Why Is My EV Charging at a Lower Speed Than Usual?

If your EV is charging more slowly than expected, the most common causes are battery temperature, a high state of charge, the charger sharing power between vehicles, or a cable or setting limiting current. A charging cable not rated for your wallbox's full output is a surprisingly common bottleneck; it is worth checking the cable's rated current before assuming a fault lies elsewhere. Most slow-charging situations are explainable without a workshop visit once you work through these four areas.

Why does battery temperature reduce charging speed?

Lithium-ion cells charge most efficiently within a moderate temperature range. When the battery is cold, chemical reactions slow and the battery management system (BMS) limits charge rate to prevent damage. The same happens when the battery is too hot after a long rapid-charge stop on a warm day. Many EVs include a pre-conditioning function that warms or cools the battery before a planned fast charge; using it reduces or eliminates this speed limitation from the moment you plug in.

Is slower charging above 80% normal?

Yes, for rapid DC charging this is expected and deliberate. The BMS tapers charge rate significantly above roughly 80% state of charge, because filling the final portion too quickly stresses the cells and shortens their long-term life. This taper is less pronounced on AC home charging but is always present to some degree on DC rapid charging. If you only need 80% for your journey, unplugging at that point is often faster overall than waiting for a full charge.

Could the charger be sharing power with another vehicle?

Yes. Public rapid chargers often share their total output between two or more ports. A 150 kW dual-port unit might deliver only 75 kW to each car when both ports are occupied. If the charger screen or your car's display shows an unexpectedly low rate, try a different stall if one is free. At home, a load management device fitted to your wallbox may also reduce charge speed if other high-power appliances are running simultaneously.

Can your cable limit charging speed?

Absolutely. A cable rated for a lower current than your wallbox supports will cap your charge speed regardless of what the wallbox can deliver. Cable current ratings are usually printed on the plug or the cable body. If you are using an older cable or one bought for a lower-rated charger, it may not be rated for the full output of a modern 7 kW wallbox. Replacing it with a properly rated cable can restore full speed. Browse Type 2 cables rated for your wallbox's output if you suspect this is the cause.

Could a setting in the car be responsible?

Several in-car settings can reduce charging speed without any fault. A departure timer tells the car to time charging for a set departure, which can mean deliberately charging slowly during off-peak hours. A maximum charge level below 100% causes charging to slow or stop early. Some cars also reduce charge rate while an over-the-air software update downloads. Check your car's charging menu and any pending software notifications before assuming there is a hardware problem.

When should you contact the network or manufacturer?

If your car consistently charges significantly slower than its rated speed across multiple chargers and cables, a diagnostic check by a dealer is worth arranging. A fault with the BMS, onboard charger unit, or charging inlet can cause persistent low charge rates that the above checks will not resolve. For a consistently slow public charger, report it to the network operator via their app; most networks have an in-app fault reporting function that triggers an inspection.

Frequently asked questions

Why does my EV charge slowly on a cold morning?

Cold batteries charge more slowly because lithium-ion cells are less chemically efficient at low temperatures. The BMS restricts charge rate to prevent damage. Pre-conditioning your battery using a scheduled warm-up in the car's app, ideally while still plugged in at home, significantly reduces this effect before a rapid-charge stop.

Is charging at a lower speed harmful to the battery?

Not inherently. Slower charging at lower currents generates less heat and is gentler on the battery. The concern is only when slow charging is unexpected and points to a fault or equipment problem, rather than a deliberate BMS protection measure or a charger operating within its normal shared-power limits.

Can a granny charger charge more slowly than a wallbox?

Yes. A portable granny charger from a standard 13A socket delivers a lower charge rate than a dedicated 7 kW wallbox. This is normal; the granny charger is a backup option. Browse our portable EV charger range if you need a granny charger for travel. For regular overnight charging, a wallbox is considerably more practical.

Does rain or wet weather affect charging speed?

Not directly. Charging connectors and sockets are designed to be weatherproof to the relevant IP rating, and rain does not affect charge speed. The cold associated with wet winter weather can reduce battery efficiency and trigger BMS speed limits, but the moisture itself is not the cause. Always use a cable with no visible damage to the seals or insulation.

Can I adjust the maximum AC charge rate in my car's settings?

Some EVs allow you to set a maximum AC charge rate via the car's settings menu, sometimes to protect the battery or match a tariff window. Check your car's manual for this option. The charge rate at an AC wallbox is always limited by whichever is lowest: the wallbox output, the cable rating, or the car's onboard charger capacity.

Should I report a slow public charger to the network?

Yes, if the charger is delivering significantly less than its rated output and you have ruled out car-side causes. Most networks have an in-app fault reporting function. Note the stall number and any error codes on the charger screen. Reporting helps the network prioritise maintenance and benefits all drivers using that site.

A slow charge is usually explainable and fixable. Start with battery temperature, state of charge, and your cable rating; those three cover the majority of cases. If you need a replacement cable, browse our EV charging cable range, and find more troubleshooting advice in our charging guides.