What spec does a long-distance family electric car really need in the UK?

I think there’s a strong case for a family pure-electric car with a modest battery, good efficiency and fast charging. As public charging points become more plentiful and powerful, the modest battery EV gets more useful. A side-effect is that the embodied energy of such a car is less than one with a larger battery (it takes less energy and resources to make) – and the car is cheaper to make and buy. In fact I’m so convinced, my family relies on two such cars. We no longer have any need to buy petrol or diesel.

We’ve got used to internal combustion engined (ICE) cars with 500 or more miles range, but how many people use this feature? Petrol and diesel are very energy-dense fuels, in other words your fuel tank doesn’t have to be very large to contain a massive amount of energy. However the ability to go long distances without a break could be promoting bad practise- and even play a part in road accidents.

Rule 91 of the Highway Code in the UK “recommends” a minimum break of 15 minutes after 2 hours of driving so that you are “Fit to drive”. Sitting for extended periods is really bad for you! At average UK speeds of 68mph on motorways and 48 on single carriageways, 2 hours driving represents 136 miles on motorways or 96 miles on A-roads. Taking these figures I calculated the required battery and rapid charge speeds.

Assuming an aerodynamic family car, what battery sizes and what charging powers would be needed to achieve this?

Battery sizes

Motorway: 136 miles, 4miles/kWh, = 34kWh battery (useable)

A-road: 96 miles, 5 miles/kWh, =19.2kWh battery (useable)

Adding, say, 33% capacity to allow for rapid charging to around 80% full, and some overhead as a “buffer” or “reserve” in case of route diversions, takes the required battery useable capacities to 45 and 26kWh.

Charging power

What charging power is required to recharge that useable capacity?

Motorway 34kWh in 15 minutes = 136kW (or in 20 minutes = 102kW)

A-road: 19.2kWh in 15 minutes = 76.8kW (or in 20 minutes = 57.6kW)

NOTE! This reasoning assumes that the car can charge at these high rates repeatedly. Not all cars can, as not all EVs have active battery cooling. In summer this can be crippling and lead to very long charging times as the charging power is reduced. Yes, I’m looking at you, Nissan!

The current Hyundai Ioniq electric meets these A-road requirements already. Even de-rating to allow for charging to only 80% full, it has 22.4kWh useable, and can charge at up to 70kW.

To meet the motorway requirements will need a 45kWh battery and 100kW charging. The charger is already in the Ioniq to meet a 20 minute charge for the motorway case – we’ll have to wait and see how large the battery in the next Ioniq will be – but I’d suggest a minimum of 40kWh is likely.

Of course the infrastructure to deliver this is also required, indeed 2018 has seen Rapid chargers popping up everywhere in the UK since this is a big business opportunity. Many networks have already announced more 50kW charging for A-roads, Alfa have installed the fastest one- a 60kW charger in Yorkshire. But it’s the 100+kW on motorways we really need to see. Charging sites in the right places, with the electricity power requirements, are already being snapped up by the likes of Tesla and others, with batteries on site being used to provide the peak power demands. Sadly the rapid chargers at motorway service areas, run by Electric Highway, are showing no signs of an upgrade- and never offered as much as 50kW in the first place. I’d argue they were never really “rapid”, just “quick” 🙂

Networks like Instavolt and Polar are cunningly siting good 50kW chargers in some great locations at hotels and leisure centres, and often at motorway junctions. In practise this is a lot more pleasant than charging at an MSA. What this doesn’t do is increase the profile of EV charging, the public don’t see much progress – other than the odd Tesla charging “farm” popping up.

Podpoint and Lidl should also be congratulated for adding Rapid charging to many stores; great for a quick picnic with their in-store bakeries.

Conclusion

Anything more than a 50kWh battery and 100kW charging is simply unnecessary in an aerodynamic car design- and even worse can encourage unhealthy, and risky driving practices. Cars like the Ioniq are showing that real world EVs are affordable and available, if not in huge numbers as yet. As far as I can make out, around 1000 Ioniq electrics had been sold in the UK as of the end of 2018, since launch in late 2016; out of 200,000 registered electric vehicles. (That said, we had no trouble finding two Ioniq electrics without waiting months!)

In practise a 28kWh battery, in an efficient car is enough for A-road driving and already very good for motorways.

If batteries are in short supply, why not make greater numbers of modest, efficient  EVs? Three Ioniqs or one Jaguar iPace?