Why does my EV battery overheat when rapid charging?

Rapid charging pushes a very large current into the pack in a short time, and a proportion of that energy becomes heat rather than stored charge. The cooling system is sized for normal use, so several rapid sessions in a row on a long journey — especially in summer, or straight after fast motorway driving that has already warmed the pack — can outpace it. The car responds by slowing the charge rate and warning you. That is the system working, not failing.

Is rapid charging bad for an electric car battery?

Using rapid chargers when you need them is fine and no manufacturer suggests otherwise. Using them as your only means of charging is less good, because heat and high charging currents are two of the main things that age lithium cells. The general guidance is to do everyday charging slowly at home or at work and save rapid charging for journeys. A car that has lived exclusively on rapid chargers will typically show more capacity loss than an identical one charged slowly.

What should I do if my electric car battery overheats?

Stop rapid charging, drive gently, and park somewhere shaded to let the pack cool before charging again. Preferably use a slower AC charger for the next session, because the battery will accept a slow charge long before it will accept a rapid one. If the warning appears in mild weather during ordinary driving with no rapid charging involved, the cooling system needs investigating. If it is red, or accompanied by smoke, hissing or a chemical smell, get out, move away from the car and call 999.

Can an electric car battery catch fire?

It can, but it is rare, and the available fire statistics consistently show electric cars catching fire less often than petrol and diesel ones. What is different is the nature of the fire when it does happen: a damaged lithium pack can enter thermal runaway, which burns extremely hot, is very hard to extinguish and can reignite hours or days later. That is precisely why an overheating warning is worth respecting rather than driving through, and why any smoke, hissing or chemical smell from the car means everyone out, well clear, and 999 with the words electric vehicle used early in the call.

Dashboard warning light

EV battery temperature warning light

Last updated 27 July 2026

Quick answer

The traction battery is outside the temperature range it wants to be in, almost always too hot. The car will protect itself by cutting power and slowing or refusing rapid charging until the pack comes back into range.

What to do: Get it checked within days
Can you drive?: Briefly, gently

Why it is amber

A system has reported a malfunction, or something needs attention. The car is usually still driveable, but the fault will not clear itself and several amber lamps are an automatic MOT failure.

What turns it on

Temperature sensors distributed through the battery pack report to the battery management system, which runs the cooling circuit and, if that cannot keep up, starts limiting what the car is allowed to do. The lamp lights when the pack passes its normal operating window. A handful of cars use the same lamp at the cold extreme, when the pack is too cold to deliver or accept full current.

What to do about it

Stop rapid charging if you are plugged in. Rapid charging is the single largest heat load a battery sees, and continuing while the pack is already too hot is the one thing guaranteed to make it worse.
Ease off and drive gently. Repeated hard acceleration puts as much heat into the pack as a rapid charge does.
Park in the shade if you can, and leave the car switched on for a few minutes if the handbook says the cooling system runs while parked. On many cars the pump and fans only work with the vehicle awake.
Let it cool before charging again, and use a slower AC charger for the next session if you have time. The pack will accept a slow charge long before it will accept a rapid one.
If the lamp keeps appearing in ordinary driving, in mild weather, without rapid charging, the cooling system itself needs looking at. That is a garage job and not something to keep driving through.
If the warning is red rather than amber, or comes with a burning or chemical smell, hissing or smoke, stop, get everyone out and away from the car, and call 999.

Can you keep driving?

Briefly, gently

Yes, gently, and the gently is the whole point — the car will insist on it anyway by reducing power. Get where you are going without hard acceleration and let the pack cool before charging again. Treat it differently if the warning is red, or if it appears in mild weather during ordinary driving, because at that point the cooling system is not doing its job and continuing to load a pack that cannot shed heat is the one scenario worth being genuinely careful about.

What causes it

Repeated rapid charging, particularly several sessions back to back on a long journey
Sustained hard driving or towing in hot weather, or a track day
Low coolant in the battery thermal management circuit, which is a separate circuit from the cabin and drive unit on many cars
A failed coolant pump, chiller or cooling fan for the battery pack
A blocked radiator or condenser matrix, often full of leaves, flies and road debris at the front of the car
A faulty temperature sensor reporting a hot spot that is not there, which is the lucky outcome
Very cold weather on the cars that use this lamp at both extremes, where the pack is simply too cold to work properly

Does it fail an MOT?

No.

The MOT does not test the traction battery, its cooling system or its temperature, and there is no defect for this lamp. The one thing a tester can record is what they can see underneath: since 2018 a fluid leak that could harm the environment or another road user is a defect, and battery coolant dripping onto the road counts the same as any other. Coolant loss is also a realistic cause of this warning, so a leak found at the MOT and a temperature lamp on the dashboard may be the same problem seen from two ends.

Fault codes that turn this light on

The lamp tells you which system reported a problem. The code stored behind it names the check that failed, which is the difference between knowing something is wrong and knowing where to look. These are the ones that commonly sit behind this symbol.

P0A9CHybrid/EV Battery Temperature Sensor A Circuit Range/Performance
P0A9DHybrid/EV Battery Temperature Sensor A Circuit Low
P0A9EHybrid/EV Battery Temperature Sensor A Circuit High
P0A81Hybrid Battery Pack Cooling Fan 1 Performance
P0A82Hybrid Battery Pack Cooling Fan 1 Circuit Low

Got a different code? Look it up — the index covers every standard OBD-II code.

Common questions

Why does my EV battery overheat when rapid charging?: Rapid charging pushes a very large current into the pack in a short time, and a proportion of that energy becomes heat rather than stored charge. The cooling system is sized for normal use, so several rapid sessions in a row on a long journey — especially in summer, or straight after fast motorway driving that has already warmed the pack — can outpace it. The car responds by slowing the charge rate and warning you. That is the system working, not failing.
Is rapid charging bad for an electric car battery?: Using rapid chargers when you need them is fine and no manufacturer suggests otherwise. Using them as your only means of charging is less good, because heat and high charging currents are two of the main things that age lithium cells. The general guidance is to do everyday charging slowly at home or at work and save rapid charging for journeys. A car that has lived exclusively on rapid chargers will typically show more capacity loss than an identical one charged slowly.
What should I do if my electric car battery overheats?: Stop rapid charging, drive gently, and park somewhere shaded to let the pack cool before charging again. Preferably use a slower AC charger for the next session, because the battery will accept a slow charge long before it will accept a rapid one. If the warning appears in mild weather during ordinary driving with no rapid charging involved, the cooling system needs investigating. If it is red, or accompanied by smoke, hissing or a chemical smell, get out, move away from the car and call 999.
Can an electric car battery catch fire?: It can, but it is rare, and the available fire statistics consistently show electric cars catching fire less often than petrol and diesel ones. What is different is the nature of the fire when it does happen: a damaged lithium pack can enter thermal runaway, which burns extremely hot, is very hard to extinguish and can reignite hours or days later. That is precisely why an overheating warning is worth respecting rather than driving through, and why any smoke, hissing or chemical smell from the car means everyone out, well clear, and 999 with the words electric vehicle used early in the call.

This is general guidance, not a diagnosis. Manufacturers draw the same system differently and reuse symbols for more than one function, so check the handbook for your own car before acting on anything here.

Check what your car has actually failed on

Free MOT history for any UK registration, straight from DVSA records.