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EV Charger Slow Or Not Charging Fully
Your EV charger is charging much slower than expected or the car is not reaching a full charge.
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What's happening?
A home EV charger that charges slower than expected may be operating at reduced power, being limited by the vehicle, or experiencing a supply issue. Most UK home chargers supply 7.2kW (32A single phase), which should add about 25-30 miles of range per hour. If charging is significantly slower, something is wrong.
What usually causes it?
- Charger has reduced power due to load management or supply limitations
- Vehicle's onboard charger limiting the charge rate
- Low supply voltage to the charger
- Charger operating in a reduced-power fault mode
- Smart charging schedule limiting charge speed during peak hours
- Charging cable rated lower than the charger output
Is it dangerous?
Slow charging is not a safety issue. However, if the slow charging is caused by low supply voltage, this could affect other appliances in your home. If other appliances are also performing poorly (dim lights, slow appliances), the supply voltage should be checked.
Can I fix it myself?
Check the charger app for any power reduction settings, smart charging schedules, or load management features. Some chargers reduce power during peak hours or when other household loads are high. Check that you are using the correct charging cable — a 16A cable on a 32A charger will limit the charge rate. Check the vehicle settings for any charge rate limits set in the car's software.
When should you call an electrician?
Call an electrician if the charger is supposed to deliver 7.2kW but consistently charges much slower, if you suspect a supply voltage issue, if the charger was always slow since installation, or if the charge rate dropped suddenly compared to previous performance.
What will the electrician actually do?
- Measure the supply voltage and current at the charger during a charge session
- Check the charger settings and power output configuration
- Verify the cable sizing from the consumer unit to the charger is adequate
- Test for voltage drop across the circuit under load
- Adjust charger power settings if configured incorrectly
- Liaise with the DNO if the incoming supply voltage is consistently low
What will it cost to fix?
£80–£250
Configuration and supply checks are at the lower end. If cable upgrades are needed because the original installation used undersized cable, costs will be higher.
Find an electricianFrequently asked questions
We’re happy to answer all your questions.
How fast should my home EV charger be?
A standard UK home charger on a single-phase supply delivers 7.2kW (32A). This adds approximately 25-30 miles of range per hour for most EVs. Some older homes may be limited to a 3.6kW (16A) charger if the supply is restricted.
Why is my charger showing a lower kW than expected?
The charger may have been configured for a lower output during installation, or smart features like load management may be reducing the power. Check the app settings first.
Could my electricity supply be the limiting factor?
Yes. Some UK homes have a 60A or even 40A main fuse. A 32A EV charger uses a significant portion of this. If your overall demand exceeds the supply capacity, the charger's load management will reduce its output.
Will upgrading my main fuse help?
Your DNO can upgrade your main fuse to 80A or 100A, usually for free. This gives more headroom for EV charging. Contact your DNO to request a supply upgrade.
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