The 'regulator' is twofold - it has a rectifier section that changes AC into DC to charge the battery and the regulator section to limit the DC voltage to 14.8 volts to prevent overcharging the battery. The stator produces the AC voltage (upwards of 60 volts) - when the rectifier changes the AC to DC, it cuts the voltage approximately in half, then the regulator limits it. If the conventional battery was low on water, it usually indicates one of two things; either the battery has been overcharged and some of the water has been evaporated out of the acid or the battery is damaged and the plates have absorbed the liquid. A discharged battery will be low on liquid until the battery is charged. Charging drives the liquid out of the antimony on the plates and replaces it with gas. Batteries operate on gas - the liquid is just a medium that promotes the movement of the gas from one plate to another. The gas moves one way during discharge and the opposite way during charging. The natural movement is to discharge. That's why to charge; the voltage has to be higher than the battery voltage to force the flow against the natural direction of movement.
Check the output voltage with a meter across the battery terminals - the voltage should not exceed 14.8 volts. Typically when the battery reaches 14.8 volts, the regulator will cut the voltage - when the battery discharges to approximately 13.2 volts, the regulator will turn off and the voltage will increase to 14.8 and then cut off again.
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