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Related

Mini-Trail 70 Converter

djdan
djdan over 7 years ago

Hi! all

I have bought a Honda trail 70 that have no lights (All burned) so I would like to add LED on 12Vdc.

The thing is , the AC from the generator is 9 to 34VAC on one side and 11 to 42Vac on the other.

9Vac is idle and 34Vac is almost high RPM. I tried LM7812 that work quit good (Very hot on heat-sink)

for lower then .400A but I can't go higher than 30, the IC cut to protect himself. I tried a Buck converter

LM2596 but became very hot without being able to put some Heat-sink on it. I put a diode to cut in half

the pulse from AC, plus a 1000uf for filtering. I try some resistor (2-4-6 ohm) between the AC and the

diode but I loose the lower volt, so the head light doesn't work properly.

 

My question is: What can I build to have a regulator that can accept the 9 to 34Vac and keep the

12Vdc as output at 2A for the headlight , or if possible 3A (to include the brake and park lights)

(I know that at low input volt, the output will be lower than 12) but at least there will be some. 

And I like too, to be able to build another one that can go down to 6Vdc cause the lights inside

the speed-o-meter are still 6v. No LED as small enough (For now) to fit inside. No more battery

inside the bike (No use anyway).

 

Many thanks to anyone that can help. I'd like to build it and learn by the same time.

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  • mcb1
    mcb1 over 7 years ago in reply to ntewinkel +2 suggested
    I find it strange that it would be AC rather than DC The coil will be AC output, and then usually a single diode rectifier (some bikes a full wave rectifier) somewhere. The battery will hold down the charging…
  • Fred27
    Fred27 over 7 years ago +1 suggested
    So the 12V lead acid battery is damaged? This may be the problem. The charging circuit is expecting to be charging this battery and without it you will get the significant variation in voltage that you…
  • Fred27
    Fred27 over 7 years ago +1
    Oh - it's a 6V system. I haven't seen one of those for a couple of decades! They never work well even from new.
Parents
  • Fred27
    0 Fred27 over 7 years ago

    So the 12V lead acid battery is damaged? This may be the problem. The charging circuit is expecting to be charging this battery and without it you will get the significant variation in voltage that you're experiencing. Replacing the battery will be the best way to solve your issues.

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  • djdan
    0 djdan over 7 years ago in reply to Fred27

    Thanks for the reply. The charging circuit is on the higher output 11 to 42Vac.

    So It is not in the way for the lighting.

    There is two coils on this bike.

    One for charging + stop lights + directions lights.

    One for Headlight + Speed-o-meter lights.

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  • ntewinkel
    0 ntewinkel over 7 years ago in reply to djdan

    >the AC from the generator is 9 to 34VAC on one side and 11 to 42Vac on the other.

     

    I find it strange that it would be AC rather than DC, especially for charging the battery. Could there be a problem with the generator/alternator's voltage regulator (or do ATVs have those?)

     

    Cheers,

    -Nico

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  • mcb1
    0 mcb1 over 7 years ago in reply to ntewinkel
    I find it strange that it would be AC rather than DC

    The coil will be AC output, and then usually a single diode rectifier  (some bikes a full wave rectifier) somewhere.

     

     

     

    The battery will hold down the charging, and with the lights ON it usually drops to something acceptable.

    It's not uncommon for the voltage to vary quite a bit on these 'simple' bikes and you'll see the headlight brightness drop a lot at idle.

     

    Image result for honda 70 wiring diagram

    copied from https://sep.yimg.com/ca/I/dratv_2269_316662841

     

    I suspect the red wire from the rectifier joins where it crosses the other red wire from the battery plug.

     

     

    The old car generator regulator simply interrupted the output to the battery when the voltage got too high.

    Because these don't have high powered generators they don't bother with a regulator.

     

    Mark

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  • mcb1
    0 mcb1 over 7 years ago in reply to ntewinkel
    I find it strange that it would be AC rather than DC

    The coil will be AC output, and then usually a single diode rectifier  (some bikes a full wave rectifier) somewhere.

     

     

     

    The battery will hold down the charging, and with the lights ON it usually drops to something acceptable.

    It's not uncommon for the voltage to vary quite a bit on these 'simple' bikes and you'll see the headlight brightness drop a lot at idle.

     

    Image result for honda 70 wiring diagram

    copied from https://sep.yimg.com/ca/I/dratv_2269_316662841

     

    I suspect the red wire from the rectifier joins where it crosses the other red wire from the battery plug.

     

     

    The old car generator regulator simply interrupted the output to the battery when the voltage got too high.

    Because these don't have high powered generators they don't bother with a regulator.

     

    Mark

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