SN from Co Dublin, asks: ‘Given the increasing incidence of winter storms, is there any issue with driving an electric car through a flood?’
Following the wet year of 2024 it’s perhaps little surprise that people are more concerned than ever about dealing with flood water on roads.
When it comes to electric cars, the truth is that EVs deal with floods far better than petrol or diesel cars – and the simple reason is air.
Consider the Rufford Ford in Nottinghamshire, England. Although now closed, this stretch of road which crossed a shallow river became an internet sensation, as hordes of cameraphone-wielding onlookers would regularly descend on the ford to watch drivers attempt to cross it.
On a normal day, the ford’s depth was such that it wouldn’t present much of an issue, but it didn’t take much in the way of rain for that depth to significantly increase, and that’s when things became entertaining for the people with cameras and expensive for the people with cars.
The advice when confronted with flood water is to get out and check the depth before trying to drive through it. Most cars will cope with around 300mm (about a foot) of standing water without too much trouble, but you still need to use the right technique, which is to enter with the engine revving high in a low gear, which keeps enough pressure in the exhaust to stop the water flowing up it. Then proceed at a steady, but not too fast, pace keeping the car’s bow wave (a wave caused by driving into the flood) where you can see it. Do that, and you ought to be okay.
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Down at Rufford Ford, too many people got rally-driver-red-mist and charged into the water at high speed, thinking that brute force would carry them through. Which, in many cases, it didn’t, and water flooded into the air intake of their cars. This is called hydro-locking, and it’s when enough liquid – water in this case – gets into the cylinders of a petrol or diesel engine, causing it to seize more or less solid. Most of the time, that means the engine is a write-off.
While you still need to be careful when dealing with flood water with an EV – the advice about checking the water’s depth and proceeding slowly still stands – the fact is that a battery and electric motor don’t need air, so there’s no concern about hydro-locking. This means that electric cars are actually much better at dealing with floods than internal combustion-engined cars.
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The batteries of an EV, along with the high-voltage wires and electric motors, are all thoroughly sealed against water, so unless there’s damage to those seals there’s simply no issue at all about driving an EV through a flood, as long as you’re being careful and adhering to the normal flood-driving advice.
It’s also true that charging points and connectors are also weatherproofed, so there’s no need to worry about charging up your car in the driving rain (although thankfully many public charging points are now gaining little canopies to shelter us from the worst of the elements), so the only concern is with home charging and the use of extension cords.
Generally the best advice is never to use an extension cord to a domestic socket to charge an EV, as the heat generation is too high for the cable and socket to cope with, but that becomes doubly dangerous in rain as most extension leads aren’t rated for outdoor use in the wet, so this is really to be avoided at all costs.
And Rufford Ford? It’s closed now – a motorcyclist who tried to charge through the water at high speed was flipped off his ‘bike and badly broke both legs, after which the access to the ford was closed off, and it doesn’t look like reopening any time soon.
