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H4 LED drop in compatibility w PMA/Pamco/regulators etc.

Discussion in 'The Garage' started by Torchard, Oct 14, 2021.

  1. Torchard

    Torchard XS650 Enthusiast

    So, I see the posts on this subject range over many years, and as pointed out the tech continues to evolve. I wasn’t able to fully understand/find explanation for the pros and cons so will try here: I am considering an H4 LED into a 6” after-market headshell. My hope is this would place a lower demand when idling/start-up given that I’m using a capacitor. The low beam is wired direct and while contemplating an on/off switch, I wondered if an LED bulb is a worthy alternative to the switch? Is the load less than conventional bulb? And I read references that these are not PMA/regulator friendly. I have PMA and regulator and ignition from one of the popular providers. If compatible, are they plug and play as this one suggests?

    https://auxito.com/products/9003-h4...bDxBFdAI-88kLEilbtsKJPA8omCKl0kgaAsAMEALw_wcB
     
  2. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    With the PMA, you need to use as much available current as you can. Therefore, an LED light is not the best option. With your capacitor and no battery, the halogen light coming on straight away is no good. You need a switch for the lights, so you can leave them off until running. PMA output is max at all times and there is no control. That current has to go someplace. It's best if the lights use as much as possible.
     
    grizld1 and Torchard like this.
  3. bosco659

    bosco659 XS650 Junkie Top Contributor

    I’m running an led headlight with a PMA and didn’t realize this was not a good thing. May need to switch back to halogen??
     
  4. Torchard

    Torchard XS650 Enthusiast

    Is your headlight on at start up?
     
  5. Torchard

    Torchard XS650 Enthusiast

    Battery or capacitor?
     
  6. bosco659

    bosco659 XS650 Junkie Top Contributor

    Headlight switched at handlebar. Normally start with it off but could start once in a while with it on. Running with a battery.
     
  7. wannabridin

    wannabridin XS650 Guru

    Isn't a battery just fine w/ one since there's enough reserve capacity?
     
  8. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    The PMA will make whatever current it makes. What you don't use gets shed as heat. Do you have a voltage regulator with big cooling fins exposed to the wind? That heat is the issue.
    The stock alternator produces current according to the demand. It does it by changing the strength of the magnetic field in the rotor. The PMA has permanent magnets. I know that may be an oversimplification.
     
    JAX71224, Jim and Torchard like this.
  9. bosco659

    bosco659 XS650 Junkie Top Contributor

    Yes I have a large VRR and has plenty of air for cooling. I guess I’m ok then. Thx.
     
    jetmechmarty likes this.
  10. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    You may well be just fine, especially equipped with new understanding. @Torchard may be fine with it too, but if he hasn't already gone there, I think there's a better way.
     
    Torchard likes this.
  11. Torchard

    Torchard XS650 Enthusiast

    I’ll await those who know, but I suspect the battery will buffer the PMA/regulator
    I’m keen to hear you better way suggestion?

    FYI I think for the near term I’m going w the switch and keep the halogen. This bike has yet to be properly tuned - could be some timing and jetting adjustments that impact start up too. There are other options too: a conventional battery, one of those wee batteries, a lesser wattage halogen, others? Many thanks for the input as I have a better grasp on key issues to consider.
     
  12. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    I believe that's the right thing to do.
     
  13. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    If you don't already have one, an onboard voltmeter is essential for a PMA setup in my opinion. As Marty already pointed out, a PMA regulator is always working its butt off shunting excess current to ground. That generates lots of heat. Heat kills regulators at a far higher rate than the stock setup. A voltmeter would (hopefully) give you enough advance warning to prevent getting stranded or worse... cooking a battery.
     
    jetmechmarty and Adamc like this.
  14. Torchard

    Torchard XS650 Enthusiast

    Hmm. Makes sense. And the voltmeter sits after the regulator? And if you’re seeing a high voltage output of X you start thinking of ways to shunt excess output?

    like maybe a huge subwoofer?
     
    Jim likes this.
  15. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    You might have the right idea, but no. It means your voltage regulator went Tango Uniform.
    upload_2021-10-15_12-58-45.png
     
    Torchard and Jim like this.
  16. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Voltmeter reads battery voltage. Tie it to the power out line from the ignition switch.
    With a correctly operating system, it will give you a baseline of what you should expect to see. After that you just look for unexpected changes in voltage.
    Do a forum search in the garage. There's lots of how-to's on installing one.
     
    Torchard and jetmechmarty like this.
  17. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    PMA Reg/Rectifiers have 2 types. Shunt and series.

    Shunt reg/rect

    The regulator part controls the amount of power going to the battery. If the PMA is a 200 watt and the bike is using 130 watts then 70 watts is being made but not going anywhere. This gets converted to heat and the cooling fins bleed this off. If the fins cant get rid of the excess heat/power fast enough the Reg/Rect unit lets any excess heat back into the line to the PMA and over heats the Stater.............. So the stater is making power to feed the reg/rect ,(but that is feeding any excess power converted to heat), it cant shunt off, back in to the stater causing it to burn out.

    if you put LED lights all through the bike with a PMA then the bike will be using less Wattage. That means a bike that is usually using 130 watts could be saving 20-30 watts so now it is only using 100-110watts of the 200watts. So a 200 watt PMA Reg/rect instead of bleeding off 70 watts now has to convert 90-100 watts to heat, making it more likely to cause the reg/rect to overheat and burn out the stater


    Series Reg/Rect.

    The series Reg part of the Reg/rect controls the amount of power to the battery. The PMA still puts out 200 watts and if 130watt's is being used then 70 watts is the excess..........On the series Reg/Rect the regulator controls the amount of power to the battery, so it doesn't get to much, (same as the shunt Regulator).

    The PMA still puts out 200 watts continuously. The difference is the series regulator shuts down one of the 3 phases (coming from the stater, white/yellow wire), for a short period of time. It then swaps over to another 2 of the 3 wires and receives power from those 2 for a short time. It keeps swapping wires so only 2 phases are being used at a time and drops the feed from one phase. This means there is less excess power the Reg has to convert to heat so the cooling fins have less to bleed off and stops any excess being feed back to the stater so the stater doesn't burn out.

    If by any chance the battery is failing and the bike need more power to run the series reg will go back to using the 3 wires, (3 phases), to feed the power into battery to feed the bike.
     
    Adamc and Signal like this.
  18. Torchard

    Torchard XS650 Enthusiast

    Roughed in a switch. Started on second kick. Brum. Brum. I wish I figured this out three weeks ago. Ha. I’ll finish that wee project and move onto the next head scratcher. Thanks all.
     
    jetmechmarty likes this.
  19. Torchard

    Torchard XS650 Enthusiast

    Super helpful, thanks, by explaining the processes underway. Helps to visualize what happening under a given set of conditions.

    Maybe the excess energy could heat a seat pad ;).
     
  20. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    Exactly. if your in a colder climate heated grips/vest/seat will work to help a shunt regulator...............But when the warmer weather comes those things aren't being used.
     
    jetmechmarty likes this.

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