# scooter voltage regulator schematic



## 1fixitman (Nov 24, 2009)

The intent of this thread is to design a proper work around for a voltage regulator/rectifier circuit for a chinese scooter between 50 cc and 150 cc. The current design that can be purchased for about $26 goes out and blows about $36 worth of bulbs. I believe the load on the ac portion of the regulator is 125 watts.
4 pins on the regulator.
White wire ac voltage 15-80 volts variable voltage and frequency rectifies thru a half wave bridge rectifier and keeps voltage below 14.5 volts DC for charging the scooter I believe by shorting the extra voltage to ground. It also keeps the current flow at or near 0.5 amps so as not to overcharge the battery(4-10 amp hour batteries wet cell lead acid or AGM)

Green is ground

Yellow is to run all the lights on the scooter. AC voltage between 15-80 volts and variable frequency. On this portion voltage is knocked down to 12 volts AC by grounding the extra voltage to ground and supplying AC voltage to the 125 watt cumulative load.
Any help with design and heat load removal would be great. I can solder and read prints if they are a good document.
Thank you for reading,
Dwayne
Augusta, GA


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## JohnWill (Oct 19, 2002)

I'm surprised they use A/C to the lighting circuits if they're also trying to power them from the battery! This would be a most unusual electrical system...


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## 1fixitman (Nov 24, 2009)

The way this system works is that one AC wire feeds in and is regulated to not exceed 12 volts AC. This circuit powers up most of the lights required while running. The excess voltage is shorted to ground.

Another wire with a completely different AC signal is fed in to the circuit for charging the battery. That ac signal is rectified thru a half wave bridge rectifier and any extra voltage is shorted to ground so the end result is 14.5 volts DC at about 1/2 amp for charging the battery.

The loads that come off of the battery are only used for short periods of time like the blinkers, brake light, horn and the starter for starting the engine.

The AC loads are 4 headlights( two at 5 watts each and two at up to 35 watts each), one 5 watt dash light for the speedometer, one 5 watt dash light to illuminate the fuel gauge, one 5 watt lamp for illuminating the license plate, the running light portion of the tail lamp at 5 watts (the lamps are dual filament), two running lamps on the front at 5 watts each. These lamps only need to operate when the bike runs so it is on an AC circuit for long term use so as not to drain a battery over time. All of these ac loads are about 125 watts which would be about 10 amps total on a similar DC system and would drain a 9 amp hour battery in about an hour.....remember from the above DC circuit that it only charges at 1/2 of an amp so it does not damage the battery from over charging. Hope this helps clear things up.
Dwayne


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## JohnWill (Oct 19, 2002)

Well, the mystery here is the "shorted to ground", because clearly that's not really happening.  That would put a huge load on the generator for no reason.

In this position, I'd probably be looking at a triac regulation circuit for the A/C and a simple DC regulator for the D/C. If the A/C really goes up to 80 volts, you'll probably have to consider a switching regulator that can handle the wide voltage swings.


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