Start with the car’s own recommendation

There is no single percentage that is correct for every electric car. Battery chemistry, usable buffers and battery-management software differ. Some models tell the driver to use an 80% daily limit, Volvo generally recommends 90% for everyday driving, and some cars ask for a regular 100% charge so that the battery-management system can calibrate accurately. The limit shown in the car or its current manual should therefore outrank a generic internet rule.

For a typical nickel-rich lithium-ion battery, a calm default is to set the car’s recommended daily limit, plug in when convenient and raise the limit shortly before a journey that needs the extra range. Renault, for example, advises 80% for daily use and 100% before a long trip; Volvo advises 90% for daily driving and notes that some cars should reach 100% weekly. Those are manufacturer instructions, not proof that 80% or 90% is universally optimal.

  • Open the charging screen or manual and identify the recommended daily limit for the exact model and battery.
  • Schedule a higher limit to finish close to departure rather than leaving the car full for days.
  • Use 100% when the journey needs it; the aim is to reduce unnecessary time at an extreme state of charge, not to surrender useful range.
  • If the displayed recommendation changes after a software update, follow the updated manufacturer guidance.

What measured evidence says—and what it cannot prove

Geotab’s 2026 analysis used telematics from more than 22,700 EVs across 21 models. It reported average degradation of 2.3% a year. Vehicles with DC fast charging in less than 12% of sessions averaged 1.5% a year, while the group that used DC frequently and exceeded 100 kW often averaged 3.0%. Hot-climate operation was associated with about 0.4 percentage points more annual degradation than mild-climate operation.

That is valuable real-world evidence, but it is observational fleet data, not a controlled trial of two otherwise identical cars. Models were anonymised, chemistry and thermal management differed, and charging behaviour can be connected with mileage and working conditions. The results support using slower AC charging when it is convenient; they do not show that an occasional motorway rapid charge damages a battery or should be avoided on a trip.

A single-car test points in the same reassuring direction from another angle. ADAC measured 89% state of health, with a stated test tolerance of plus or minus three percentage points, in its Volkswagen ID.3 after more than 220,000 km. The car was frequently charged to 100% for the endurance programme and sometimes left standing full. This is an instrumented long-term result, but it remains one vehicle. It shows that full charging is not automatically catastrophic; it does not predict every battery’s future capacity.

Build a routine around time, temperature and need

For everyday driving, use the lowest charging power that comfortably replenishes the car before it is needed. A proper AC wallbox is usually enough overnight and gives the car time to manage battery temperature. Reserve high-power DC charging for journeys and days when its speed has real value. Repeatedly choosing a slower charger during a long trip only to protect the battery can waste hours for a benefit that may be small and model-dependent.

Heat deserves more attention in Portugal and southern Europe. ADAC advises avoiding long periods near empty or full, especially in high temperatures, and Volkswagen recommends stopping around 80% in hot weather where practical. Shade or covered parking can help when available. The battery-management system still provides the primary protection, so owners should not improvise cooling or interrupt charging because a fan, pump or compressor starts running.

At a rapid charger, stopping around 80% is often a time decision as well as a battery decision: charging power normally tapers as the pack fills. Continue beyond 80% when the next reliable charger is distant, the weather is poor, towing increases consumption or an accessible charging stop is uncertain. A safe arrival reserve matters more than rigidly obeying a percentage slogan.

Long parking needs a different setting

A car that will sit unused for weeks should not normally be left at either 0% or 100%. Check the model manual for a storage target and whether the car should remain plugged in. Volvo’s current guidance for the EX90, as one model-specific example, recommends 40–60% for parking longer than a month and a 50% limit while plugged in for more than three months. Another model may specify a different level or procedure.

Remember that the high-voltage battery may support the low-voltage system differently depending on the vehicle and software. Before a long absence, disable avoidable energy users, confirm that scheduled climate control is off, check connectivity and arrange for someone to inspect the car if the manual recommends it. Do not assume that a healthy traction battery guarantees the 12-volt battery cannot discharge.

Ignore battery theatre; watch the useful signals

Dashboard range is not a battery-health test. It changes with recent speed, weather, heating, route and driving style. A lower estimate after a fast motorway journey does not prove capacity loss. Look instead for a persistent fall in usable energy under comparable conditions, repeated charging faults, warnings or a material change confirmed by service diagnostics.

Owner groups are good at revealing practical quirks: a model that resets its charge limit after an update, a public charger that repeatedly ends sessions early or an app schedule that conflicts with the wallbox. Reports such as ‘I always charge to 100% and lost no range’ remain anecdotes because the displayed range, climate, mileage and test method are uncontrolled. Treat them as questions to investigate, not measurements to apply to every car.

A workable routine is simple: follow the model-specific daily limit, time a full charge for departure when extra range is useful, favour AC charging in normal life, rapid-charge without guilt when travelling, and avoid storing the car very full or very empty. Sources and manufacturer guidance were checked on 9 September 2026; revisit the current manual after software updates or before long-term storage.