Angel Hill, the one-way system and slow charging in Sutton
Much of Sutton's driving happens at walking pace. The A232 through the town has signal after signal and bus stops in between, and at rush hour the queues stretch back towards Cheam and Carshalton. Commuters working at the Royal Marsden and the offices near the station often do short, slow trips twice a day, and on the old Brighton road through Angel Hill and Rose Hill the traffic is similar. That's a lot of time at idle, which is when an alternator is producing its least. The battery covers the shortfall at first, so the fault stays hidden until it can't.
Around Benhilton and the streets near Manor Park, cars are tightly parked and trips are short, so batteries rarely reach full charge. On newer cars with smart charging, the engine ECU relies on stretches of steady driving or deceleration to top the battery up, and a failing alternator or decoupler pulley shows up as stop-start refusing to work, or a warning to have the battery checked. Owners heading to The London Cancer Hub site in Belmont or the stations may not notice until the car won't start in a car park.
We look at the car as a whole. The battery is tested, the alternator's output is measured across idle and higher revs with loads on, and we read battery management and charging codes from the ECU. We also check the belt tensioner, because a weak tensioner can let the belt slip and look like an alternator fault. You'll get a written quote and a realistic time before we start, and nothing is replaced without your approval.
From the town centre, take Carshalton Road (A232) east, then West Street north past Carshalton station, Wrythe Lane, and the B277 into Hackbridge, about 2.4 miles. If the car won't start, we can arrange collection. Replacement alternators are OE-specification, and our 3-month workmanship warranty covers the job.