Guest Blog: Mat Oxley - MotoE: is it safe? is delighted to feature the work of iconic MotoGP writer Mat Oxley. Oxley is a former racer, TT winner and highly respected author of biographies of world champions Mick Doohan and Valentino Rossi, and currently writes for Motor Sport Magazine, where he is MotoGP correspondent. We are featuring sections from Oxley's blogs, which are posted in full on the Motor Sport Magazine website.

MotoE: is it safe?

After last week’s blaze, what can MotoE learn from the hugely successful Formula E championship?

Last Thursday the entire MotoE grid was consumed by an inferno at Jerez. Riders and bikes were at the track preparing for what was supposed to be the first round of the electric-powered championship at May’s Spanish Grand Prix. Fortunately, nobody was hurt.

Electric vehicles do cause some concerns, due to the risk of electrocution and fire. Isle of Man TT marshals are equipped with special insulated rubber gloves to marshal the TT Zero race, the world’s first high-profile EV bike race. And at last year’s TT a Zero bike caught fire in the paddock and blazed for 24 hours.

The big concern is the lithium-ion batteries used in most electric race bikes and cars, including MotoE’s Energica Ego Corsa machines. Although the Jerez fire was ignited by a charging station and not by a battery, it is the lithium-ion batteries that are the usual worry.

Heat is the biggest enemy of battery performance and also the greatest danger. The problem is so-called thermal runaway, when a drastic temperature increase or damage to the battery triggers an exothermic chain reaction that leads to catastrophic combustion. This problem is magnified by the fact that these fires are very difficult to extinguish because some components of lithium-ion batteries produce oxygen as they burn.

It’s not only EV batteries that can suffer from thermal runaway – this is why some smartphones and laptops appear to spontaneously combust.

And yet lithium-ion batteries used in car racing’s Formula E series – the cutting edge of EV research and development – haven’t been a problem. Williams Advanced Engineering supplied batteries for the first four seasons of the championship, claiming just two failures and zero fires in 149,000 track miles and many hundreds of thousands of miles in planes, crisscrossing the globe to Formula E’s numerous flyaway races.

“Safety procedures were at the forefront of everything we did when we were getting ready for the first Formula E season,” says Gary Ekerold, who headed the Williams battery programme. “Safety drives costs up but you can’t take shortcuts. When you put 350kg Formula E batteries in a cargo plane those batteries need to have gone through a massively rigorous testing process.”

Read the rest of Mat Oxley's blog on the Motor Sport Magazine website.


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What is the operating voltage of these batteries? I saw the reference to insulating gloves; these are only necessary for higher voltages (say above 110v). I assume the motor is dc.

I don’t know much about electric vehicles, but the voltages can vary from around 36 to 650 at present depending on whether it’s a cycle or a car. Components may be ac or dc. Motors may be 250V. Anything over 50V is considered dangerous but it’s the current (amps) that does the damage, not the volts. Skin is a reasonable insulator but as soon as it’s scratched/broken or sweaty (saline liquids like blood or sweat are excellent conductors) your risk is exponentially higher. Because of these factors electric vehicles do not use the chassis as the return conductor for anything over 24V - you would be at too much risk. For marshals, a damaged vehicle is very risky as even normal safety devices could be breached and any part live. Carbon fibre is a good conductor , as many fishermen have discovered when casting near overhead lines..... Rubber gloves and footwear are essential and any fire must use suitable extinguishant/suppressant. Formula E have special battery casings that can be flooded with flowing water - extinguishing a battery fire can be impracticable and you just have to keep it cool whilst the energy dissipates.

Current flows could be many tens or hundreds of amps in some parts of the system under normal or fault conditions but remember that anything above 20mA could kill you, and even a few amps is usually guaranteed to stop your heart working correctly. The conflagration you can get with petrol is not likely, but there are plenty of new risks for scrutinisers, marshals , mechanics and maybe even the riders, as the battery weight will be significant too. The bikes will be cooler to ride though - heat levels for the most part are a lot lower as there is much less waste heat.

Yes I'm aware it's the current that does the damage but it the voltage that drives it of course. That's why your car battery is capable of delivering hundreds of amps to a starter motor (which is nearly a dead short) but you can put your hands across it and not feel a thing. But 30mA from a 240vac mains socket and you're flying across the room.

I'm quite excited by the technology and I hope it helps the development of what's available to the public.

I get it that if a battery is dead-shorted in a crash, there will be a lot of energy being dissipated. We shall see how this unfolds...