Nostalgiajohn Posted March 29, 2023 Report Share Posted March 29, 2023 Hi all, As I continue to upgrade my TR3A (TR4 Engined) and having now got a Dynalite to replace the now defunct dynamo, I realise that the Amp Gauge is unsuitable due to the Dynalite's output. Consequently I will need a Volt Meter. The slight issue I have is that I have purchased a fully restored set of instruments with magnolia faces which I think will look great against the red leather dash/trim. I can't seem to find a matching jaeger volt meter and unless I am advised differently, I suspect I may have to go for a smiths alternative, but likely a different shade of magnolia, or go for an off the wall led 'option'. Any advice from members much appreciated. John Quote Link to post Share on other sites
RobH Posted March 29, 2023 Report Share Posted March 29, 2023 The ammeter will be fine with the Dynalite John, provided it is wired up as standard. The ammeter is only intended to indicate charge going into and out of the battery and that will not really change even though the Dynalite can provide more current than the old dynamo could, as it is a function of the battery rather than of the generator. In normal circumstances it really only indicates significant current during re-charging immediately after starting. In fact the ammeter is a fairly crude and robust device and will not mind much even if it gets 'pegged' momentarily if you run the battery very low from extended cranking. Quote Link to post Share on other sites
Lebro Posted March 29, 2023 Report Share Posted March 29, 2023 (edited) The ammeter is perfectly suitable for use with the alternator, how much current do you think it will be putting into the battery ? The only time a large current will be flowing through it is immediately after start up, & that will only last a few seconds, & won't do the ammeter any harm. Bob Rob beat me to it ! Edited March 29, 2023 by Lebro Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 29, 2023 Report Share Posted March 29, 2023 (edited) Do you have an accessory type cigarette lighter socket? I have a plug into the cigarette socket led volt meter with USB outlet on my car. Not pretty but functional. The rest of the gauges are ordinary black faced ones. My car has a small 40 amp Nippon Denso alternator from Racetorations. https://www.racetorations.co.uk/product/lightweight-40a-universal-alternator/ Less than a fiver gets a basic plug in volt meter that will tell you what ever you are after volts wise. https://www.ebay.co.uk/itm/12V-24V-Car-Cigarette-Socket-LED-Voltmeter-Voltage-Battery-Tester-Detector-Meter/354455611774?_trkparms=amclksrc=ITM&aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=247311&meid=8eef56ace7d4461cac546bde097160f9&pid=101195&rk=2&rkt=12&sd=385497648470&itm=354455611774&pmt=1&noa=0&pg=2047675&algv=SimplAMLv11WebTrimmedV3MskuWithLambda85KnnRecallV1V4V6ItemNrtInQueryAndCassiniVisualRankerAndBertRecallCPCBlended&brand=Unbranded&_trksid=p2047675.c101195.m1851&amdata=cksum:3544556117748eef56ace7d4461cac546bde097160f9|enc:AQAHAAABUMzHrtmBs5dQ/HIG5+RfYnxi7NXGqhNmkIynG8/JUFU8mFH0LR4rYiCzTE7ooZG50CTrFa800zEyCYXzaLce6aP2sNHYQFVEwDm5p/Luk/SeZYJ4KDvPkFH59OJf3XeGeYKecqqQTdGEPj5LqiOXakXkA7wAROR6SvBMgDgTi/+8IIGXGY+Di+q8Wx/O7wl+4ZOrCXCNHdMZzZcCKDbRXieDNxVoHo8iAl+CRWa7CoOiivZIztrh49ZnfC21RT+cwnw/8me6NE1lcBhWd6LGLGDSUfmaLFGC8MMArL0vNVlyAy23LkdZr3V9QykaU6XxohtwwOqQvl/FNv1LRnFTF+t3fk/PjzHNCfSnyueGQ7i97OzqJoDaO5FD7xQ7f4KFizmmrJtgeTMOUa0v5q0CYA1CviWP5fLY7mVDkDbFWHujE+ZC9h7lVkpN0ZZ9vbUDeQ==|ampid:PL_CLK|clp:2047675&pageci=f012205d-a239-4c6d-a643-92b9f91af128&redirect=mobile Edited March 29, 2023 by BlueTR3A-5EKT Quote Link to post Share on other sites
stuart Posted March 30, 2023 Report Share Posted March 30, 2023 FWIW I dont think there is a Jaeger voltmeter that would look anything like it anyway Also they never fitted Jaeger ammeters either to TRs Stuart. Quote Link to post Share on other sites
Mastaphixa Posted March 30, 2023 Report Share Posted March 30, 2023 If your concerned about the initial needle swing on start up pegging the meter, you could install a shunt across the terminals. The ones I've seen are 3 1/2" of 16 ga wire. It's supposed to cut the needle swing in 1/2 or there abouts. Steve Baker Quote Link to post Share on other sites
Lebro Posted March 30, 2023 Report Share Posted March 30, 2023 There really is no need to worry, I have had an alternator fitted for the past 10 years, both with a good battery, & a knackered one, I have never seen the ammeter hit the end stop. Bob Quote Link to post Share on other sites
ianc Posted March 31, 2023 Report Share Posted March 31, 2023 I have had an alternator fitted for 30 years and, like Bob, have never seen the ammeter hit the end of range (30 amps). Even were it to get there, it would be for a very limited duration and, as Bob states, these ammeters are very robust and can stand this treatment. Ian Cornish Quote Link to post Share on other sites
Ralph Whitaker Posted March 31, 2023 Report Share Posted March 31, 2023 As above do not worry. I deliberately chose a 15ACR alternator as that is only rated at 36amps in deference to the 30amp ammeter in the car, but I have only ever seen it flick up to around 20amp immediately after starting the car and soon drops back. Ralph Quote Link to post Share on other sites
Ian Vincent Posted March 31, 2023 Report Share Posted March 31, 2023 (edited) I have a 40 amp Nippon Denso alternator and a conventionally wired ammeter (i.e. without a bridge) and it has never been a problem even when I have on occasions allowed the battery to go flat. Rgds Ian PS As a belt and braces precaution I have a 40 amp fuse in line with it. Edited March 31, 2023 by Ian Vincent Quote Link to post Share on other sites
Nigel C Posted March 31, 2023 Report Share Posted March 31, 2023 11 hours ago, Ian Vincent said: I have a 40 amp Nippon Denso alternator and a conventionally wired ammeter (i.e. without a bridge) and it has never been a problem even when I have on occasions allowed the battery to go flat. Rgds Ian PS As a belt and braces precaution I have a 40 amp fuse in line with it. the fuse is a must, as I found to my cost in the outside lane of the A40 (Target Island area) at 10pm one night. Very loud bang, everything went dark and I was hit by the dial glass that shattered when the alternator failed and dumped "a lot of juice " through the system! Quote Link to post Share on other sites
lindatr4 Posted June 19, 2023 Report Share Posted June 19, 2023 Fitted a 45amp alternator 4 years ago and have had no problems until this last weekend. Poodling along quite happily when suddenly the engine died. I glanced down to the ammeter (original 30-0-30) to see black smoke behind the glass and the beginnings of a small fire starting! I coasted along to find a safe place when suddenly the engine fired back to life. The glass and small fire cleared but now of course there is no charge going to battery. The gauge does register a discharge when lights are on but nothing from the alternator to compensate. Is this a matter of "getting away with it" for 4 years or the age of the 60 year old ammeter? Quote Link to post Share on other sites
brian-nz Posted June 19, 2023 Report Share Posted June 19, 2023 Hi All This topic is timely, as I took the TR3 to upholsters this morning. On the way home (only about 5 km) I noticed the ammeter needle at the far right. This has not gone back to 0 and appears stuck. I am baffled as to why this has happened. I have run an alternator for past 10 years . Should I take the gauge apart and see if needle is stuck or is there something more I should be worried about Regards Brian Quote Link to post Share on other sites
RobH Posted June 19, 2023 Report Share Posted June 19, 2023 If it doesn't return to zero when you switch off, just give it a tap Brian - likely it is just the needle stuck. the inner workings are very simple - to the point of crudeness and it is possible for the mechanism to get caught up. It has happened to others on here. If that doesn't work it is easy to take the thing apart to free it off. On the other hand, if it does return to zero when you switch off it is probably a problem with the voltage regulator in the alternator, which would need sorting before you destroy the battery. Quote Link to post Share on other sites
RobH Posted June 19, 2023 Report Share Posted June 19, 2023 (edited) 1 hour ago, lindatr4 said: Fitted a 45amp alternator 4 years ago and have had no problems until this last weekend. Poodling along quite happily when suddenly the engine died. I glanced down to the ammeter (original 30-0-30) to see black smoke behind the glass and the beginnings of a small fire starting! I coasted along to find a safe place when suddenly the engine fired back to life. The glass and small fire cleared but now of course there is no charge going to battery. The gauge does register a discharge when lights are on but nothing from the alternator to compensate. Is this a matter of "getting away with it" for 4 years or the age of the 60 year old ammeter? This is odd. If the ammeter still registers a discharge for the lights it must be working OK. First thought was that maybe the current loop had become unsoldered and had shorted to the case but that cannot be if it still works - though a remote possibility is that it has somehow burnt off the short circuit and is working through a very iffy connection. Current must be going through it to work the ignition. Also the lighting pick-off is from the alternator end of the ammeter so that connection must be OK too. You obviously need to pull the thing out to examine the internals and the connections. It sounds as though either the alternator connection is no more, or the alternator isn't generating now. If it has been feeding into a short circuit the rectifier stack will not have been happy about that. The ammeter will look something like this inside. That loop of thick wire carries the current and if the solder gives way it might touch the case, resulting in a short circuit. (As explained several times before, just because the alternator can supply 45A doesn't mean it does. The charging current is likely no different than with a lesser one as it is determined by the state of charge of the battery. The 30A ammeter won't really care as the peak current is only there for a very short while.) Edited June 19, 2023 by RobH Quote Link to post Share on other sites
RogerH Posted June 19, 2023 Report Share Posted June 19, 2023 Hi Linda, interesting the the engine stopped firing, then started again. The ammeter shouldn't get in the way. You need to take the ammeter out, open it up and see what has gone phut. As mentioned above, there is a thick copper wire soldered to the pins. Easy fix if you can open it. I wonder what the fire was !!!! Roger Quote Link to post Share on other sites
Z320 Posted June 19, 2023 Report Share Posted June 19, 2023 If the ammeter always indicates a battery load often any electric consumer has been connected directly to the battery. The needed current is shown as a load, the ammeter doesn’t know it’s not doing to the battery. Apart from that I like this thread and all answers, on other forums I had to read too much self knitted problems about „the need“ to modify the ammeter. Quote Link to post Share on other sites
RobH Posted June 19, 2023 Report Share Posted June 19, 2023 43 minutes ago, Z320 said: If the ammeter always indicates a battery load often any electric consumer has been connected directly to the battery. In that case the current is shown as a 'charge' when the generator is running and will not register on the ammeter if it is not. On a correctly wired system it will show as a discharge when the generator is not running and will not register when it is. In Linda's case apparently it does show a discharge with the generator not working so things must be wired correctly. Quote Link to post Share on other sites
Z320 Posted June 19, 2023 Report Share Posted June 19, 2023 With a discharge while everything is switched off I would disconnect the battery. If it still shows the same discharge —-> this is her zero, If it raises up to zero with the battery disconnected there is an unexpected consumer on board Quote Link to post Share on other sites
RobH Posted June 19, 2023 Report Share Posted June 19, 2023 19 minutes ago, Z320 said: With a discharge while everything is switched off I would disconnect the battery. If it still shows the same discharge —-> this is her zero, If it raises up to zero with the battery disconnected there is an unexpected consumer on board What you are saying is correct Marco but from the description of the fault, that is not what is happening here. We have not been told there is a continuous discharge shown when everything is switched off. If the engine isn't running or if the generator isn't working there will be a discharge indicated whenever you turn the lights on, which is exactly what Linda says. "The gauge does register a discharge when lights are on...." Quote Link to post Share on other sites
Z320 Posted June 19, 2023 Report Share Posted June 19, 2023 Sorry, I should read better Quote Link to post Share on other sites
lindatr4 Posted June 22, 2023 Report Share Posted June 22, 2023 (edited) Dismantled it today and found evidence of burning. Beginning to think that there is some gravity in the advice that the 30-0-30 gauge is not man enough to handle modern alternators Edited June 22, 2023 by lindatr4 Quote Link to post Share on other sites
RobH Posted June 22, 2023 Report Share Posted June 22, 2023 'Sigh' - once again. The ammeter should only register the current going into and out of the battery. Changing an alternator for one with more current capability MAKES NO DIFFERENCE to that current. The alternator may be capable of providing more but the charge current drawn through the ammeter is determined solely by the battery which (provided it is in good shape) will NOT draw any more current than it did before. If the battery is in a very low state of charge after prolonged cranking it might draw a bit more but all that will do is 'peg' the needle against the end-stop for a few seconds during the peak . I think your burning is likely to be the result of a short-circuit somewhere. Certainly the left-hand connector in that photo has got very hot. Quote Link to post Share on other sites
Lebro Posted June 22, 2023 Report Share Posted June 22, 2023 +1 Bob Quote Link to post Share on other sites
ianc Posted June 23, 2023 Report Share Posted June 23, 2023 +2 The 30-0-30 is a tough little beast and can withstand a short duration flow of slightly more than 30 amps, which is likely to be very rarely seen (if ever - I haven't in 30 years with my alternator). Ian Cornish Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.