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[Entwood]

Replaced the battery yesterday, its been messing about a tad for a week or so, now won't hold enough charge after 36 hours to start the car .. can't complain, I've had the car 5 years and it's the same battery, I think it might even be the original.

I have a digital voltmeter wired in so I can monitor voltages when towing, it has enabled me to watch the old battery slowly dying ......

The oddity ...   

All appears to be normal voltage wise, 12.7v not running; 14.4v for about 20 minutes after starting then drops to 13.8v; with headlights, aircon, heated rear screen, wipers all on it sits at 13.6v which seems to show the alternator is working fine .....

The oddity appears on switch off... as the engine winds down the battery light illuminates which is a fairly common occurrence on many cars .. but once the engine is STATIONARY the battery light either remains on steady for about 9 seconds, or slowly cycles on/off at 1-2 secs intervals for about 9 seconds...

Now I had similar some time back after the alternator was changed, and it suddenly stopped doing it, I seem to remember mentioning it here but I can't find the post where the causes were postulated, any electric/electronic wizkids any thoughts

[Kevin Wood]

As I said before, I believe, it must be the voltage regulator trying to tell you something. They are quite intelligent these days. Output voltage is temperature controlled, as you have observed, giving a highish voltage after a cold start to bulk charge the battery, settling to a float charge rate after a while.

The problem is, I've not been able to find any indications online as to what a flashing light might indicate.   

You have a voltmeter, and, as you say, it appears to be behaving itself so I'd just keep an eye on it for now.

[Andy H]

The regulator failed in my alternator last year. I found a pattern regulator in stock at an old school alternator/starter motor rebuild shop and fitted that (though I would have preferred to fit genuine). I never noticed any strange behaviour before the genuine regulator failed.

I get random morse code from the battery warning light almost every time I switch the engine off now. There doesn't seem to be any problem with the charging (I have checked the voltages).

I think your flashing light is simply evidence that you have a pattern voltage regulator in your refurbished alternator. I have no idea why it stopped doing it for a while though