On EVs in water

One of the most frequent questions I encounter, whether serious or not, is about driving an EV in the rain, or through a carwash. Of course, EVs are well built, and the normal expectation of driving is that they encounter wet weather all the time. Of what use would windscreen wipers be otherwise?

But, I suspect that these questions are fuelled by misinformation from parties who are against the decarbonising of our transport, such as the fossil fuel industry. The misinformation campaign against EVs is quite insidious.

But how do cars cope with floodwaters? And how do EVs cope?

How well cars cope with floodwaters depends on a couple of factors - the weight of the car, and the speed of the water flow. For a small car, with slowly moving water, it's possible that it can float in as little as 150 mm of water. Larger cars and 4 wheel drive vehicles can cope with deeper water, but there's the psychological effect of being in a 4WD vehicle and expecting to be immune to any issues! Of course, once you're floating you lose any ability to control the vehicle.

Driving an internal combustion engine (ICE) powered vehicle through water is also at the risk of water entering the air intake, causing the engine to stop, and potentially causing a lot of damage. During my drive home from the Elton John cancellation, I saw a few cars on the side of the motorway, no doubt suffering ill effects of the wet weather.

EVs are generally heavier than the equivalent size car because of the weight of the battery. So, EVs will cope better with water and with a lot of the weight being at the bottom of the car, probably better than an equivalently heavy ICE vehicle.

But, I suspect that people have the perception that water and electricity don't mix, which is probably a healthy attitude to have. (Still, the pedant in me needs to point out that pure water actually doesn't conduct electricity - it's the impurities in it that allows conduction!)

Still, the systems in an EV are well protected against ingress of moisture, even in extreme conditions - up to a point. I'd not want to drive through deep water in one though. Even if you can retain traction, at least in my EV, there would come a point where the water would be high enough to encroach into compartments where there shouldn't be any water.

The main danger with EV batteries is puncturing. Then water would be a definite problem.

But it all comes back to the evidence. The incidence of vehicle fires is much higher in ICE vehicles than in EVs, though I'll admit that there have been a few spectacular incidents involving EV fires.

Ultimately, flood situations are dangerous for driving and one should be careful. Slow down, and approach surface water and flooded streets with extreme caution. Stay safe out there!