It’s the easiest question to ask, but the hardest to answer because quite simply, it depends…
This piece appears in the Sydney Morning Herald (15-Oct) and The Age (16-Oct) as part of our documentary, Drive: Electric – airing Sunday 16-October-2022 at 3pm on Nine.
It’s the easiest question to ask, but the hardest to answer because quite simply, it depends.
It depends on how ‘fast’ your charger is, the rate of charge a vehicle can, and how much you need to charge.
It’s not as complex as it sounds though, and you can use a simple high-school mathematics formula to work everything out.
Power = Volts x Amps.
In the same way a petrol car’s fuel efficiency is measured in litres per 100km an electric car’s energy use is measured as kilowatt hours per 100km, or kWh/100km.
Right now, an average electric car uses 20kWh/100km. While some cars use less (Tesla Model 3 ~15kWh/100km) and some use more (Audi E-Tron S ~25kWh/100km), 20kWh will be our base for the recharge calculation.
A home wall plug, the slowest but most universal charging method, has 240V on a 10A circuit for a maximum of 2.4kW of power: 240V x 10A = 2400W or 2.4kW.
That means, to add 20kWh of charge to our car – enough to drive 100km – will take about 8-hours and 20-minutes. So, 20kWh required divided by 2.4kW charging = rate of charge.
While that sounds like a long time, it’s basically an overnight charge to add 100km of range. If you only drive 50km, your wall charger should be able to add that amount of range in 4hrs and 10min.
Conversely, if you need to add 400km of range (80kWh) and all you’ve got is your trusty wall socket, you better settle in as that will take at least 33 hours. Ouch.
The good news is things only get faster from here.
Adding a wallbox at home allows you to use a 30-Amp circuit for three times the power of the standard socket (240V x 30A = 7200W or 7.2kW). This gives you 100km range in under three hours.
And stepping up to public AC charging gives you the option of 11kW and the ability to shave even more time off that 100km fill.
But, things get really interesting, and convenient, with direct current (DC) fast- and ultra-rapid charging. Life here begins at 50kW and climbs.
This means you can add 100km range in under 30 minutes, or if your car and the charger can handle it, mere minutes.
Unfortunately, not all charging options are available to all vehicles. For example, some plug-in hybrid cars can’t charge any faster than a home wallbox can offer, and even popular electric cars like the MG ZS EV are capped at a maximum charge rate of 76kW DC.
The Hyundai Ioniq 5, Kia EV6 and Genesis GV60 can handle 350kW charging, where the Porsche Taycan and Audi E-Tron GT can take 270kW. Everything else is somewhere in between.
This means you need to get to know YOUR electric car, understand it’s charge rate and maximum capability in order to properly manage your charging plans.
You can learn more by watching the Drive: Electric documentary this Sunday 16 October at 3pm on Nine. The video will be available here and on 9Now after it airs.
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