Yesterday I proved once again that an alternator will support a battery until the battery is utterly dead. I found that with a dynamo (and to an extent engines that took a few turns to wake up) there was plenty of warning that a battery was on its last legs. Starting was sluggish or even failed on cold mornings but the battery would stagger on with a little help. Now we have alternators that instantly replace the battery capacity used for starting, and engines that fire within one or two revolutions, the battery will show no signs of failure until the engine won't actually turn at all. Two days ago I took my wife to an appointment in Lancaster (22 miles). The car started from cold with no hint of battery problems. I waited for her in the car with the radio playing for about 20 minutes and when she returned the car failed to start. In fact the starter engaged but didn't turn the engine then the solenoid simply rattled whilst the dash lights came on and went off in time with the rattle. I was in luck in that the next car into the car park was carrying jump leads so no real problem (but a lot of luck!) and we returned home. A subsequent test once home proved the engine would start at least twice but if the headlamps were switched on they dimmed and died within a couple of minutes. So the Smart now has a new battery.
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