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Demise of the ammeter

Discussion in 'Norton Commando Motorcycles (Classic)' started by crusadersports, Mar 24, 2020.

  1. Onder

    Onder

    Joined:
    May 11, 2010
    I go with a digital voltmeter on all my bikes. Cheap and easy to wire. Ammeter seems to flog itself uselessly most of the time.
     
  2. MexicoMike

    MexicoMike

    Joined:
    Jan 31, 2010
    A warning light pretty much shows you the same thing as an ammeter for casual observation...it's charging/it's not charging. What else do you need to know while out riding? In the shop for diagnostics, nobody would use the factory ammeter to make an accurate determination of what's happening - they'd attach a dedicated meter. Also, all the electrical power has to go through the ammeter - another connection/device to fail. Looks cool though... ;)
     
  3. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    A warning light tells you the alternator is putting out voltage. That doesn't mean the battery is charging.
     
  4. ludwig

    ludwig

    Joined:
    Aug 30, 2006
    On my N15 I changed the ammeter for a clock and added a USB port with a voltmeter for my GPS.
    More useful for touring.

    [​IMG]
     
  5. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Is the 12 hour clock face so you can measure the 0-60 time Ludwig ?? ;)

    On a more serious note, where did you get the voltmeter / USB from and are they reliable?
     
  6. ludwig

    ludwig

    Joined:
    Aug 30, 2006
    They are easy to find on the internet.
    I only have it for 2-3 years, but it seems reliable, even in heavy rain (cap closed)
    With the cap closed, you can still read the voltage.

    [​IMG]
     
    Last edited: Mar 25, 2020
    Fast Eddie likes this.
  7. zotz

    zotz

    Joined:
    Jul 15, 2007
    I've also had one fail. Puts the whole bike down. I run a volt meter now.
     
  8. ntst8

    ntst8 VIP MEMBER

    Joined:
    Feb 14, 2004
    An upgrade waiting to happen. New “genuine” ammeter was rubbish out of the box.
    76AE5B21-CABA-4C7A-B26C-E472EC16C15D.jpeg
     
  9. motorson

    motorson VIP MEMBER

    Joined:
    Nov 29, 2011
    A long time ago an electrical engineer said to me, "you can know a lot more about a battery and a charging system by it's voltage than you can with an amp meter." He was right of course. Now I don't really care how much amperage a charging system is putting out as long as the total voltage of the system arrives at the prescribed 13.6 volts or better. Say you have a bad charging system that will only put out 9 volts. It would still swing an amp meter to the positive side as long as the battery is below 9 volts. But the main benefit of using a volt meter and learning what it means to each component of the whole system is that you do not need a big wire carrying the charging current way up in the headlight!
     
  10. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I think the demise of the ammeter, in more general use, is simply that electrical charging system reliability improved, so it was not something riders invested huge interest in anymore.

    However they did still want to know if there was an issue, hence the warning light.

    If all is working = no light = don’t think about it.

    If there’s a problem = light = investigate.
     
  11. DevonNorton

    DevonNorton VIP MEMBER

    Joined:
    May 7, 2015
    This thread reminded me of a lovely story in the old Motorcycle Sport magazine.
    I can't recall all the details but the rider of an old British bike with no speedometer reported that he was doing 2 Amps heading over a particular hill.
    This was the only measure he had of the bike's performance.
    Well it made me laugh.
    Andy
     
    motorson, baz and Fast Eddie like this.
  12. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    They fitted an ammeter because people used to worry about charging and it was a bit of a relic of 1930s vehicles with high/low charge switches.

    The ammeter looks like it would be cheaper to make than a voltmeter, back then. The ammeter only has a few twists of thick wire as a coil.

    They could have put a charge warning light on two-brush dynamo systems, but then it would need a switch as well.
     
  13. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    I'm an electrical engineer, and I disagree with that statement. A voltmeter only tells you that the alternator is working, not if the battery is charging. Read my post # 10 here.

    My brother had a 1981 Lincoln Continental MK VI, a high end luxury car in its time - it came with an ammeter, not a voltmeter.
     
    Last edited: Mar 26, 2020
  14. Danno

    Danno

    Joined:
    Feb 7, 2010
    It took a while, but I finally found a 2" positive-ground Lucas ammeter for the SS clone. I think it came from an old Jag. I tried the repro 1 1/2" ammeters but they were crap and didn't last a week.

    [​IMG]
     
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  15. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    And a voltmeter is a few more twists of smaller wire. All analog meters are current meters, a voltmeter measures milliamps converted to volts by use of a series resistor. 1 milliamp through 10000 ohms is 10 volts.

    It's the installation costs that drove the ammeter's demise. They need either long runs of heavy gauge wire, or a current sensing resistor called a shunt.

    The final straw for the ammeter came in the 80's with digital instruments. There is no "ammeter on a chip".
     
  16. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I use an Indian Enfield ammeter in my Triton. One of the few well-made parts on a Madras 350. It has lasted for ages in a rubber mounted headlight.

    I’m not saying it’s better than a voltmeter or a voltage LED or a warning light! If the battery suddenly became isolated from everything except the brake light, I’d suspect the ammeter.
     
  17. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Well you’re no fun to argue with are you...?!
     
  18. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I’m not even saying the ammeter is better than revving up off idle and seeing if the headlight gets brighter!
     
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  19. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    It doesn’t have to be a “positive earth ammeter.”
     
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  20. motorson

    motorson VIP MEMBER

    Joined:
    Nov 29, 2011
    You gave an example of when an amp meter would tell you more than a volt meter. (ie: Sulfated cell drawing more current) I believe I can know if the charging system is working by voltage because a 12v battery will drop to 12.5v with no alternator and I am seeing 13.6 while running. Also, I can know if I have a shorted or sulfated cell by the voltage after shut down. If I see less than 12.5 or whatever I am used to seeing with no alternator then I know something is wrong with the battery. I agreed with every thing you said in post #10. And, I have wished before that I could have both meters on a system. In my mind I think I can deduce more from a volt meter than I can from an amp meter though.
     

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