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Idle volts

Discussion in 'Amplifiers' started by Ziploc, Feb 13, 2021.

  1. Ziploc

    Ziploc Well-Known Member

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    Guys , I have a 110 alt and when I’m ideling my truck with heater on lights radio basically the works on and cb and 2 pill 1446 I’m assuming it’s pretty normal to see the battery gauge drop some while modulating and after unkey it recovers quickly. With a 110 amp alt wonder how much of the 110 amps I’m using at idle ? Thoughts


     

  2. Beetle

    Beetle Sr. Member

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    Put a DC ammeter in series with the main power lead to the amplifier and find out. OR get a DC clamp-on ammeter and use that. Handy instruments to have if you're mobiling.
     
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  3. 999

    999 Well-Known Member

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    I'd bet at idle it's between 60 and 75 amps. An alternator doesn't usually reach peak output until the engine is above 2000 RPM.
     
  4. Ziploc

    Ziploc Well-Known Member

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    So that’s your guess while modulating? So everything sounds normal to you ?
     
  5. cralt

    cralt Well-Known Member

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    Usally the bigger the alt the less efficient it is at idle. If everything else is up to snuff then maybe you could take a page from the hotrod guys playbook and start playing with underdrive/overdrive pulleys...

    Who made the alternator? Did they give you a dyno sheet with it?
     
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  6. Ziploc

    Ziploc Well-Known Member

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    It’s just a lil 2 pill 1446
     
  7. cralt

    cralt Well-Known Member

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    Well like 999 said that 110 alt isn't 110 until higher RPM. It may be a lot less at idle and with the heat and everything else it may be right at the limit. If you kick the idle up a few hundred RPM and the problem goes away then you might be able to swap on a smaller pulley to shift that number down. Aeromotive and Powermaster make them for common types. But this again is after you rule out bad connections, cables, batttery etc etc.

    Screen Shot 2021-02-13 at 5.49.32 PM.png

    Anther option is to just upgrade the battery to something with better reserve capacity to carry you through the keydowns.
     
  8. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    There are several ways to look at this...

    If you are using say, a Chevy Nova with a 350 V8 small block, the built in regulator and regulation system is different from the more integrated charging systems of their successors like that found in a Equinox.

    - so the way the system works and to provide you a solution is not as simple as
    • - just open the hood and tweak the idle speed screw from 750 RPM to 825 RPM
    • or - got a screwdriver? locate the "Idle Up" solenoid and follow the wire back to the ECM
      • - there is a purple wire with a Red stripe that you "tap into" as this wire tells the ECM to engage the Idle up and you won't have too many low-battery problems anymore...
    It's a little more complex.

    The newer vehicle electrical systems take more care of their battery and regulation of their system, it's ECM and emission systems senses load on either Electrical or Engine load by sensing speed and voltage drops caused by loading. So if you're having issues with the battery getting sucked dry, then you need to review how you are hooking up the amp system - if' its' Directly to the battery or it's Buss, (cables) then you need to review it's quality - for most of the time the loading caused by electrical will force the engine to increase it's idle speed to offset the voltage drop automatically.

    AC systems and Climate control systems that use the engine do this thru the wiring harness as the clutch kicks in and the engine revs to to offset the load.

    Most power steering systems are now electric-driven. Same concept but instead of using the wiring harness for the Idle up signal, they simply siphon off power from the electrical system.

    In these systems, as you drive the battery and electrical system supplies the power to drive that motor and pump system. When the regulator on the vehicle senses voltage drops, this signal tells the ECM that an electrical load is being placed on the system and adds more power thru the ECM to sustain the load.

    When the load gets too large, this can set a condition code thru the DTC - because of its' own self-check of the systems it uses. So since idle speed and load affect emissions - this affects the vehicles ability to run let alone beat the emission tests - you might want to review what you did to get the amp hooked up and run it while you idle.

    Right now, if it has not set a light on the dash, then the amp isn't telling the vehicle I need more energy - so it leaves that choice up to you. The load isn't severe enough to set the DTC code so the problem then falls onto you and how long you need to idle the vehicle.

    Most newer vehicles are programmed (Read:Smartly Enabled) to recognize issues with the electrical are not to be taken lightly and monitor battery condition. Doesn't mean all vehicles are done this way, many are still basic load - voltage drop - idle up and continue - if the battery dies - you walk to the store and get another.

    But the batteries health and charging system, and all your accessories, not theirs - you connected to it, is still your responsibility. Warranty Optional...
     
    #8 Handy Andy, Feb 13, 2021
    Last edited: Feb 13, 2021
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  9. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Put your foot on the gas and idle it up a bit and see if it helps. With the boom system in my big truck, I put it in neutral at stop lights. Yeah, I'm that guy.
     
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  10. Slowmover

    Slowmover Elmer

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    MECHMAN and others sell custom alternators.
    See also CE AUTO SUPPLY.

    Peak amperage will be above idle when in Park, but how much higher in rpm is due to a number of physical factors not just engine controls or accessory draw.

    Utilizing a dedicated automotive starting battery is par for the Amateur Radio course.

    See k0bg on the subject.

    .
     
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  11. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    upload_2021-2-13_19-11-39.png
    If the above is your current (SIC) thinking of what Alternators are...
    You have a lot of catching up to do...

    upload_2021-2-13_19-14-46.png
    Even more Current thinking is the Regulation system is no longer left to "sense" the Output Terminal
    on the newer alternators - they place it back to the ECM / BCM / PCM systems to regulate their needs directly on the output of the Alternator to affect all the systems and sub-systems.​


    If you have a CAM based system, the regulation is extremely important for it's own needs - even though it operates at a different voltage and communication level. By that alone the purity of the feeds needs to allow the system to intercommunicate - SRS TRAC, ABS just to name a few - all rely on a interconnected mess of wires and they use sensors - if the voltage is not smooth- they will trigger events you don't want to have happen to you.

     
    #11 Handy Andy, Feb 14, 2021
    Last edited: Feb 14, 2021
  12. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    When you ask such a question...

    Most alternators use a Diode Trio - two of them, one for the Rotor / Stator regulation circuit, another for the Stators output direct to the output terminal - which is a heavy amp unit and can fail in a myriad of ways.

    It is obvious that when you watch the lights dim and hear the blower motor noise drop every time you key up - it should tell you that; at that speed of Idle; the alternator pulley - is not making enough field strength at the ROTOR to get picked up by the STATOR - this gets into a grey area for as some already suggested, you can change the pulley to a smaller size, which doesn't change the pulley belt or the size of the harmonic balancer and pulley - you're changing - shrinking, the size of the Rotor's pulley - so the belt will make the Rotor spin faster - and may bring up the Rotor field to a speed that the stator can see more capture in it's windings to make the diodes see a higher frequency.

    Putting on a bigger alternator - you have several ways they do this, more windings in the Stator, Rotor or both and offer a larger Diode Trio to handle the output and even change the charger regulation system to be more sensitive to regulation voltage drops. In any of these cases - you suffer the torque and power losses and dangers associated with them.

    What could be the Danger?

    I mentioned Harmonic Balancer pulley system - it is 1/2 the means the engine uses to smooth out power delivery and also reduce vibration that can cause a resonance that will cause long term damage to the motor.

    If you change the Alternator Pulley, that's fine, but remember the torque it will place on the belt and if you don't run stuff that needs 60-70 amps that requires you to run such a system all the time the motor runs, you should be just fine.

    It's when you have A/C Power steering and that Alternator on the older style balancers - that can shear off a dog clutch and you're left stranded looking for a new motor.

    But what you have not told us, is what you've done to the Electrical system to offset this loss you have now...

    Have you...
    • Upgraded the Output wire to a higher AWG gauge to send more power into the system with less voltage drop?
    • Solder the lugs used on this cable to further reduce the losses and improve the reliability of the system?
    • Have you checked, cleaned, repaired, tightened mounting bolts, even soldered the Lugs of the Battery Ground Cable?
    • Cleaned - upgraded the Battery and or it's terminals?
    Just some things to think about before you get left stranded - so you're not left wondering why it happened.
     
    #12 Handy Andy, Feb 14, 2021
    Last edited: Feb 14, 2021
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