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.
Charging Reality
Commercial charging stations – in shopping centres, highway service centres, etc – are handy if you are travelling away from our local area for an extended trip, but otherwise each time you return home (and the remaining range bas dropped below, say, 100km) plug the car in. Just like your mobile phone or other mobile devices. Much cheaper charging at home too! |
Forget the old ‘petrol mindset’ of regularly stopping off at service stations to top up your energy supply – we do most of our car battery charging at home.Energy consumption
We are all familiar with our current vehicle’s fuel tank capacity (litres), and rate of fuel consumption (litres per 100 km) – a combination of which determines how far we can drive a petrol or diesel powered vehicle before we need to refill the fuel tank.
Electric cars are much the same – except instead of consuming energy from a liquid in a fuel tank, EVs consume energy from a battery. The energy capacity of a battery is measured in kilowatt hours (kWh). The vehicle’s rate of energy consumption is measured in kWh per 100 kms.
Most EV’s energy consumption is around 15 kWh/100 km in stop / start driving around town, or 18 kWh/100 km (or more) on the highway at 100 km/h…..
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- 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 had a capacity of 75 kWh, it can supply 15 kW per hour for 5 hours, or 18 kW for 4 hours.
In theory – if you are utilising your full battery capacity. More realistically, if you adjust those calculations based on using 80% capacity…..
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- 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 had 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 your 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 only takes around 5 minutes at a service station.
The Lithium batteries that provide the energy supply for electric vehicles are much the same. You should work on using only 80% of their total capacity – charging to 90%, discharging to 10% – rather than using the full 100% of capacity. This will result in a longer battery life-span. (More recent Lithium Iron Phosphate batteries are happy to be charged to 100%)
And of course, the other big factor to consider when ‘refilling’ your battery is that it takes a lot longer than 5 minutes – maybe 45 minutes for a full recharge of a 45 kWh battery using a 50 kWh charger. Less for just a ‘top-up’. Charging takes a longer time using a slower charging station.
Reality check? We have installed a 7kW wall charger at home. We rarely need to use a commercial charger – just plug in and recharge the battery overnight while we are asleep. For us, battery capacity really isn’t an issue in general daily use conditions. Just plug the car in when we arrive home. (Here is a ‘bonus’ of having an EV with a smaller battery – we can fully charge our battery in our 6 hour overnight EV-discounted charging period.)
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. Thus effect is compounded 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……
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- 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…..
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- 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.
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….
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