 1000V might be the maximum operating voltage of the MGUK, in which case higher voltages might be possible in the ES and therefore a higher cell count.

[mzso]

But what you're saying there makes zero sense, why on earth would you have a 44MJ battery if in could never go under 40MJ in that case.

The battery will probably have a minimum charge of perhaps 0.5MJ which means the maximum charge capacity probably won't be over 5MJ as the maximum state can only ever go 4MJ over the minimum, you need a bit og leeway

And as I said, the current regulations say exactly the same as those of 2026 when it comes to the delta charge of the battery, so why would it need to be bigger

Because ES needs to last a long time. Today they should live through 12 race weekends, meaning at least 7500-8000km of hard and constant use. By making an oversized battery you reduce the current (Amps) and thus the charge/discharge rate (aka C-rate) which needs to be kept low for long battery life.

How does battery size influence amps?
And C rate will just increase as battery size does, all other aspects kept the same.
I know there need to be some overhead, as a battery charges faster at the lower end of its capacity.
If you want to lower amps, you need to raise the voltage.
Only thing I can't think off is if internal resistance of the battery lowers as capacity increases, but it shouldn't be so much that I can't be overcome with higher voltage

The battery cell voltage is a given, voltage cannot be raised. Current being manipulated after taken from the cells, does not concern the cells. If you want to be easier on the cells, you need to increase the number of them, which means increasing the battery capacity. More cells will have a lighter current load and last longer, and will be used more efficiently as well.

[mzso]

Does anyone know how the 1000V limit is defined? If it is the highest voltage anywhere in the system at any time you would definitely have to limit the number of series cells - to 1000/4.35V (the maximum charging voltage of a LiHV cell) = 230 series cells.

OTOH 1000V might be the maximum operating voltage of the MGUK, in which case higher voltages might be possible in the ES and therefore a higher cell count.

Is there a limit? I always thought it's just a decision by teams to go for 1000V from lower voltage systems. I don't remember any specified limit.
I don't think the cells are a factor in this voltage. You feed whatever to the power electronics and 1000V comes out.
Not sure why they do this though. It's the current running through the windings what drives motors, no matter how much voltage was needed to create it. Just to save weight on wires connecting parts?

[Tommy Cookers]

Is there a limit? I always thought it's just a decision by teams to go for 1000V from lower voltage systems. I don't remember any specified limit.
I don't think the cells are a factor in this voltage. You feed whatever to the power electronics and 1000V comes out.
Not sure why they do this though. It's the current running through the windings what drives motors, no matter how much voltage was needed to create it. Just to save weight on wires connecting parts?

that's the opposite of what you said last year !
(ok the year before last)

[Vanja #66]

Does anyone know how the 1000V limit is defined? If it is the highest voltage anywhere in the system at any time you would definitely have to limit the number of series cells - to 1000/4.35V (the maximum charging voltage of a LiHV cell) = 230 series cells.

OTOH 1000V might be the maximum operating voltage of the MGUK, in which case higher voltages might be possible in the ES and therefore a higher cell count.

It's maximum working voltage as per 5.19.6 --> https://www.fia.com/sites/default/files ... 6-11_1.pdf

Battery chemistry isn't regulated afaik, so manufacturers are free to do what they want with cells. I still think they'll want to avoid charging cells fully, eg LiPos will last much longer if kept between 3.8-3.6V

[mzso]

Is there a limit? I always thought it's just a decision by teams to go for 1000V from lower voltage systems. I don't remember any specified limit.
I don't think the cells are a factor in this voltage. You feed whatever to the power electronics and 1000V comes out.
Not sure why they do this though. It's the current running through the windings what drives motors, no matter how much voltage was needed to create it. Just to save weight on wires connecting parts?

that's the opposite of what you said last year !
(ok the year before last)

Uh, what do you mean?

[Holm86]

Because ES needs to last a long time. Today they should live through 12 race weekends, meaning at least 7500-8000km of hard and constant use. By making an oversized battery you reduce the current (Amps) and thus the charge/discharge rate (aka C-rate) which needs to be kept low for long battery life.

How does battery size influence amps?
And C rate will just increase as battery size does, all other aspects kept the same.
I know there need to be some overhead, as a battery charges faster at the lower end of its capacity.
If you want to lower amps, you need to raise the voltage.
Only thing I can't think off is if internal resistance of the battery lowers as capacity increases, but it shouldn't be so much that I can't be overcome with higher voltage

The battery cell voltage is a given, voltage cannot be raised. Current being manipulated after taken from the cells, does not concern the cells. If you want to be easier on the cells, you need to increase the number of them, which means increasing the battery capacity. More cells will have a lighter current load and last longer, and will be used more efficiently as well.

Makes sense

[wuzak]

2026 PUs are going to reach 1100 HP according to Tombazis

https://www.racefans.net/2024/06/12/for ... s-in-2026/

Mark Hughes was reporting 450kW ICE almost a year ago:

At the current level of technology we are looking at power units with a total of around 1100bhp or 800Kw (split 450Kw/350Kw between engine and battery) which will suddenly be bereft of the battery’s 350kw contribution somewhere on the lap.

https://www.motorsportmagazine.com/arti ... e-a-point/

Maybe his source was Tombazis?

[bananapeel23]

So what is the chance of the fuel flow being raised a bit to help these anemic ICEs out?

Do you think it's at all likely that we end up seeing 80kg/h (whatever that is in MJ).

[Cold Fussion]

2026 PUs are going to reach 1100 HP according to Tombazis

https://www.racefans.net/2024/06/12/for ... s-in-2026/

A copy of my post from the 2026 chassis thread.

1,100hp = 820kW

MGUK power = 350kW

Which means ICE power = 470kW

Which is much more than the originally expected 400kW, and makes it even less 50/50 between ICE and MGUK.

Maximum fuel flow is 3,000MJ/h = 833kW

Which means that the ICE efficiency would be ~56%.

Which would be quite astounding.

If that was truly the case, they could reduce the MGUK output power to 250kW, which would give maximum power of 965hp. But it would make the energy last longer.

How feasible is it that they really are going to be hitting 56%, especially with the removal of the MGU-H? It sounds unbelievably high.

[FW17]

2026 PUs are going to reach 1100 HP according to Tombazis

https://www.racefans.net/2024/06/12/for ... s-in-2026/

A copy of my post from the 2026 chassis thread.

1,100hp = 820kW

MGUK power = 350kW

Which means ICE power = 470kW

Which is much more than the originally expected 400kW, and makes it even less 50/50 between ICE and MGUK.

Maximum fuel flow is 3,000MJ/h = 833kW

Which means that the ICE efficiency would be ~56%.

Which would be quite astounding.

If that was truly the case, they could reduce the MGUK output power to 250kW, which would give maximum power of 965hp. But it would make the energy last longer.

How feasible is it that they really are going to be hitting 56%, especially with the removal of the MGU-H? It sounds unbelievably high.

Wasn't the reported 50% efficiency of the current engines achieved when the compressor side was run as a supercharger with MGU-H and the turbine side running with the wastegates open?

[Cold Fussion]

Wasn't the reported 50% efficiency of the current engines achieved when the compressor side was run as a supercharger with MGU-H and the turbine side running with the wastegates open?

I've always thought the above 50% figures were the ICE + MGU-H recovery.

[Hoffman900]

I’ve seen the same engine make 150hp difference depending on the dyno.

Never believe advertised numbers, especially from OEM racing programs.

I have never doubted a power claim from an F1 team. (and they use accurate dynos)

Like Renault’s 1000hp claim a few years ago?

[wuzak]

Wasn't the reported 50% efficiency of the current engines achieved when the compressor side was run as a supercharger with MGU-H and the turbine side running with the wastegates open?

I've always thought the above 50% figures were the ICE + MGU-H recovery.

I would think that the peak efficiency was achieved with the MGUH and MGUK working in a turbo-compound mode.

That is, the recovered energy from the MGUH directly drives the MGUK and no energy is transferred to or from the battery.

When the MGUH is driving the turbo it is taking energy from the battery. Therefore using more energy than can be extracted from the fuel.

[FW17]

I would think that the peak efficiency was achieved with the MGUH and MGUK working in a turbo-compound mode.

That is, the recovered energy from the MGUH directly drives the MGUK and no energy is transferred to or from the battery.

When the MGUH is driving the turbo it is taking energy from the battery. Therefore using more energy than can be extracted from the fuel.

That is a good mode, but that is not the maximum power to the wheels.

Assuming 1000hp in total in qualifying
160 hp comes from MGUK
840 hp comes from ICE with battery powering the MGUH to drive the compressor and turbines running with waste gates open
840 hp is 620 kw which is 50% of available energy from 100 kg of fuel