BatCap: EV Battery Health

Not just Tesla: 94 EVs from 17 makes in the catalog, BYD to VW — and any other EV can be added freely. No account, no car token, no cloud. Measures in airplane mode.

Buying a used EV, or selling one, comes down to a question nobody can answer from the outside: how much of the battery is still there? BatCap works it out from something you already have in front of you at every charge — the level before, the level after, and the kilowatt hours that went in.

1. LOG THE CHARGE. One big slider for the state of charge, a stepper for the kWh, a tap for AC or DC. It takes a few seconds and you can do it with cold hands at a charging column.

2. READ THE TREND, NOT THE READING. A single charge swings with temperature, with how full the pack was and with how the display rounded. So the headline is the median of your last five estimates, and the chart shows all of them against the capacity the pack had when it was new.

3. ON A FAST CHARGE, RECORD THE CURVE. Tap a button every few minutes and BatCap compares the shape against a reference curve for your model, corrected for the outside temperature. The verdict is qualitative — in the expected range, or clearly below it.

Presets cover the common models, and it works with Tesla and any EV; anything else you add by hand with its net capacity.

NO ACCOUNT, NO CAR TOKEN, NO CLOUD

The other apps in this corner want the login to your car and then hold a token that reads your location, your trips and your charges for as long as you leave it there. BatCap connects to no vehicle and to no server, because there is no server. Turn on airplane mode and every part of the app still works. There is no account, no analytics, no ads and no sync. Your charging log stays in the app on this iPhone.

THE PHOTO PATH IS OPTIONAL, THE FORM IS THE APP

If your iPhone supports Apple Intelligence, you can photograph the charging screen and the on-device model fills the figures into the form for you. Every value it fills in is labelled as an AI suggestion until you confirm or change it, because a model reading a photo of a bright screen through a windscreen gets things wrong. Nothing is saved except through the form.

On an iPhone without Apple Intelligence the camera button is simply not there and nothing else changes. Typing the numbers in is the full app, not a fallback.

ESTIMATES, NOT MANUFACTURER DATA

The new-capacity figures and the reference charging curves are estimates collected from public sources. They are not manufacturer specifications, and BatCap is not a measuring instrument. What it gives you is an indication and a direction over time, not a warranty statement and not a number to put in a contract. A brand new pack can read above 100 %, because the reference figures are conservative; the app says so rather than quietly capping it.

WHAT IT COSTS

Nothing. Logging charges, the trend, the chart and the curve comparison are all free, with no subscription, no paywall and no monthly limit. If the app helps you value a car, you can leave a tip from the settings. Tips are voluntary and unlock nothing.

REQUIREMENTS

iPhone with iOS 26. The photo shortcut additionally needs a device that supports Apple Intelligence, with Apple Intelligence switched on; everything else runs on any supported iPhone.

Questions or problems: support@freshlab.es. We answer in English, Spanish and German.