EV Charging Slowly at a 250 or 350 kW Station: 9 Reasons You May See Only 50–100 kW

You pull into a high-power EV charging station. Large lettering on the charger says 350 kW. The navigation system shows that only a short charging stop should be needed before the next destination. You connect the cable, authorise the payment and the charging session begins.

35 kW.

A moment later, 58 kW.

Then 76 kW.

At a similar charger beside you, another electric car is showing more than 200 kW.

The first reaction is understandable: something must be wrong.

If the charger says 350 kW, why is my car receiving only 76?

Is the charging operator being misleading?

Is the battery already worn out?

Perhaps the manufacturer's claim of “up to 200 kW” was never realistic?

In reality, DC fast charging is much more interesting than a single number printed on the side of a charger.

EV charging power does not work like a fuel nozzle that can simply be opened fully. During a DC charging session, the car and charger communicate continuously. The battery-management system evaluates cell temperature, state of charge, voltage, current, battery condition and other parameters, then tells the charger how much power the battery is prepared to accept at that particular moment.

That is why the same car at the same 350 kW station may exceed 200 kW on one day but accept only 70 kW on another.

And on both occasions the vehicle may be functioning perfectly normally.

A 350 kW charger does not mean “the car will receive 350 kW”. A better way to think about it is this: the charger is capable of offering up to 350 kW, while the vehicle continuously decides how much of that power it is prepared to accept.

First, understand the difference between kW and kWh

These two abbreviations are frequently confused in the EV world, but they describe two very different things.

kWh, or kilowatt-hours, describes an amount of energy. For example, a battery may have a usable capacity of 60, 77 or 100 kWh.

kW, or kilowatts, describes power — how quickly that energy is being transferred at a particular moment.

If 60 kWh of energy could theoretically be delivered continuously at exactly 60 kW, it would take roughly one hour. At 120 kW, it would theoretically take half an hour.

But an EV battery does not charge at one constant power level.

That is where the charging curve begins to matter.

Peak charging power and average charging power are not the same thing

Vehicle specifications often contain phrases such as “DC charging up to 200 kW”, “up to 250 kW” or “up to 320 kW”.

The most important words are “up to”.

Peak charging power may be available only within a particular battery SOC and temperature range, and sometimes for only a few minutes.

After that, power decreases.

That means two EVs with the same 250 kW peak rating can have completely different real charging times. One may briefly hit 250 kW and then quickly fall to 120 kW. Another may peak at only 220 kW but remain above 180–200 kW for a much larger part of the session.

The second car could therefore complete a 10–80% charge faster even though its headline maximum is lower.

A simple example

Suppose approximately 60 kWh of energy enters the battery during a 20-minute charging session.

Twenty minutes is one third of an hour.

The average power over that period would therefore be approximately:

60 kWh ÷ 0.333 h ≈ 180 kW.

The car may have briefly shown 250 kW at the beginning of the session, while averaging roughly 180 kW across the full 20 minutes.

That is completely normal.

Why does charging power fall as the battery fills?

Most electric cars can accept their highest DC charging power at a relatively low state of charge.

As the battery fills, cell voltage approaches its upper operating limit and the battery-management system must become more conservative.

The BMS therefore gradually reduces the permitted charging current.

Porsche, Tesla, IONITY and other vehicle manufacturers and charging operators all point out that a higher SOC generally means lower available DC charging power.

In many vehicles, the reduction becomes particularly noticeable at around 80%.

So when someone asks, “Why does my car charge at only 45 kW on a 350 kW charger when the battery is already at 87%?”, the answer is often very simple:

because that is how the system is designed to operate.

1. The car physically cannot accept the charger's full 250 or 350 kW

This is the first thing to check.

You can connect a vehicle with a maximum DC charging capability of only 75, 100 or 150 kW to a 350 kW charger.

The charger will not force more power into the battery than the vehicle requests.

IONITY gives a very straightforward example in its technical support information: if a vehicle can accept a maximum of 100 kW, connecting it to a 350 kW charger cannot make it exceed the vehicle's own limit.

It is especially important to check different versions of the same model.

A smaller battery may have a different DC maximum from a larger one. An older model year may differ from an updated version. Charging hardware or software may also vary between markets or production versions.

So it is not enough to know, “I own this particular EV model.”

You need to know the exact battery version and model year.

2. Battery SOC is already too high

If you arrive at a 350 kW charger with the battery already at 72% and expect the vehicle's absolute maximum charging power, you may simply have missed the fastest part of the charging curve.

Many EVs achieve their highest charging power at a low or moderate SOC.

After that, power is gradually reduced.

Above 80%, the reduction often becomes particularly noticeable.

This is one reason why, on a long journey, it can sometimes be faster to charge from roughly 10% to 70 or 80%, continue driving and make another short charging stop later rather than waiting for 100% at every station.

Of course, if you genuinely need 95% to reach the next charger, charge to 95%.

But purely from a charging-speed perspective, the final percentage points are often the most expensive in terms of time.

3. The battery is too cold

In Latvia and other cold climates, this is one of the most important causes of slow DC charging.

It is −12 °C outside in the morning. The car has been parked outdoors all night. You drive seven kilometres to the nearest fast charger and connect at 15% SOC.

The state of charge looks ideal.

But the battery may still be far too cold.

Lithium-ion cells at low temperature cannot safely accept extremely high charging currents in the same way they can within their optimum temperature range. To protect the battery, the BMS limits charging power.

IONITY specifically identifies a battery that is too cold as one of the common reasons for slower fast charging.

A simple ten-minute winter drive therefore does not necessarily mean that a traction battery weighing several hundred kilograms has already reached its ideal charging temperature.

This is exactly why newer EVs use active battery thermal management and battery preconditioning.

For more on winter energy consumption and where some of an EV's energy goes in cold weather, see our guide to winter electrical loads, cabin heating and energy consumption.

4. The battery is too hot

Cold weather is not the only temperature-related limitation.

A battery that is too hot can also cause the BMS to reduce charging power.

This can become relevant on a very hot summer day, after sustained high-speed driving, after heavy vehicle loads or after several high-power DC charging sessions within a short period.

Modern electric vehicles with well-designed liquid thermal-management systems actively try to keep the battery within an appropriate temperature window.

But physics cannot be completely eliminated.

If the system first needs to cool the battery, the vehicle may temporarily refuse to accept maximum charging power.

That is why IONITY lists both batteries that are too cold and those that are too hot among the possible causes of slow charging.

5. Battery preconditioning was not activated

This is one of the most interesting hidden conditions of modern EV fast charging.

In some vehicles, all you need to do is select a compatible DC fast-charging station as the destination in the car's built-in navigation system.

The car recognises that a high-power charging stop is approaching and begins heating or cooling the battery while still on the road so that it reaches a more favourable temperature before the cable is connected.

Porsche Charging Planner, Tesla navigation and systems from various other manufacturers use this general principle.

But there is a catch.

If you drive to the charger using only Google Maps or Waze on your phone, the car itself may not know that your destination is a DC fast charger.

Preconditioning may therefore not start.

The result can be particularly obvious in winter: you arrive at a 350 kW charger with 10–15% SOC but see only 40–70 kW during the first few minutes.

As the battery warms, charging power may begin to rise.

Before a long journey, it is therefore worth reading the owner's manual and finding out exactly how battery preconditioning is activated on your particular vehicle.

For some cars it is automatic. Others require the charging station to be selected in the built-in navigation system. Some provide a manual function or require certain conditions to be met.

6. The charger is sharing power with another vehicle or the site has a local power limit

Now the limiting factor really may be outside the vehicle.

Not every charging-station architecture can provide the full advertised power independently to every connector regardless of what is happening at the neighbouring stall.

Some high-power charging systems use shared power modules and dynamic power distribution.

For example, one ABB Terra HP configuration can provide up to 350 kW to one vehicle, while simultaneous use of two outlets can allow the system to divide power at up to 175 kW per vehicle.

Other modern configurations use dynamic power allocation — a vehicle capable of accepting more power at that moment may receive a larger share, while power can be redirected to another vehicle as the first battery fills and begins requesting less.

The electrical connection for the entire charging site can also become a limiting factor.

If several high-power chargers are operating simultaneously, the operator may use load management, battery energy storage or other systems to remain within the site's electrical capacity.

A full charging hub can therefore behave differently from the same location at three o'clock in the morning when yours is the only connected vehicle.

This is not a universal rule, however. Many high-power charging networks can provide very high independent output to each stall. The exact charger configuration must be checked.

7. A 400 V or 800 V architecture affects how easily very high charging power can be reached

This initially sounds very technical, but the basic principle is easy to understand.

Electrical power is approximately the product of voltage and current:

power = voltage × current.

In a simplified example, if a charger can supply 500 A and the vehicle's battery voltage at that moment is around 400 V:

400 V × 500 A = 200,000 W, or 200 kW.

At approximately 800 V and the same 500 A current, the theoretical result would be:

800 V × 500 A = 400 kW.

In a real vehicle, battery voltage is not a constant “exactly 400 V” or “exactly 800 V”. The charger has its own voltage and current limits, and everything is ultimately restricted by the battery and charging-system design.

But the example demonstrates why a higher-voltage system can achieve very high power using less current.

That reduces electrical losses and makes extremely high charging power easier to deliver.

However, an 800 V vehicle does not automatically mean 300 kW at every charging station.

The charger's voltage range must be compatible, sufficient current must be available and the vehicle itself must be capable of accepting the power.

A useful real-world example is the Porsche Taycan: current Porsche information lists up to 320 kW of DC charging power for certain Taycan versions on suitable 800 V infrastructure, while maximum power on 400 V infrastructure can be significantly lower for the relevant charging system.

The Hyundai IONIQ 5, meanwhile, uses an 800 V architecture while also supporting 400 V charging infrastructure through the vehicle's multi-voltage charging technology.

So the “350 kW” label alone is not enough.

What matters is electrical compatibility between the charger and the vehicle.

8. The charging station, cable or connection can limit power

High-power DC charging involves enormous electrical power, and the charger itself has thermal-management and protection systems.

Very high currents often require liquid-cooled cables and connectors.

If the cable, connector or cooling system becomes too hot or a technical problem is detected, the charger may reduce available current or stop the session for safety.

Extremely high ambient temperatures can also cause some charging systems to reduce output, a process often called derating.

This gives us a useful diagnostic principle.

If the vehicle consistently charges suspiciously slowly at one particular charger but immediately reaches much higher power after moving to another charger at a similar SOC, the first station is a much stronger suspect than the vehicle's battery.

Tesla also advises trying another Supercharger stall at the same site when charging problems occur, because an individual charger or cable can develop a fault.

9. The car itself is protecting the battery — or there really is a technical problem

Only after the previous eight explanations have been ruled out does it become reasonable to suspect a genuine vehicle fault.

The battery-management system continuously monitors battery temperature, voltage, current and individual cell behaviour.

If a parameter falls outside the desired operating range, the BMS can limit charging power.

Sometimes this is completely normal protection.

But if the vehicle previously reached 170–200 kW regularly at similar SOC and temperature conditions, yet suddenly cannot exceed 60 kW at several different known-good charging stations, diagnosis becomes worthwhile.

Possible causes can include a software problem, an issue with the battery thermal-management system, incorrect sensor data, a charging-system fault or another protection condition.

Battery ageing can theoretically affect the ability to accept very high charging power as well, but it would be wrong to see one 70 kW charging session and immediately conclude that “the battery is finished”.

The condition of a used EV battery needs to be assessed much more broadly — using SOH, actual usable capacity, cell behaviour, fault history and other data.

For more on how some of these data will become more standardised in the future, see our guide to the EV battery passport, SOH and battery data from 2027.

What does a good fast-charging session look like?

If you want to determine whether your EV is charging as intended, do not make a judgement from a single minute.

At the beginning of a charging session, communication takes place between the vehicle and charger. Some systems gradually ramp up towards the requested power.

Then the vehicle follows its own charging curve.

Imagine a hypothetical electric car with a maximum DC charging capability of 220 kW.

These figures are only an illustrative example, not the charging curve of a particular model.

But the shape demonstrates the central principle: DC charging power is a curve, not a horizontal 220 kW line from 0 to 100%.

Why is 10–80% charging time often more useful than the peak kW figure?

This is why manufacturers increasingly publish a 10–80% charging time alongside maximum charging power.

For example, Hyundai currently states that the IONIQ 5's 800 V system can charge from approximately 10 to 80% in around 18 minutes under suitable conditions when connected to compatible high-power infrastructure.

Porsche also states roughly 18 minutes from 10 to 80% for current Taycan versions under suitable conditions with compatible 800 V high-power charging infrastructure, together with maximum DC charging power of up to 320 kW for certain versions.

That can be much more informative than a single maximum number.

If an EV advertises 250 kW but holds that level for only 30 seconds, it may matter less on a road trip than a lower peak that maintains 180–200 kW through a large part of the charging curve.

Do you always need to find the most powerful 350 kW charger?

No.

If your vehicle can accept no more than 100 kW, a 350 kW charger offers no charging-speed advantage over a good 150 kW station that can continuously supply the vehicle's maximum request.

Even if the car is capable of 230 kW, at 85% SOC it may request only 60 kW.

At that point, there may be practically no difference between a 150 and 350 kW charger.

When planning a journey, knowing your vehicle's charging curve is therefore more useful than always chasing the biggest number shown on the map.

Practical test: how can you check whether the car really is charging too slowly?

If you repeatedly suspect that your vehicle never reaches its expected charging performance, you can carry out a useful comparison test without workshop equipment.

Repeatability is the key.

One slow charging session proves very little.

Five slow sessions at different reliable chargers, all beginning at low SOC with the battery properly prepared, provide far more useful diagnostic information.

What can charging behaviour tell you?

Does a larger battery automatically mean higher charging power?

No.

A larger battery capacity in kWh does not automatically mean a larger maximum charging power in kW.

Charging performance is determined by cell design, electrical architecture, cooling, BMS strategy, voltage and many other factors.

Within one model family, however, a larger battery can sometimes accept a higher absolute charging power because more cell groups are operating in parallel.

Once again, this is model-specific.

If you are still choosing an electric vehicle and trying to decide how much battery capacity you genuinely need for everyday use, see our guide to choosing a 40–60 kWh EV battery for everyday driving.

Is charging to 100% always bad?

Two separate questions need to be distinguished here.

The first is whether you need 100% for the particular journey.

If you do, charge as much as necessary.

The second question is whether charging from 80 to 100% is the fastest way to add driving range during a road trip.

Usually, it is not.

This is exactly the range where DC charging power falls significantly in many electric vehicles.

On a long journey, several shorter charging sessions in the lower SOC range can therefore be quicker overall.

However, everyday charging limits should be set according to the recommendations for your specific vehicle because battery chemistries and BMS strategies differ.

Mini test: is 70 kW normal or is there a problem?

Myths and facts

Frequently asked questions

Conclusion

At an EV fast-charging station, the easiest thing to focus on is one large number.

350 kW.

It looks like a promise.

In reality, it is only one of the system's limits.

The charger is effectively saying: “Under the right conditions, I am capable of delivering up to this much power.”

The vehicle answers: “At this particular moment, I am prepared to accept this much.”

The actual charging power is determined somewhere between those two figures.

If the vehicle can accept a maximum of 100 kW, a 350 kW charger will not turn it into a 350 kW car.

If the battery is already 90% full, even a very fast-charging EV may accept only a few dozen kilowatts.

If the battery is extremely cold on a winter morning and preconditioning was not activated, the BMS will deliberately reduce charging current.

If the battery is too hot, the same thing can happen for the opposite thermal reason.

If the charging station is sharing power modules with another vehicle or operating in a restricted mode, even a perfectly prepared EV may not receive the power you expected.

Only after these factors have been ruled out does it become reasonable to suspect a technical problem with the vehicle itself.

That is why the smartest way to judge EV fast-charging performance is not to ask:

“How many kW did I see at one particular second?”

There are much better questions.

What SOC did I arrive with?

Was the battery at the right temperature?

Was preconditioning activated?

What is the maximum DC limit for my exact vehicle?

What does its normal charging curve look like?

And how many minutes did it actually take to charge from 10 to 80%?

That final question often tells you the most.

An EV advertised with a 300 kW charging peak but able to maintain that maximum only briefly may not be faster on a road trip than a vehicle with a lower peak but a much stronger average charging rate.

The charging curve matters more than one impressive peak number.

And that is something worth checking increasingly carefully before buying an electric vehicle.

Not only:

“How far can it drive?”

But also:

“How quickly can I put those kilometres back into the battery?”

Driver's short takeaway: 250 or 350 kW printed on a charging station is not guaranteed charging power for your vehicle. First find out your EV's own maximum DC charging power and normal charging curve. Peak power is usually easiest to achieve at a low SOC with the battery at an appropriate temperature. A cold or excessively hot battery, missing preconditioning, high SOC, 400/800 V and current limitations, shared charger power and problems with the charging station itself can all reduce the kW figure without indicating battery damage. If you want to test the car objectively, arrive at a known reliable high-power charger with roughly 10–20% SOC, precondition the battery correctly and observe the complete charging curve up to around 80%. One slow session does not mean the battery is faulty; repeatedly low power at several chargers under the same favourable conditions is a much stronger reason to investigate.