Lucas Alternator is Overcharging--What Now?

The TR6 developed an over-charging problem, with the volt meter indicating in the red (about 16-17 volts). This can damage the ignition components as well as other electrics, including the battery. In this video, we talk about the basics of an alternator and how it's wired on these cars, quickly review options for repair vs. replacement, and remove the malfunctioning alternator from our Triumph TR6. This will be largely the same for other Triumphs (such as a Spitfire, GT6, etc) as well as most other classic cars using a Lucas alternator.

[@amandasettee8922]

great explanations

[@midwestmotoring]

Glad it was helpful!

[@MGB-learning]

Great video. Thanks

[@midwestmotoring]

Thank you too!

[@jamcdona]

Ha! I have a degree in Electrical Engineering Technology, and you are good with your explainationions LOL. What is the component of the alternator that can cause a battery drain? I've always wanted to know that. My money is on a sensing wire backing out of the plug? Bane of my existance on my Bosch wired Alfa, I've found 3 that had come out on different sensors. PITA to diagnose.

[@midwestmotoring]

With British cars, who knows? I've got a battery drain on the Spitfire that I've never been able to track down. I hadn't thought to check if it was the alternator.... Honestly I always install a kill switch on all of the classics so it's never a problem.

[@anthonynicholls8010]

👍👍

[@midwestmotoring]

Thanks!

[@jamcdona]

Hi, is there any chance that you are going to make a Lucas 'refurb' video? I have a feeling mine is on it's way out, and it might be easier to replace the diode pack or whatever else than to get another. Most available- Rockauto!- do not come with fan or pully, and I'm not sure I want to swap those over. I could see one or another not fitting the new alternator, 'cause Murphy's law of aftermarket. Last week I pulled my 74 out of storage and drove 45mins to home, stopping at the store. I left the parking lights on, and in 15mins the battery was stone dead. I uber'd the battery home, charged it, and uber'd back. Once I got home I verified that the alt. was only putting out 12.x Volts. Yesterday I unplugged the connector, checked leads, plugged it back in to check for ripple and hook up my alt. tester. It was working fine with 14.2V...irritating. I'm going to drive it today to see if it's heat related. Or, it could have been in the plastic connector...I've never taken it off in 6yrs of ownership.

[@midwestmotoring]

I've thought about it, but rebuilding alternators requires some soldering skills and diagnostic skills that might not translate through a video. Also I'd be bad at it since it's not my area of expertise. Diagnosing is easier than fixing....

[@jamcdona]

@@midwestmotoring Thanks for the reply. I've since bought a reman'd Bosch unit that works a treat. My Lucas was indeed shot, but put out 14V, until you had lights on then it couldn't charge the battery. Bat light never came on...

[@kevinmcguire3715]

Prince o'darkness strike again.

[@midwestmotoring]

To be fair, most of the time that Lucas electrics fail, the system is several decades old. It's typically down to lack of maintenance... at least unless you have a TR7. Those were never screwed together properly at the factory....