Ammeter and Alternator compatible?

Discussion in 'General IH Tech' started by gcluke, Jun 12, 2018.


  1. gcluke

    gcluke Farmall Cub

    Joined:
    Sep 5, 2014
    Messages:
    46
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Long Beach, CA
    I swapped a 345 from a 73 scout into my 66 Travelall and am installing a Painless universal wiring kit. Can I still run the original ammeter safely. The Painless directions are telling me to run a wire that originates in the fuse panel to the neg side of the ammeter then run from the positive side to a maxi fuse and terminate at the starter solenoid B+. Painless instructions have warnings about amperage. So 2 rookie questions. What would be the amperage rating for the 66 Travelall ammeter versus probable amperage for 73 Scout alternator. And which side is positive and neg on the gauge





    Sent from my iPhone using Tapatalk
     
  2. MrKenmore

    MrKenmore High Wheeler

    Joined:
    May 19, 2013
    Messages:
    1,689
    Likes Received:
    245
    Trophy Points:
    63
    Location:
    Long Island, NY
    I think the stock Scout 2 10SI alternator was 37 amp output. I am sure that you don't have the original in there and the remanufactured ones became standardized at around 60 amps. I am not certain of the ammeter rating but safely assume many Scouts were driving around with the stock wiring and 60 amp remanufactured alternators. I would ditch the ammeter especially if you are going through all the effort to rewire the truck. I did the same on my Terra. There are other considerations when wiring in "ammeter mode". Your battery 12V+ would go to the starter solenoid. The ammeter wire would go as you described. The big lug on the alternator goes back to the other ammeter post and also provides the primary feed to the fuse panel.
     
  3. kevingweq

    kevingweq High Wheeler

    Joined:
    Nov 1, 2013
    Messages:
    2,732
    Likes Received:
    447
    Trophy Points:
    83
    Location:
    Sudbury Mass
    You could upgrade your ammeter to a 60 amp unit


    IHS1837 ammeter ih.jpg
     
  4. RBS

    RBS Farmall Cub

    Joined:
    Jul 31, 2008
    Messages:
    72
    Likes Received:
    4
    Trophy Points:
    8
    Location:
    Normal, IL
    You will probably find the terminals on your ammeter are marked with an I and a B. The B (or battery) would correspond to what your wiring harness is calling positive and the I (ignition) would be negative. Basically the battery and starter motor are on one side of the meter (because you cannot pull starter current through an ammeter) and the alternator and everything else is on the other. So when in discharge current is flowing from the battery through the ammeter to the vehicle circuits other than the starter motor and in charge mode current is flowing from the alternator through the ammeter and back to the battery.

    If you hook up the terminals backwards it won't hurt anything, the gauge will just read backwards showing charge when there is actually a discharge.

    An ammeter provides a nice measurement of whether the battery is charging or discharging and also the rate but the downside is the full alternator current is flowing through this gauge and its associated wiring so it was more practical to read system voltage, which gives you a clue to discharge/charge activity, rather than use an ammeter. The wiring to the ammeter and the movement itself must be able to withstand the full alternator output without excessive voltage drop. If the gauge itself is the only issue a shunt can be installed in parallel with it so that part of the current flows through the gauge and the rest flows through the shunt.
     
    gcluke likes this.
  5. Greg R

    Greg R Dreams of Cub Cadets

    Joined:
    Mar 23, 2002
    Messages:
    4,178
    Likes Received:
    272
    Trophy Points:
    83
    Location:
    Lebanon, OR
    The only time "full" current is going through the ammeter exits in possibly two scenerios. A dead or low battery will pull a high charge current which can approach an alternator's rated output, or a high current draw on the load side with an underrated or defective alternator and the system is using full battery output. Other than that, the alternator only puts out what's needed so if it and the system is up to snuff the most the ammeter sees is a moderate charge current which puts the needle mid to slight charge indication, or whatever current draw there is with the engine off and you're running some accessories which will show as D or discharge. Put heavy loads such as winching on the battery side. The biggest problem I see with ammeters across different makes is weakening connections which leads to heat and failure. How many Chryslers or GMs have we seen with melted and sinking plastic trim ammeters in the dash? Good copper connections kept tight and maybe a dab of terminal spray will limit or prevent corrosion and heat.

    I know the older round ammeters for the 800 Scouts and Travelalls are good for about 30-35 amps. The shunt idea is a good one for higher registering, but then low currents for charging aren't indicated as good because the "calibration" has been bumped up.
     
    Last edited: Jun 13, 2018
  6. MrKenmore

    MrKenmore High Wheeler

    Joined:
    May 19, 2013
    Messages:
    1,689
    Likes Received:
    245
    Trophy Points:
    63
    Location:
    Long Island, NY
    Greg-
    Wouldn't you be imposing greater loads through the ammeter by coming off the battery? Power not available in the battery would need to supplemented by the alternator (through the ammeter). I would think you'd want it the other way around where the heavy loads were fed from alternator first.
     
  7. Greg R

    Greg R Dreams of Cub Cadets

    Joined:
    Mar 23, 2002
    Messages:
    4,178
    Likes Received:
    272
    Trophy Points:
    83
    Location:
    Lebanon, OR
    A good battery in an electrical system is similar to an accumulator in hydraulics. When there's an immediate high current draw, the battery has the better potential and will supply the amps with a moderate dip in voltage depending on it's size or capacity. The alternator responds to voltage; the more the deviation from it's setpoint, ( say 13.5-14.2) the more it puts out depending on speed or rpm. If the battery stays up to snuff, and accounting for duty cycling or allowing the winch motor to cool, the charging current to maintain the battery should not be too high if the battery can hold a good voltage. This brings up preparing your rig for winching; and the first step is considering battery capacity such as cranking amps and RC or reserve capacity. The only time I had an ammeter get warm or worried me was when the battery, for whatever reason, got low and needed high charging amps that made the ammeter go full scale for 5 or so minutes.

    The other thing is not all winching is with the engine running, and while 50-60 amps for a short pull won't dent the battery, it sure can cook a 35 amp ammeter in short order. I am pitching here for a stock system with few changes made. If there is more serious heavy duty work expected, then heavier hardware with heavier wiring should be layed out.
     
  8. gcluke

    gcluke Farmall Cub

    Joined:
    Sep 5, 2014
    Messages:
    46
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Long Beach, CA
    Thanks for all the responses. Unfortunately they are flying way over my head. I don’t plan on running any accessories beyond stock. I would like to keep the original ammeter for looks. But not if it’s going to be a safety issue. Any idea if someone could rebuild it for higher amperage. It’s this one[​IMG]


    Sent from my iPhone using Tapatalk
     
  9. Greg R

    Greg R Dreams of Cub Cadets

    Joined:
    Mar 23, 2002
    Messages:
    4,178
    Likes Received:
    272
    Trophy Points:
    83
    Location:
    Lebanon, OR
    Go to an automotive electric shop, (not stereos or security systems), someone who rebuilds generators, alternators and knows tractors and trucks; and with the gauge in hand, ask for some advice on making a bigger shunt for it. Shunts are just the copper bar across that back connecting the terminals. Then buy something like connectors or a can of something for their time and expertise.

    Other than that; a nice VDO brand voltmeter will look very nice, be accurate, and no more worries about amp draw cooking a gauge.
     
    gcluke likes this.
  10. Dana Strong

    Dana Strong Y-Block King

    Joined:
    Apr 4, 2008
    Messages:
    3,672
    Likes Received:
    509
    Trophy Points:
    113
    Location:
    Sunnyvale, Ca.
    When winching heavy loads for long distances, most electric winches need to be operated intermittently so as to allow heat to dissipate. The engine can be run constantly at a lower speed to regulate the maximum amount of current generated by the alternator and not fry the ammeter, but still keeping up with the winch draw. If the situation frequently required higher charging for long periods, a switchable line going directly from the alternator to the battery could be installed (bypassing the meter), but it would bring other possible problems.
    The alternator shunt could also be switchable, thus giving two meter ranges. The problem gets to be when one has so many extra switches and forgets which does what after the labels fade or fall off...
     
  11. MrKenmore

    MrKenmore High Wheeler

    Joined:
    May 19, 2013
    Messages:
    1,689
    Likes Received:
    245
    Trophy Points:
    63
    Location:
    Long Island, NY
    Good info Greg. :)
     
  12. walkersscout

    walkersscout High Wheeler

    Joined:
    Oct 5, 2005
    Messages:
    1,255
    Likes Received:
    153
    Trophy Points:
    63
    Location:
    AZ
    Just leave it disconnected, its not like they were good for much anyway.
     
  13. Dana Strong

    Dana Strong Y-Block King

    Joined:
    Apr 4, 2008
    Messages:
    3,672
    Likes Received:
    509
    Trophy Points:
    113
    Location:
    Sunnyvale, Ca.
    I disagree. It provides useful information, and a voltmeter doesn't take its place because that provides different information. I have both. One does need to understand the systems, just as with Oil Pressure or Temperature gauges.
     
  14. RBS

    RBS Farmall Cub

    Joined:
    Jul 31, 2008
    Messages:
    72
    Likes Received:
    4
    Trophy Points:
    8
    Location:
    Normal, IL
    And at the least you will need to provide a jumper if you don't wire in the ammeter because it is the path from the alternator and most of the truck electrical system back to the battery.

    As Dana stated the ammeter provides very useful information because it clearly shows whether current is flowing in or out of the battery and the relative magnitude of the current.

    Voltmeters are of limited use with modern cars. I am most familiar with the system GM uses that manages alternator output both to increase fuel economy and to extend battery life. With current GM cars you may see a system voltage reading of 15 volts dropping to around 12.6 a few minutes later and it may move rapidly between these states for a long period of time depending upon driving conditions, ambient temperature, state of charge, engine load, etc. As such it really isn't telling you anything useful. The diesel pickups have a more stable voltage reading, probably because at their GVWR they don't fall under the standard EPA and CAFE calculations so there isn't much benefit in micromanaging the alternator. As such the voltage gauge in my pickup is a little more useful and I can tell from reading it when the glow plugs have quite cycling (at cold start they can still be activated for brief periods after the engine is running for emissions control) and when the high current draw intake air heater has turned off. But the voltage readings in my Corvette and Cadillac are of little use.

    Your stock ammeter will already have either a large internal or external shunt so if you are really concerned about the current then decrease the shunt resistance allowing more current to flow through the shunt and less through the meter. The ammeter indicates direction of current flow so even with a very low resistance shunt it will still indicate charge or discharge but the magnitude of movement will be smaller.

    If the electrical demand of the vehicle or the charge capability of the alternator greatly exceed the original then it wouldn't just be the ammeter that is of concern but all of the associated wiring. I suspect your setup is fine as is; if you really feel the ammeter is the weak link then use a bigger shunt. For vehicle fire protection using a good quality harness, good connectors, proper workmanship during install, AND proper use and sizing of fuses are what counts. A lot of vintage vehicle harnesses had fusible links which offer protection by opening under excessive current draw but are a pain but it is important to make sure that if the original vehicle relied upon fusible links then the replacement harness must also have them or fuses. IH was very industrially focused so they likely stayed away from this problematic approach to wire/circuit protection but the service manual would be the final work on that.
     
  15. Scoutboy55

    Scoutboy55 Farmall Cub

    Joined:
    Jan 3, 2005
    Messages:
    156
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Monrovia,CA
    Dana and RBS are on the right track. The alternator only puts out as many amps as necessary. Kind of analogous to the ignition coil; A new 150A alternator will not pump 150 amps through the system unless actually presented with a 150A load. Same with a super duper ignition coil. It may be capable of 50kv, but if only 8kv is needed to span the plug gap, that's all it uses.
    I did a Kwikwire kit in my '79 Scout II and kept the original ammeter in play. Also have an upgraded alternator. No winch, no big-draw lights, just a basic upgraded stock setup. Never had a problem, and don't expect to see any with regards to the stock ammeter.
    The diagnostics of an ammeter are also (to me) more useful than the voltmeter would be, as stated above. Keep your stock rig, it'll be fine.
     
  16. walkersscout

    walkersscout High Wheeler

    Joined:
    Oct 5, 2005
    Messages:
    1,255
    Likes Received:
    153
    Trophy Points:
    63
    Location:
    AZ
    If it had a useful scale, any degree of accuracy, and a voltage gauge, then yes,it would be a useful tool. As they are, I haven't seen one in decades that provided any useful information that was worth the fire hazard they have become. As a rule any alternator that you put on a vehicle now most likely has enough capacity to melt down and amp meter from the 70s or before. Just not worth the risk for the info provided.
     
  17. Dana Strong

    Dana Strong Y-Block King

    Joined:
    Apr 4, 2008
    Messages:
    3,672
    Likes Received:
    509
    Trophy Points:
    113
    Location:
    Sunnyvale, Ca.
    If wiring is old and corroded, replacing it with new wire adequately does the job; it doesn't need to be redesigned for no particular reason. If you started doing that with all the systems on a Scout, it wouldn't be even close to a "Scout" by the time you were finished.

    My 800B came with a 63 amp alternator and, aside from slight modifications of wiring for lights, and the addition of a winch, it still basically stock. It's been used that way for years, is still in good condition, and there's still nothing hazardous about the electrical system. Also, an ammeter doesn't need to have a digital display to be accurate, precise and useful; just needs an operator with some knowledge and experience.
    If you're worried about real hazards, I'd suggest you never get on roads with all the other fools [drivers] and particularly never drive over 55 mph.
     
  18. walkersscout

    walkersscout High Wheeler

    Joined:
    Oct 5, 2005
    Messages:
    1,255
    Likes Received:
    153
    Trophy Points:
    63
    Location:
    AZ
    Thats the truth! Got to watch out for scope creep on IH projects.
    On my bone stock 67 pick up it had a melt down at the amp gauge. On my Scout it was generally difficult to tell anything other than a slightly bigger discharge when you turn somehing on. Granted these are 50 year old gauges. The thing that makes the volt meter more valuable isn't necessarily that it is reading volts, but that the scale has a much greater clarity. You can discern a different of a half volt, whereas on my amp gauges, it is impossible to discern a difference between 5 amps and 15.
     
    Last edited: Jun 14, 2018
  19. Greg R

    Greg R Dreams of Cub Cadets

    Joined:
    Mar 23, 2002
    Messages:
    4,178
    Likes Received:
    272
    Trophy Points:
    83
    Location:
    Lebanon, OR
    I just need C , D, or the middle. C is good, D is not good. Middle is just right.
     
  20. RBS

    RBS Farmall Cub

    Joined:
    Jul 31, 2008
    Messages:
    72
    Likes Received:
    4
    Trophy Points:
    8
    Location:
    Normal, IL
    You can test/scale/calculate a different shunt for your ammeter just using your battery and some old headlights or another DC operated load with a known current draw. For a simple pretty accurate test load use 250 feet of standard 2-12 electrical wire and tie load and neutral (black and white) together at one end and the other end will provide you with a resistance of 0.794 ohm which will draw just under 16 amps at 12.6 volts.

    Of course for this test you want the ammeter removed from (or at least from the wiring) of the vehicle.
     

Share This Page