How to simplify the complex subject of F1's electrical rules

I have had countless questions from readers and indeed even those in the sport about the complications of energy management. An example is reader Ian Woodcock’s question about how drivers maintain high throttle openings in corners to recharge the battery. The reality is that most of the energy management is automatic, but so complex that it has been very easy for the drivers to get caught out by small changes in the way they drive.

A full explanation of the energy management is perhaps beyond the scope of a short article and extremely difficult to explain in detail, but perhaps a bit of simplification and history may go some way to answering those questions.

Firstly, we need to get some basics out of the way. Much has been said about Formula 1’s 50/50 split of power between the engine and the electrical system. This is roughly true: the engine produces a little over 540bhp and the electrical system is capped at 470bhp, so 53.5/46.5 to be pedantic. However, this is not the root of the problem. 

While the power split may be roughly equal, the energy split is far from it. A typical lap might use 1.7kg of fuel and from this, at the crankshaft we may obtain 32 megajoules (MJ) of energy.

When you drive somewhere in your car you don’t think what your average power per mile was, you think what the average fuel consumption (or battery consumption if you are in an EV) was

The electrical energy we have available is derived from energy recovery under braking when the electric motor operates like an alternator to charge the battery and also when we are allowing the engine, via the electric motor, to charge the battery even when not braking. The total energy that can be recovered in these two methods is limited by regulation. The first regulation of concern is one that says that the total energy in the battery cannot change by more than 4MJ. 

Perhaps we should explain what a megajoule is. We are all accustomed to expressing energy in kilowatt hours (kWh). This is how our electricity is charged and even electric vehicles quote their ‘fuel consumption’ in terms of kWh per 100 kilometres. A megajoule is just another unit for energy and one more favoured by engineers. A megajoule is just over a quarter of a kilowatt hour.

So, we can’t change the state of charge of the battery by more than 4MJ and we are also regulated circuit to circuit as to what the maximum recharge allowed is. This has been typically 8MJ. So if we want to keep the battery in a neutral state, as we would on a normal race lap, we can only deploy 8MJ of electrical energy. 

In qualifying, if we had the same recharge allowance (it is sometimes a bit more and sometimes a bit less), we could deploy this in addition to the 4MJ that we can take from the battery, so 12MJ total. Remembering that we are obtaining 32MJ of energy from the fuel, we see that the energy split, which is actually more important than the power split, is more like 73/27. Think of it this way – when you drive somewhere in your car you don’t think what your average power per mile was, you think what the average fuel consumption (or battery consumption if you are in an EV) was. In other words, the average energy that you used.

The supposed 50/50 power split does not tell the full story, nor is it at the root of the problem

Photo by: Honda

When it was decided that the MGU-H, the very efficient generator on the turbocharger, would not be part of the 2026 regulations, the plan was to replace this lost energy source with front wheel energy recovery. This could have been sized so that even with the so called 50/50 power split, the system would not be anywhere near as energy sparse as it is today. Unfortunately, this was regarded as a red line by one manufacturer and therefore it was dropped, which led directly to the problems the teams now have.

Recently a lot of work has been put into how the situation may be improved. The changes implemented since the Japanese GP are a reasonable step forward, so let’s try to explain some of them. Firstly, the power available to recover energy in the so-called ‘super clip’ has been increased.

Remember from your school physics that energy is power multiplied by time. Therefore, the increase of super clip power from 250kW to 350kW means that, for a given amount of energy, the time spent in this condition where the engine is driving the car at the end of the straight but most of its power is being used to charge the battery will reduce. 

Perhaps more significantly, it will no longer be possible to deploy 350kW from the electric motor on all straights. Some will be limited to 250kW, which will make a significant difference to the amount of energy required with just a small change to lap time. It is perhaps not obvious without knowledge of the regulations that the electrical power deployment is not constant. It reduces as the car goes down the straight in a staircase fashion at either 100kW or 50kW per second depending on the circuit. As well as this, there is a further limit that kicks in at high speed.

The drivers found it very difficult to balance getting enough speed as they crossed the timing line at the beginning of a timed lap with the need to also start the lap with a fully charged battery

Considering the importance of maximising electrical energy use on a qualifying lap, the drivers found it very difficult to balance getting enough speed as they crossed the timing line at the beginning of a timed lap with the need to also start the lap with a fully charged battery. A change has been made that now allows the staircasing to be reset before the timing line, meaning drivers don’t have to juggle with the throttle before starting a qualifying lap. Equally, the engineers can now set the system more easily to make sure all the allowable battery energy is used by the end of the lap.

Two more functions that have not been explained are ‘boost’ and ‘overtake’. Overtake is the electrical equivalent of DRS. When a car is less than one second behind a competitor, the driver can select an overtake mode that gives full electrical power as well as an additional ration of energy in order to make an overtaking manoeuvre.

Boost can be used at any time and will hold the electrical power at its current level or 150kW, whichever is greater. The big difference to overtake is that no additional recharge energy is allowed, which leads to a ‘robbing Peter to pay Paul’ situation. The driver feels the loss of energy later in the lap.

This has barely scratched the surface of the arcane rules governing the 2026 power unit, but I hope it has shed some light on a complex subject. The changes brought in recently should help matters and improve safety in terms of reducing speed differentials, but I don’t think we have a perfect solution yet. Expect more refinement to come.

This article is one of many in the monthly Autosport magazine. For more premium content, take a look at the June 2026 issue and subscribe today. 

Drivers and engineers should appreciate the changes made for qualifying

Photo by: Andy Hone/ LAT Images via Getty Images