Mosman has one of the highest concentrations of second and third household cars in Sydney, and a second car has a battery history that almost nobody thinks about.
It sits. For days, sometimes weeks. Garaged, out of the weather, protected from the heat — which is genuinely good — and, in most households, plugged in and charged to 100% the whole time.
That last part is the problem. A lithium pack held at a high state of charge ages faster than one held at a moderate one, because a full cell sits at a higher voltage and higher voltage accelerates the chemistry that permanently removes capacity. It is not dramatic over a week. Over four years of near-permanent full charge, it is measurable.
The result is a pattern we see repeatedly on garaged, low-kilometre, well-cared-for cars: an odometer that suggests near-new condition and a pack that has aged more than the reading implies. The owner did nothing wrong. They were never told that leaving it plugged in at 100% was different from leaving it plugged in at 60%.
Almost every modern EV offers a charge limit. For a car that mostly sits, setting it to around 60% and topping up before a long trip is materially kinder to the battery than keeping it full.
Why this matters to a buyer
Mosman cars sell at a premium and the premium is largely about condition — low kilometres, full history, garaged, one owner. All of that is real and all of it is worth paying for. But the battery is the one component where the usual signals of a well-kept car do not reliably predict the outcome, and it is also the most expensive component in the vehicle.
A measurement is how you find out whether the premium is justified. Frequently it is. Occasionally it is not, and that is exactly when you want to know.
The climate advantage is real
Harbourside, temperature-moderated, heavily treed, and predominantly garaged. Heat is the primary driver of permanent capacity loss and Mosman has very little of it by Sydney standards. Cars that have genuinely lived here their whole lives usually measure well.
Where we come to
Mosman, Cremorne, Cremorne Point, Neutral Bay, Kirribilli, Kurraba Point, Cammeray, Beauty Point, Balmoral, Clifton Gardens and Spit Junction. Home garages, driveways, apartment basements, seller addresses.
Booking
Online booking is open for all Mosman and lower north shore postcodes. $249, no travel surcharge. Phone 02 7252 1390 to arrange it by voice.
EV battery testing across Sydney · North Sydney · Manly · Book a test — $249