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Battery Charge Rule Introduced for 2018-19

A new rule to regulate the State of Charge of the Gen 2 cars’ batteries has been confirmed…

Photo: Formula E

A new rule concerning the state of charge used with the new batteries will be introduced into the ABB FIA Formula E Championship this season.

The significant but largely overlooked regulation, which was written primarily for reliability and parity purposes, dictates that “each [car] must have a Battery State of Charge (SOC) greater or equal to 97 percent when positioned on the dummy grid.”

The rule has been set by the FIA following consultation with manufacturers and battery provider McLaren Applied Technologies in order that competitors start the race with a high SOC.

The rule is also aimed to stop a slightly lower SOC being run as it would mean that regenerative energy would be available to drivers sooner in the race.

E-racing365 understands that operating the battery at higher levels such as during the attack mode or Fanboost deployment at a low SOC can cause long-tern damage to battery cells.

It is believed that the outgoing Gen 1 cars’ Williams Advanced Engineering battery couldn’t get qualifying power below 50 percent SOC for similar reasons.

A leading technical head at one of the current manufacturers told e-racing365 that the rule will also have a fan-friendly element to it, in addition to the reliability concern for which it was formed.

“Obviously to have more regen you need somewhere to put it and if the battery is too ful’ or with a high SOC, then regen is naturally limited,” he said.

“This means that your active brake bias system has to work more accurately over a wider range.

“If you were able to start at a lower SOC then the [brake bias] operates in a more stable regenerative region making the car easier to drive and more predictable.

“This is good for engineers and drivers but less fun for the fans to watch.”

The 52 kWh allowable energy, when starting from less than 100 percent SOC, can still be achieved with the new batteries.

As some races will have 50 kWh or less usable energy, it was possible to start races with a lower SOC, but the FIA and McLaren Applied Technologies have introduced the 97 percent rule to have equality throughout the field.

Sam Smith is e-racing365's Formula E Editor. A 20-year veteran in motorsports media, including press officer roles in both the FIA Sportscar Championship and at Lola Group, Smith is a well-known face in the Formula E paddock, where he served as series editor for from 2014-17. Contact Sam

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