Electric cars in floods and water: are they safe?  

Electricity and water: from a young age we’re taught not to mix the two, or suffer the consequences.  

So, are electric vehicles (EVs) safe in water? Can you drive them through floods? What about taking them through the car wash? Or charging them in the rain? 

First of all, EVs are as safe as internal combustion engine (ICE) cars in wet driving conditions, and can be charged when it is raining. And yes, you can take them through the car wash safely!

They are engineered to withstand water exposure and comply with stringent safety standards. Their electrical systems, including battery packs and high-voltage power systems, are sealed and protected against water ingress. 

However, the same caution is advised for floods as for ICE vehicles and there are certain precautions that should be taken if there is potential damage to the EV’s lithium-ion battery. 

Whether you are driving an electric vehicle (EV) or a traditional internal combustion engine (ICE) vehicle, the official advice is the same: If it’s flooded, forget it.

Always avoid driving through floodwaters; fast-moving water may be deeper and more powerful than it seems, potentially moving any car off-course.

Shallow water can be risky to drive in also, if it is flowing faster than 7km/hr. Modern cars are very airtight to ensure climate control works effectively. Water that is only 15cm is enough to stop the air intake of any vehicle, causing it to float once the water’s depth passes 30cm.

What risks are there for EVs? 

Flood waters may conceal objects that could cause damage to any vehicle, either piercing a fuel tank in an ICE car, or the battery of an EV. If there is a flood warning in your area it is important it is moved out of the alert zone. 

If damage happens to an EV in a flood, there is a risk of thermal runaway which could lead to a fire. If the damage occurs in saltwater, the risk of battery short circuits leading to fires is increased. 

Can an EV hydroplane on a wet road? 

EVs, like all vehicles, can hydroplane on wet roads. Hydroplaning, also known as aquaplaning, can lead to severe accidents. It is caused by a loss of traction between the tyre and the road surface. 

Around 20 per cent of wet weather accidents are due to hydroplaning according to research published by the IEEE (Institute of Electrical and Electronics Engineers). It found that EVs are less likely to hydroplane compared to ICE cars of similar size because of the added weight of EV batteries.  

The study also found a 54.4 per cent decrease in hydroplaning with increased weight and surmised that if all vehicles were electric, wet weather accidents due to hydroplaning could be reduced from 20-10 per cent. 

What about regenerative braking in the rain? 

There have been some reports of electric vehicles hydroplaning because of “one pedal” driving possible due to regenerative braking.  

One pedal driving allows the driver to slow the car down without putting a foot on the brakes. Some EVs allow the driver to adjust the level of regenerative braking but some do not. 

When the accelerator is released, the EV’s motor resistance increases, recovering energy to the battery and slowing the car down. If this is done suddenly, there is a minor chance the effect of braking could lead to a loss of traction in very wet conditions. 

While there are no published studies linking a higher incident of hydroplaning with one pedal driving, care should always be taken to avoid sudden braking of any kind on a wet road as it can result in a loss of control.  

While the risk of electrocution in submerged EVs is low, caution is advised. But bubbles around a submerged EV may indicate a damaged battery and the presence of toxic gases.  

If a submerged EV appears to be damaged, smoking, or there are gas bubbles visible, NSW Fire and Rescue recommends a call to Triple Zero (000), informing the operator that the car is an electric vehicle.  

Do not try to charge the vehicle after it has been retrieved. Although EV battery fires are uncommon, there is a risk a damaged lithium-ion battery may catch fire days or even weeks after the incident, and it must be inspected by a qualified technician. 

Call the vehicle sales point or manufacturer for advice and keep the vehicle 15 metres away from any buildings or other vehicles.  

Charging an EV in the rain or after driving in wet conditions is safe, particularly when using EV fast chargers or destination chargers.  

Like EVs themselves, EV public chargers are made to strict safety regulations. However, it may be possible to purchase EV home chargers from overseas that do not comply with Australia’s safety standards.  

Always use chargers supplied with the device or certified third-party chargers compatible with the battery specifications. Ensure these chargers bear the Regulatory Compliance Mark. 

Also, avoid using multi-socket extension cords or domestic plugs in wet conditions where there is risk of water contacting electrical points. 

It is perfectly safe to drive an electric car through an automated car wash. It’s a good idea to make sure there is enough driving range to drive it out again, though! 

Whether using a manual or automated car wash, scrubbing electrical contacts should be avoided (this is true in the case of an IE vehicle also!) 

The high-voltage components, however, are hidden and sealed to prevent damage. And, all cars, including electric vehicles, are tested for leaks before being sold. 

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