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Thread: Charing voltage drops

  1. #1
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    Charing voltage drops

    Apologies for the Engrish in the thread title.

    I think I might have some charging voltage issues. Bikes is an Aprilia Falco with an eastern beaver wiring kit connecting the FH008 Mosfet directly to the battery. Charing voltage is a nice 14.3v or so at the battery when lights and all the other stuff is off. With low beam it drops to 13.9. High beam gives me another .5v drop. Same thing with rear brake lights or fans. Even see a drop with indicators on. This is irrespective of RPM (checked at idle to 4000 rpm or so). When ancillaries it just doesn't get to 14V anymore. Also the dashboard light and parking bulb briefly flicker when the brake lightis activated.

    I checked the alternator resistance at the white barrel connector and the connector at the regulator. Resistance at every terminal is withing spec (below 1ohm) and there is no visibile damage to the terminals or connectors or what so ever. They look perfectly fine with no loose wiring. Charging voltage is above 60acv at 4000 rpm. I don't have any blown fuses or anything like that. Bike just had a new Yuasa YTX14BS battery and it fires up perfectly with no hesitation.

    Before these issues started with the current wiring/FH008 regulator setup always gave me around 14.5v no matter what was on or not. So it has worked properly with the Mosfet regulator before this problem started. I am thinking the regulator might be going south, but I haven't seen a lot of Mosfet FH008 failures.
    Last edited by Yzf600r; 09-15-2015 at 11:54 PM.

  2. #2
    apriliaforum expert Gabro's Avatar
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    can you try install back the stock regulator and see what happen?!
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  3. #3
    apriliaforum expert
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    Check your earths first, Check for loose conection, dirt build up etc
    I'd rather have a full bottle in front of me than a full frontal lobotomy

  4. #4
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    ground on the engine is pristine and no loose bolt (there is no frame ground on the Falco).

    Good one on the old regulator. I have it lying around somewhere though I will have to crimp some Metri Pack connectors to be able to try it out.

  5. #5
    apriliaforum expert flossy's Avatar
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    except for the dash and parker light flicker, you will always get a voltage drop with any other light on, starts strong, unless you get resets etc why worry just hook in,

  6. #6
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    Problem is I go to 13 with high beam and brake lights, which is too low. The setup used to give me a clean 14v+.

  7. #7
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    It even got worse with the old regulator hooked.

    Then I replaced a tatty looking headlight loom and replaced a 30a fuse that sits between the battery and the regulator. The weatherpack fuseblock that holds the fuse isn't attached to anything and is just bouncing/vibing around, which the fuse doesn't seem to like. The voltage now longer drops when the brake light is activated and with high beam on I get 13.9V. Problem seems to be solved, though the dash sometimes gives dangerously low voltages. I might install a battery bug or volt meter thingee for peace of mind.

  8. #8
    apriliaforum Junkie Ario's Avatar
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    my Tuoldo is also very fragile to lights ON/OFF. When I push the brake the voltage on the dash drops at least by 1 - 1.5 [V] is this a sign that the regulator is faulty?

  9. #9
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    I bought these http://www.apriliaforum.com/forums/s...ight-led-bulbs --- no more big voltage drops when applying the brakes.

  10. #10
    apriliaforum Junkie Ario's Avatar
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    Quote Originally Posted by Yzf600r View Post
    I bought these http://www.apriliaforum.com/forums/s...ight-led-bulbs --- no more big voltage drops when applying the brakes.
    I will order them from here http://www.aliexpress.com/item/2pcs-...292731089.html

  11. #11
    apriliaforum expert J.R. Bob Dobbs's Avatar
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    I installed a different (much more expensive!) set, from af1. They are very bright, and the voltage on the dash no longer drops when brakes are applied.

    When it did drop on the dash with the incandescent bulbs, it did NOT drop at the battery, so the dash and the brake lights must be getting voltage downstream of some resistance. Might be enough to stop dash resets?!? Haven't had a reset since installing lithium battery anyway (fingers crossed)

  12. #12
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    hey mate.. sounds like your bike suffer the same problemo with mine gen2 rsvr...

    on idle it will charging strongly.. but nope when headlight is turn on..

    have you check your stator coil? as mine is already fooked on 1 of the pin wire...

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