How to charge your EV correctly to maximize its resale value

When you buy a new car with a combustion engine, its resale value is shaped mainly by regular servicing, a body free of rust and dents, and a diligently kept service book. With an electric car, however, an entirely new factor comes into play – one that can push the price up or down by thousands of euros after a few years.

That factor is the health of the traction battery (SoH – State of Health). While the mechanical parts of an electric car age only minimally, the battery's chemistry responds directly to how you treat it.

The good news is that battery degradation is largely in your own hands. If you adopt the right charging habits, you will keep the battery in top condition. When you sell the car, an independent certificate will then prove that your vehicle has a much higher capacity than the other "worn-out" electric cars on the market. So how do you do it?

1. The golden rule: Stay between 20% and 80%

Lithium-ion batteries (which power the vast majority of electric cars) work by shuttling lithium ions between the anode and the cathode. They experience the least chemical stress when they are charged to roughly half.

• Extreme discharge (below 20%): Causes high internal resistance and permanent loss of lithium.

• Extreme charging (above 80%): Creates high voltage in the battery, which accelerates its chemical ageing.

Practical tip: For everyday commuting and city driving, limit the maximum charge level to 80% in your vehicle's settings. Only charge the car to 100% when you are setting off on a long trip first thing in the morning (for example, going on holiday).

2. Beware of the "charge to 100% and go" rule

The biggest battery killer is not the 100% charge itself, but the time the car spends in that state. If you fill the car up at a fast charger and then leave it parked at the airport for two weeks in the summer heat, you deal the battery a heavy blow that immediately translates into faster degradation.

Practical tip: If you do need to charge the car to 100%, plan it so that you leave home or the charging station within a few hours of the charge finishing. While driving, the voltage quickly drops back into the safe zone.

3. Use fast chargers (DC) wisely

Ultra-fast DC chargers on motorways are a great technological achievement – they can charge a car in 20 to 30 minutes. For the battery, however, they represent an enormous strain. A massive current flows through them, generating a great deal of heat. Even with the car's advanced liquid cooling, the cells take a beating. It is better to stop more often for shorter charging sessions. This pays off twice over: during a shorter session the battery does not reach such high temperatures, and it also charges fastest in the 20%–60% range.

Practical tip: The best and also the cheapest "fuel" for an electric car is slow AC charging – ideally at home from a wallbox, from a standard 400V socket, or at city charging posts while you shop. The car charges slowly, the battery does not heat up, and its degradation is minimal. Save fast chargers primarily for long transit routes.

4. Make use of thermal management and preconditioning

Modern electric cars can work with battery temperature almost magically. If you enter a destination in the navigation and the car plans a charging stop, it automatically preheats or cools the battery on the way to the charger to an optimal 30–40 °C. As a result, charging is not only faster but also safer for the cells themselves.

How do you turn these habits into money when selling the car?

You might be thinking: "Why should I hold back when I'm going to sell the car in 4 years anyway?" The answer is simple: Financial gain.

Buyers of used EVs are no longer naive. They know a new battery costs thousands of euros. When you sell your car and provide an independent battery health certificate (SoH) showing a value of, say, 93%, you prove to the buyer in black and white that you took exemplary care of the car.

Compared with another listing where the owner "destroyed" the battery with daily DC charging to 100% and the car's health is only 82%, you can ask a 10% to 15% higher price for your vehicle. Charging correctly is not just an ecological whim – it is an investment that pays you back down to the last euro when you sell.