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Voltages from Lucas alternator

Posted: Sat Apr 26, 2025 1:52 pm
by Wes
Had issues with PO fitted Lucas Alternator at least 50,000 miles ago. So brushes replaced, rectifier replaced, alternator refitted. All warning lights go out and stay out on start up :-)

Thought I'd just check the voltage at the battery. 12.4V before start up, 14.2V on idle but rev the engine and it peaks at 17.4V. Guessing this isnt good?

Re: Voltages from Lucas alternator

Posted: Sat Apr 26, 2025 4:28 pm
by svenedin
I don't really understand alternators but they have a built in voltage regulator unlike the external regulator with a dynamo. Clearly that voltage regulator is not working. Given the PO's incompetence behind the dashboard, are you sure the alternator is wired up properly? If the alternator is giving an unregulated charge to the battery it will overcharge and damage it........


Stephen

Re: Voltages from Lucas alternator

Posted: Sat Apr 26, 2025 5:16 pm
by Wes
Ive replaced all this so assumed that at least some of this was the regulator? :-(