Alternator failure on 2004 Symbol

The alternator (probably the original) on my 2004 Symbol recently failed and I had it replaced along with a new vehicle battery. I've been keeping the vehicle battery topped up with the on-board charger, activated for a couple of hours a day. I went to use it for the first time since being returned from the garage a few miles away only to find that the brand new replacement alternator has now failed. Am I just unlucky with a faulty replacement having been fitted or could there be an underlying problem, perhaps with the on-board charger or the split charge relay? On the subject of this relay and the identical one for the fridge, I thought I might replace them anyhow but not sure how to find a perfect match.

I don't think anything on the habitation side could really stress the alternator enough to cause it to fail early - you've probably got a 20A fuse fitted and it should supply that no problem - and of course if it were to be, you could expect something to be getting pretty hot, so there's a good chance you would know about it from the hot smell!

A really knackered vehicle battery could load it a lot, but with a new battery that should not be the issue.

A friend of mine had repeated problems with failed alternators on his (white van) Boxer, and he reckoned that part of the reason was the lack of a roadwater spray shield that was meant to be fitted - and the other was just bad quality replacement parts!

Thanks, Roopert, that's reassuring. The guy at the garage remarked that it was q wet when I took it back yesterday but I had been down some rather flooded Devon lanes, although only after it had already failed. Strange that the problem has only just arisen, given the age of our van, which we've had relatively problem free since 2015. Anyhow, I'm assuming the alternator will be replaced under guarantee and we'll see what happens.

Hi

Sounds to me like a faulty new unit.   In normal use you would have to do something pretty drastic to kill an alternator in that short time. Like motors it’s running for long periods at low RPM and high current they don’t like.

Roopert wrote: you could expect something to be getting pretty hot, so there's a good chance you would know about it from the hot smell!

Agreed, a burnt-out alternator is normally obvious, windings don’t just smell they “absolutely stink” and if you look through the ventilation holes you can usually see a black mess instead of nice shiny windings.

Incidentally, the most likely time for any product to fail is when its new (or very old). When it’s new faulty materials and manufacturing faults show up and when it’s very old obviously parts wear out. It’s known as the “bathtub” curve (because a graph of failure rates against time looks like a bathtub) and is what manufactures try to flatten as much as possible.

The other thing that comes to mind is are you sure the old unit was actually faulty, or could it be a case of wrong diagnosis?

Whatever It should be sorted under guarantee.

Brod

Another thing regarding alternators, at least older tech ones, is that you can get different output ones in the same physical size. When my original one packed up some years ago, the motor factors offered me any one of three, obviously going up in price depending on output. I went for the middle one, but in hindsight should maybe have opted for the highest.
Al.