One of the major concerns (if not THE major concern!) when switching over from a petrol- or diesel-powered vehicle to a battery-powered vehicle is how far you can travel between battery recharges. This distance is referred to as the vehicle’s ‘range’.
Factors that determine EV range
The driving range of an electric vehicle before it needs ‘refueliing’, just like the driving range of a petrol or diesel-powered vehicle, is determined primarily by two factors…
- Energy storage capacity
- Rate of stored energy consumption
- See also: Other EV Range Variables
Energy storage capacity
This is determined by the capacity of your battery. A small battery stores less energy than a large battery.
Battery size, or capacity, is measured in kilowatt hours (kWh). At the time of writing, a battery considered to be ‘small’ is around 45 kWh. A battery considered to be ‘large’ is over 70 kWh.
Manufacturers consider a 50 kWh battery to be ‘standard range’. Depending on the EV brand, a ‘long range’ battery could be 60 kWh or 70 kWh. Or more.
Rate of energy consumption
This is a measure of how quickly your vehicle consumes the electrical energy stored in the battery.
An EV driving around town consumes energy at the rate of around 15 kWh / 100 km (or less). The same EV driving on the highway will consume energy at the rate of around 18 kWh / 100 km (or more).
The rate of stored energy consumption, either around town or out on the highway, will increase or decrease depending on how hard you accelerate and whether the terrain is flat or hilly. EVs consume more energy pushing a vehicle up a hill but, with regenerative deceleration, can return energy to the battery when travelling down a hill, or slowing to a stop at traffic lights.
In general terms…
-
- If your battery has a capacity of 45 kWh, it can supply 15 kW per hour for 3 hours, or 18 kW for 2.5 hours.
- If your battery has a capacity of 60 kWh, it can supply 15 kW per hour for 4 hours, or 18 kW for 3.3 hours.
- If your battery has a capacity of 75 kWh, it can supply 15 kW per hour for 5 hours, or 18 kW for 4 hours.
That is very much ‘in theory’ – and if you are utilising your full battery capacity. You don’t want to run your battery completely flat so, more realistically, if you adjust those calculations based on using only 80% of your battery capacity (see next section below)…..
-
- If your battery has a capacity of 45 kWh (36 kWh @ 80%), it can supply 15 kW per hour for 2.4 hours, or 18 kW for 2 hours.
- If your battery has a capacity of 60 kWh (48 kWh @ 80%), it can supply 15 kW per hour for 3.2 hours, or 18 kW for 2.6 hours.
- If your battery has a capacity of 75 kWh (60 kWh @ 80%) it can supply 15 kW per hour for 4 hours, or 18 kW for 3.3 hours.
So, if your car has a 60 kWh battery, and you travel on the highway at 100 km/h for 2.6 hours, you should (theoretically) be able to travel 260 km before recharging.
Battery Capacity Reality
Let’s say a petrol or diesel powered vehicle has a fuel tank with a capacity of 60 litres. Which means a usable capacity of around 50 litres – you don’t want to drain it to completely empty (especially if it is a diesel vehicle).
If you are using 8 litres of fuel to travel 100 kms, a journey of 750 kms would completely empty your 60 litre tank – and leave you stranded beside the road! If you play it safe and plan on using only 50 litres of your capacity (keeping 10 litres in reserve) you have a range of around 630 kms between refills. A refill of petrol or diesel takes around 5-10 minutes at a service station.
The Lithium batteries that store the energy supply for electric vehicles are much the same. Working at the extremes, you should plan on using only 80% of their total capacity – discharging to no less 10% or 20% of total capacity – rather than using the full 100% of the battery’s stored energy capacity.
And just to make this more complicated, ‘ideal’ charging and discharging regimes vary a little depending on the chemistry of your Lithium battery – Lithium Nickel Manganese Cobalt batteries (NMC) prefer regular charging to only 80% and regular discharging to (say) 40%, while Lithium Ferrous Phosphate batteries (LFP) are happy to be regularly charged to 100% and discharged to 20% State of Charge (SoC).
The other big factor to consider when recharging your battery is that it takes a lot longer than 10 minutes – maybe 45 minutes for a full recharge of a 45 kWh battery using a 50 kWh fast charger. Less for just a ‘top-up’. Charging takes a longer time using a slower charging station, though not all EVs can take advantage of the higher charging rates available at some fast charging stations (150kWh – 350kWh).
 Where will you recharge?
If you install a 7kW wall connector at home you will rarely need to use a commercial charger – just plug in and recharge the battery overnight while you are asleep. For local commuting, battery capacity really isn’t an issue in general daily use conditions. Just plug the car in when you arrive home – home charging is much cheaper than commercial charging. And here is a ‘bonus’ of having an EV with a smaller battery – you can fully charge your battery in your 6 hour overnight EV-discounted charging period, or using electricity generated by your solar panels during the day. |
Range reality
Driving an EV at low speed consumes less stored battery energy than when driving at higher speeds – just the opposite of when comparing the fuel consumption of a petrol or diesel-powered car around town to driving on the highway. This effect is compounded in an EV by regenerative braking, where energy is returned to the battery when decelerating or braking, which you do a lot more often in city traffic than you do when traveling on the highway.
At speeds under 80 km/h an EV will be consuming around 15 kWh of battery capacity every 100 kms, increasing to maybe 18 kWh per 100 kms at freeway speeds.
Around town, at lower speeds, consuming around 15 kWh per 100 kms, and allowing for the 80% rule……
-
- An EV with a 45 kWh battery will have a range of around 220kms before needing to recharge;
- An EV with a 75 kWh battery will have a range of around around 350 kms before needing to recharge.
Out on the highway, at higher speeds, consuming around 18 kWh per 100 kms, and allowing for the 80% rule…..
-
- Expect around a 200 km range from an EV with a 45 kWh battery, before needing a recharge;
- Expect around 330 km range from an EV with a 75 kWh battery, before needing a recharge.
And all of the above is very much a theoretical average. Everything depends on how hard you push that accelerator pedal, if you are travelling up hills, or down hills, if you have regenerative braking turned on, if you are using air conditioning, or heating, if you have a large load, how much charge you have in your battery before you leave, how low you are prepared to discharge, etc, etc.
Another important factor is air temperature – the chemical reaction that occurs in your battery is less efficient in cold conditions. Your EV will have a longer range in summer than in winter!
With the above in mind, consider the figures in the table below as a rough guide only….
Battery range and charge time (EVs in Australia 2023)
- The list below is not comprehensive;
- Battery size / WLTP range is based on manufacturer website specs;
- Usable kWh is based on 90% capacity;
- WLTP – The Worldwide Harmonised Light Vehicle Test Procedure – measures the theoretical range of a car travelling at an average speed of 48 kmh in summer, with no heating or cooling systems running;
- ‘Around Town’ Real Range is calculated on 16 kWh / 100 km using 90% battery capacity;
- ‘Highway’ Real Range is calculated on 18 kWh / 100 km using 90% battery capacity;
- Charge time is based on a full charge on a 7kW home wall connector.
More reading….
|