monty Posted April 7, 2019 Report Share Posted April 7, 2019 I notice various previous posts but my ammeter has just started playing up @ higher revs. Just fitted a new battery but the ammeter needle was wildly flickering fully across the gauge @ around 2500 rpm & above before the new battery & still now first day out with the new one. A normal reading after startup of around zero & up to the 2500 & then it goes mad! Running with an alternator & it seems to have started within the last 100 miles. Everything else electrical appears normal. Any ideas? Quote Link to post Share on other sites
Steves_TR6 Posted April 7, 2019 Report Share Posted April 7, 2019 Faulty alternator? Or loose earth that makes/breaks at high engine revs/engine lean angle? steve Quote Link to post Share on other sites
Lebro Posted April 7, 2019 Report Share Posted April 7, 2019 +1 for both above points Bob. Quote Link to post Share on other sites
monty Posted April 7, 2019 Author Report Share Posted April 7, 2019 Thanks for that chaps. What is the easiest way o check the alternator? Could it be a slipping fan belt? Quote Link to post Share on other sites
MRG1965 Posted April 7, 2019 Report Share Posted April 7, 2019 2 hours ago, monty said: Thanks for that chaps. What is the easiest way o check the alternator? Could it be a slipping fan belt? Hi Monty, no not slipping fan belt. Most likely the rectifier pack/voltage regulator. You don't say if it goes massively positive or negative or both. Mark Quote Link to post Share on other sites
monty Posted April 7, 2019 Author Report Share Posted April 7, 2019 20 minutes ago, MRG1965 said: Hi Monty, no not slipping fan belt. Most likely the rectifier pack/voltage regulator. You don't say if it goes massively positive or negative or both. Mark Hi Mark, Both from stop to stop! Quote Link to post Share on other sites
MRG1965 Posted April 7, 2019 Report Share Posted April 7, 2019 1 hour ago, monty said: Hi Mark, Both from stop to stop! 1 hour ago, monty said: Hi Mark, Both from stop to stop! Hi Monty, yes definitely sounds like the internal regulator. If you Google or YouTube you'll find tests and videos about testing and changing it if you feel confident or there are people out there who will either repair of a refurb one for about £50 or so. New part and your time much less. Mark Quote Link to post Share on other sites
Steves_TR6 Posted April 7, 2019 Report Share Posted April 7, 2019 I bought a new 60a alternator for about £60, has been great for a few years now. so maybe notmworth repairing ? steve Quote Link to post Share on other sites
monty Posted April 7, 2019 Author Report Share Posted April 7, 2019 So perhaps I did not need the recently purchased new battery! The old one was not starting the car after around 3 or 4 weeks not being used. Tested the battery which was showing a little weak on a couple of cells & the alternator tested & appearing it was charging ok. Maybe incorrect diagnosis by the garage? Quote Link to post Share on other sites
ctc77965o Posted April 8, 2019 Report Share Posted April 8, 2019 You can see what the alt is doing to your battery by putting a voltmeter across the battery...it should rise from 12.x to 13.8V after starting the car, and it should not exceed 14 even at 3000rpm. If it's going higher that will fry your battery, maybe enough to boil it and wreck your bulkhead with acid...certainly will kill one cell. Your friendly autoelectical rebuilder will be able to make it nice again. Quote Link to post Share on other sites
MRG1965 Posted April 8, 2019 Report Share Posted April 8, 2019 Agreed, previous battery may have been fatally damaged by a faulty alternator, if it were pushing too much voltage as the ammeter would not have indicate that. Mark Quote Link to post Share on other sites
Lebro Posted April 8, 2019 Report Share Posted April 8, 2019 Absolut. max on charge voltage for lead acid is 15V most alternators limit around 14.6V Bob Quote Link to post Share on other sites
monty Posted April 8, 2019 Author Report Share Posted April 8, 2019 So next question is what unit do I buy & from where, avoiding the usual Chinese etc stuff? Quote Link to post Share on other sites
MRG1965 Posted April 8, 2019 Report Share Posted April 8, 2019 7 minutes ago, monty said: So next question is what unit do I buy & from where, avoiding the usual Chinese etc stuff? Well, if you can't find a local repair shop and you do go for a new unit be careful on the output as some have quite high outputs compared to what the wiring harness was designed for with a dynamo, unless you upgrade the wiring. And even the expensive stuff can be poor quality. I've stopped buying new items as I throw more away when they fail than last more than a year or so. If your current unit has provided a long life, then repair might be the better option. I'm sure there are many people on the forum who can provide references for people in your area. Mark Quote Link to post Share on other sites
monty Posted April 10, 2019 Author Report Share Posted April 10, 2019 On 7 April 2019 at 8:54 PM, Steves_TR6 said: I bought a new 60a alternator for about £60, has been great for a few years now. so maybe notmworth repairing ? steve From where Steve? Quote Link to post Share on other sites
Steves_TR6 Posted April 10, 2019 Report Share Posted April 10, 2019 16 minutes ago, monty said: From where Steve? On ebay from Midland Sports and classics as screenshot I paid about £43 inc postage so they’ve put the price up a little ! Quote Link to post Share on other sites
monty Posted April 10, 2019 Author Report Share Posted April 10, 2019 4 hours ago, Steves_TR6 said: On ebay from Midland Sports and classics as screenshot I paid about £43 inc postage so they’ve put the price up a little ! Thanks Steve. Same part number as the Moss offering so I assume it is the same Chinese 'Lucas' type repro. Do I take a chance or spend much more on a more modern quality unit! Decisions, decisions! Quote Link to post Share on other sites
Steves_TR6 Posted April 10, 2019 Report Share Posted April 10, 2019 Mine has been reliable Monty, not all Chinese stuff is shoddy! Quote Link to post Share on other sites
monty Posted April 11, 2019 Author Report Share Posted April 11, 2019 17 hours ago, Steves_TR6 said: Mine has been reliable Monty, not all Chinese stuff is shoddy! 17 hours ago, Steves_TR6 said: Mine has been reliable Monty, not all Chinese stuff is shoddy! Yes you are right Steve! One of my hobbies is model railways where nearly everything is Chinese excellent quality. Unfortunately when it comes to TR's I have suffered several instances of Chinese shoddy. Anyway I now have a new non-Chinese alternator coming from Halls Electrical. A bit more expensive but hopefully reasonable quality. Thanks for your input. Quote Link to post Share on other sites
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