Why queuing at Mitcham Junction shows up a weak alternator
Anyone who drives from the Cricket Green towards Hackbridge knows the bridge over the railway and tram lines by Mitcham Junction, where traffic bunches up at peak times. Sitting in that queue with the lights, wipers and blower on is a small but telling test of an alternator, because output is at its lowest at idle. If dash lights dim, the radio resets or the battery light flickers while you're stationary and clears as you pull away, the charging system is struggling. It isn't a diagnosis on its own, but it's a useful clue.
Mitcham has plenty of older family cars and high-mileage vehicles, including taxis and private hire working the A217 and A236. On older cars the usual failures are worn brushes and a tired regulator, which make output drop in and out. On many diesels the freewheel pulley goes first, giving a rattle at idle and a belt that flaps. Around the older streets by Eagle House and The Canons, tight parking and short trips mean the battery rarely gets a full charge either. Oil leaks from a rocker cover or power steering pipe above the alternator are another common cause of early failure on older engines, so we look for those too.
Our testing separates these faults. We measure output at idle and at higher revs with loads switched on, check for ripple from failed diodes, and feel the pulley by hand with the belt off. If the pulley alone is the problem and it's available separately for your alternator, we'll tell you rather than selling a complete unit. Everything is quoted in writing first.
The drive is short: from the Cricket Green take Cranmer Road to Carshalton Road, over the bridge and past Beddington Corner into Hackbridge, about 2.5 miles. If the car won't start, collection can be arranged from Mitcham. If the fault turns out to be the battery or a corroded earth, that's what you'll pay for instead. Repairs come with our 3-month workmanship warranty.