How Long Will It Take to Charge My Electric Car?!
Let's explain a super easy way for you to calculate the charge time of your car in various locations both at home and out and about.
Charging at Home Using a 3-Pin Charge Cable
The slowest - but sometimes easiest - way to charge your car is by connecting a 3-pin charge cable to a normal socket in your home, garage, or on your driveway.
This will typically charge at around 2kW. If you have a 22kWh battery, for example, 2kW of energy will be transferred to the battery for every hour it is connected. To calculate the time to charge we divide 22 by 2. Using this method, our 22kWh battery will take around 11 hours to charge to full when completely empty.
Charging at Home Using an EV Charger
Installing a home charger can be costly but will allow for much faster charge speeds when compared to a 3-pin plug. A properly installed home charger should deliver charge speeds of around 7kW.
Using the example above - we would now divide 22 by 7 to calculate the charge time of our 2kWh battery on a 7kW charger. Our 22kWh battery would take a little over 3 hours to charge from empty to full on a 7kW charger.
Charging in Public Using a 22KW Charger
A common public charger is a Type AC charger which is capable of charge speeds of up to 22kW. This is sometimes the fastest charge speed some electric vehicles can support.
Again, using our 22kWh Renault Zoe as an example, 22 divided by 22 equals 1 hour to charge an empty battery to full.
Expanding the Maths
All of the above can of course be extrapolated for much larger batteries that exist in electric cars. Let's run through a couple of examples:
A 50kWh battery charging on a 7kW charger.
50 divided by 7 equals approximately 7 hours. 50% of the battery topped up in approximately 3.5 hours.
A 75kWh battery charging on a 100kW charger.
75 divided by 100 equals 0.75 hours which equals 45 minutes.
There is however one more thing to explain - the charge curve.
The Charge Curve
The above only works if the battery charges at a constant rate from when you first plug the car into when it reaches 100%. In reality, this does not happen.
Once the battery level gets above 80% the charge speed drops dramatically. This is to protect the battery cells and extend the overall life of the battery. Charging at top speed above 80% would drastically reduce the life of the battery. Don't worry - the car will always protect itself and reduce its charging speeds accordingly.
When using the calculations above it is always wise to add on a factor for this when you are charging right up to 80%. Many people - especially when on a long trip will only charge to 80% as it is not worth waiting the extra time to reach 100%.
When you own an EV you will become used to what it can and can't do and this will become second nature.
Always discuss with your car salesmen the charge speeds a particular car is capable of before purchasing - as not all are created equal and you need to ensure the car is suitable for your requirements both now and in the future.