YOW500 Posted February 14, 2021 Report Share Posted February 14, 2021 Hi everyone. My TR3a was fitted with an alternator years ago by a TR workshop, with no issues. On a recent start up, and short run, the gauge is showing 30amps plus, at anything over 2000 rpm. This only reduces if the lights, etc, are turned on. There must be a problem?. Help would be much appreciated. Russell. PS I'm rubbish with electrics, please keep it simple if possible. LOL Quote Link to post Share on other sites
RobH Posted February 14, 2021 Report Share Posted February 14, 2021 If connected correctly the ammeter only shows current flowing into or out of the battery. If the ammeter is telling the truth then either your battery must be very low on voltage - perhaps it is very discharged or is failing - or (less likely) the alternator is producing too much voltage. Do you have a spare battery you could try using? If the fault disappears then it is a battery problem. There isn't much to go wrong with the ammeter, it is more likely to read low or not at all rather than to give an erroneous high reading. To check it, with the engine off turn on the headlights. The ammeter should show a discharge of about 10 Amps. If the reading is much different the meter may be faulty. (This is assuming you do not have LED headlamp bulbs) If you have access to a voltmeter you can read the voltage across the battery terminals. It should be about 12.5 to 12.8V with the engine off. If it is much below that the battery may be faulty or very discharged. Next measure it again with the engine running at 2000 rpm or more. Usually it will read somewhere between 14.2 to 14.5 volts. If the voltage is higher than 14.7 the alternator may be faulty. Quote Link to post Share on other sites
YOW500 Posted February 14, 2021 Author Report Share Posted February 14, 2021 Rob, PM sent, Russ Quote Link to post Share on other sites
Lebro Posted February 14, 2021 Report Share Posted February 14, 2021 Agree with all above. Bob. Quote Link to post Share on other sites
Ian Vincent Posted February 14, 2021 Report Share Posted February 14, 2021 A few years ago I allowed my battery to go flat and after getting a jump start it took a good few miles (and I mean twenty or thirty) for the charging rate to drop. Rgds Ian Quote Link to post Share on other sites
jpmf Posted February 14, 2021 Report Share Posted February 14, 2021 After starting my 6 with a flat battery after it's rebuild the high output alternator some PO had fitted put too much charge through ammeter and cooked it. I had the workings of a modern 60amp ammeter fitted on to the face of my original. Quote Link to post Share on other sites
YOW500 Posted February 16, 2021 Author Report Share Posted February 16, 2021 Rob and Bob. To thank you for taking the time to respond. The alternator was the issue. Testing in the way Rob suggested gave a result of 17.5 volts at the battery, at 2000rpm, Wow!!!. Replacement alternator solved the issue. Just as aside I have an original alternator with a keyway, and allen key centre to aid the removal of the holding nut, a more modern type with just a keyway, and the final up to date type with no allen head, and no key way. Thats progress for you, LOL. Russell Quote Link to post Share on other sites
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