The 12V battery runs every computer in your EV. It's small, often poor-quality from the factory, and dies after 2–4 years — locking you out of the car even when the main HV pack is full. £80–£150 to replace.
Strange but true: the most common EV breakdown is a flat 12V battery — the same kind your old petrol car had.
Can I jump-start an EV? — Yes — jump the 12V terminals only, never touch the HV system. Once running, drive it for 30 minutes to let the DC-DC converter top up the 12V.
How often should I replace it? — 3–4 years typically. If you've had two flat-battery incidents, it's done.
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email [email protected].