Why Your EV Range Drops at 100% Charge

100% charge and original battery capacity are different ideas

The charge percentage describes how full the currently available battery is. It does not state how much energy the battery held when new. The range display is another layer: it translates available energy into an expected distance using the vehicle’s own method. A different number at 100% can therefore reflect a changed consumption assumption, a capacity change or both. First find out how the display in your exact vehicle is calculated; do not assume every manufacturer uses the same approach.

Compare like-for-like journeys before comparing the pack

Record the date, outside temperature, recent average consumption and the kinds of trips you have driven. Motorway speeds, cabin heating, wind, tyres and road conditions can change the energy required per kilometre. A winter commute with several short trips is a poor comparison with a mild-weather journey on quieter roads. The US Department of Energy describes cold-weather effects on EV performance and heating demand. A seasonal range reduction should not automatically be entered as permanent degradation.

An illustrative calculation: same energy, different range

Suppose 54 kWh is available. At 15 kWh/100 km, the simple full-charge range is 360 km. At 18 kWh/100 km, it is 300 km. The range is 60 km lower even though the assumed usable energy is unchanged. These figures are an arithmetic example, not data from a particular model. Real trip planning also needs a reserve and conditions appropriate to the route. Do not divide a new dashboard number by an old one and call the result measured SoH.

Check what else changed

Check whether the selected charge limit, displayed unit, wheel setting or journey averaging period changed. Ask whether a software update or a battery repair preceded the difference and retain the relevant records. Do not reset data repeatedly just to recover a larger displayed number; that would make before-and-after comparisons harder. If the car shows a battery or charging warning, follow its manual and arrange an appropriate assessment instead of relying on a range calculation.

Use evidence that can separate the explanations

A recent diagnostic report with a stated method can add information about battery condition. It remains separate from a range prediction. If using the EVVerity estimator, choose full-charge range and battery-side consumption representing the same conditions and supply the correct original usable baseline. An estimate above that baseline or far from a reported SoH is a reason to review the inputs, not a reason to force the numbers to agree. Keep uncertainty visible and avoid turning a sensitivity band into a laboratory confidence interval.

Plan the trip while the cause is being checked

Use a current, relevant consumption figure and an arrival reserve in the range calculator. Try a higher-consumption scenario for adverse conditions and identify suitable charging stops. If the available evidence is weak, leave more planning margin rather than assuming the best case. The practical question is whether the trip can be planned with the evidence available today; confirming the reason for a range change is a separate diagnostic task.

What to ask the seller of a used EV

Request the complete battery report if one exists, recent consumption with its averaging period, and a range screenshot that includes charge percentage. Ask when the apparent change began, whether there were warnings and whether the pack or charging system has been repaired. Compare the information privately with the car’s identity and odometer. A seller may not know every answer; recording an unknown is more useful than filling the gap with a percentage inferred from age alone.

A before-and-after range log

Record two comparable observations rather than relying on a remembered maximum. There is no need to enter a VIN or make the log public.

Turn a discrepancy into a specific question

If consumption increased while usable-energy evidence stayed similar, explore the range effect of the new consumption before asserting degradation. If a warning appeared or a properly comparable diagnostic changed, retain the records and ask a qualified provider to interpret them. Missing evidence remains an open question; do not fill the gap by extrapolating from age.

Before you rely on the answer

• Am I comparing the same charge level, units and range-display method?
• Do the consumption figures cover similar driving conditions?
• Is there a warning or other evidence that needs professional assessment?

Worksheets and numerical scenarios are original EVVerity editorial examples. They are not observed vehicle results or market-price data.