The replacement itself, minute by minute
A clean battery swap on a typical saloon takes 20 to 40 minutes, and the order of operations is where workmanship shows. The technician starts by plugging a memory saver into the OBD port or the 12V socket, a small buffer battery that keeps the car's modules alive so you do not lose radio presets, seat memory, window auto-up calibration or, on some older cars, trigger a radio security code. Then, with the ignition off, the negative terminal comes off first and the positive second. That order is not fussiness: with the negative disconnected, an accidental spanner touch between the positive post and the body cannot short anything.
The job is not finished at the first start. A conscientious technician verifies charging voltage at the terminals with the engine running, confirms the stop-start system re-arms on cars that have it, performs battery registration where the car requires it, punches the warranty sticker, and takes the old battery away. If the van leaves within ten minutes of arriving, at least three of those steps did not happen.