What matters more in an electric car? Charging speed or battery capacity?

Is the size of the battery really the fundamental factor when evaluating an electric car?

Audi e-Tron – (photo by Audi)

Until now, the most common approach to solving the range challenge in electric cars has been focused on increasing charging capacity, that is; the size of the battery.

In this way it is possible to obtain increasingly greater ranges thanks to batteries of greater capacity, although at the same time, this means, more recharging time and also more weight.

The size and weight of batteries cannot be drastically reduced as their chemistry does not evolve. That is, as long as a more efficient compound than the already known lithium-ion compound does not go into mass production, the density will no longer grow much.

Put simply, batteries cannot continue to grow indiscriminately, as this means increasing weight and increasing recharging times, which makes no sense.

So should battery size be the most important feature when evaluating an electric car?

Not necessarily. Some manufacturers are focusing more on reducing recharging times than on finding a way to fit larger batteries in their cars, and that is the logic. If you manage to reduce the amount of time necessary to return to an acceptable range, the size of the battery comes to the background.

Think of an older generation Mustang (the fifth). For design reasons, it had a relatively small tank (60 liters) in relation to its gasoline consumption, and with a yield of 6.38 km / liter in the city, it had just enough gasoline for 382 km, we are talking about official figures, which we already know they are always optimistic. Those who have driven one will know that gasoline had to be added too often. Because there are countless stations and the operation takes just a few minutes, this feature never posed a problem for Ford’s pony car sales, which was indeed a success.

Getting back to the point, as recharges in electric cars can be done in less time, the size of the battery will become less and less important.

But reducing recharging times is not an easy task, since there are two important questions to consider; On the one hand, the more current you put into the battery, the more heat is generated and the higher the temperature, the performance of the charge will deteriorate more and more.

On the other hand, introducing an immense amount of energy in an instant can cause long-term damage and the idea is that the batteries maintain their performance as long as possible.

Audi for example took this approach when developing the E-Tron, its 95 kWh battery is perhaps not the largest on the market (although it is large enough to tell the truth), but due to a sophisticated thermal management of the battery, based on a liquid cooling system that consists of 40 meters of ducts through which pass 22 liters of coolant, it is possible that in a 150 kW fast charger, the Audi model can receive that maximum amount of current for longer periods, which translates into shorter reload times.

We are talking that, under the aforementioned conditions, the Audi E-Tron 55 would recharge 100% of the battery in 45 minutes, while a competing vehicle will require 1 hour and 31 minutes to complete the same operation, that is, twice weather.

But just as interesting is that by recharging for 10 minutes it is possible to obtain a range of 110 km, and so on. 20 min give 220 km and 30 min, 330 km.

To put it in context, 20 minutes would be a very similar time that it would take you to refuel with a technical stop in the bathrooms, or to buy something quick like a coffee or something to eat at the convenience store.

Obviously Audi recommends recharging in a 220 volt wall box at night to maximize battery life, but even so, there is no restriction on warranty aspects for the use of a fast charger, customers can use it as much as they need it and that will not decrease the E-Tron’s battery performance.

Author: Nabeel K
Email: nabeel@wheelsjoint.com

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