The Difference Between a 7kW or 22kW EV Charging Point

When thinking about which type of home charging point you would like to have installed, aside from factors like price, ease of installation, etc., you also need to think about the speed of the charger.  For home charging there are essentially 2 main speeds: 7kW and 22kW (although there is a third option of an 11kW charging point that I will briefly mention). 

Aside from these home installations, you could use a 3kW charger which is a regular 3-pin plug that inserts into a normal electrical socket.  Whilst this type of charger is handy as a back-up, it is not recommended for regular use as it takes too long to and can potentially be a fire risk. 

Before we look at the difference between a 7kW and a 22kW charging point, let’s firstly look at charging times:

Range per hour

  • 3kW chargers – up to 15 miles per hour (mph) of charge (slow)
  • 7kW chargers – up to 30 mph of charge per hour (fast)
  • 11kW chargers – up to 30 mph of charge per hour (fast)
  • 22kW chargers – up to 90 mph of charge per hour (fast)

I have not included rapid chargers here as these are commercial rather than residential installations.

Effects on Battery Charge Time and Range

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Other effects to consider in relation to charge time and range are:

  • Battery Size: the larger the battery the longer the charging time
  • Battery on empty: it takes longer to charge from empty than if you have a slight charge left
  • Maximum EV charging rate: EV can only be charged at the maximum charge rate that the vehicle can accept (if your EV has a 3.6kW maximum charge rate, then it will not charge faster using a 22kW charger)
  • Maximum charge rate of charge point: If you were able to charge your EV at 11kW but only had a 7kW charger, then it would only charge at 7kW

Each EV is different, so it would be wise to check with the dealer to find out just how fast your vehicle can charge.  To have a more powerful charging unit than a 7kW installed would not necessarily mean that your EV would charge any faster.  If your onboard charger only has the capacity to pull 3.6kW then that is as fast as your EV can be charged, regardless of how powerful the charging point is.  Think of it this way… If you were heading for a country lane that was just wide enough for one car to enter, then no matter how many cars are waiting to get through, that lane can only accommodate one vehicle at a time.  It is the same with your EV battery, you may charge it on a 22kW charger point but if it only has the capacity to draw 3.6 kW, then that is as fast as it will charge. 

The Difference Between a 7kW and a 22kW Charging Point

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There are 2 main differences between a 7kW and a 22kW charging point.  Firstly, it is the speed at which they can charge an EV battery and secondly, whilst a 7kW can easily be installed on a single-phase electrical supply, a 22kW can only be installed on a 3-phase electrical supply.  A single-phase electrical supply has only one Live wire, whilst a 3-phase supply will have 3 Live wires. 

 

7kW

Most UK homes only have a single-phase electricity supply and the fastest charger you can have installed on a single-phase is 7kW.  This will charge your vehicle 3x faster than would a 3kW plug-in charger.  As far as a home installation is concerned a 7kW charger point is the best recommendation. 

 

22kW

To install a 22kW charging point requires a 3-phase supply.  It is possible to apply for an upgrade from your electricity supplier, but it will be expensive (Approximately £3,000 to £15,000). You would need to weigh up the pros and cons of this extra expense.  Even if you already had a 3-phase electrical supply, the benefits of having a 22kW charge point installed are slim because most home charging takes place at night (when electric is cheaper to use).  So, whether your EV battery took 1 hour or 5 hours to charge, you will not notice the time saved by using a faster charger.  Most EV owners merely top up the battery charge at night, so a 7kW charger is more than adequate.

 

11kW

There is a third home installation option of an 11kW charger, but similarly to 22kW, you would need a 3-phase electrical supply.  There are no real advantages at this time to installing an 11kW as there are very few EVs that can charge at 11kW (Tesler Model 3 is one that does).  As well as this, the range of an 11kW charger is no greater than a 7kW (up to 30 mph).  So, as I said earlier, a 7kW charging point is currently the best and cheapest recommendation for a home installation. 

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