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K & C Stork Solar Power Consultants

Charging Regulators PDF Print E-mail

Over charging batteries may cause excessive water loss, swollen plates, and loss of active material. The active material may also build up at the bottom of the battery forming sludge and could cause a short circuit across the bottom of the plates.

To prevent overcharging of a battery, a charge regulator is used to sense when the batteries are fully charged and to stop or decrease the amount of current flowing from the solar panels to the battery The maximum that a battery should be charged to is around 2.5 volts per cell (or 15 volts for a 12 volt battery). There are exceptions to this rule, however the average person should follow this as a guide. battery warranty may be void if overcharged.

Regulators can be designed to switch off parts or all of a solar array in stages. Another type of regulator (commonly known as PWM or Pulse Width Modulation) may continuously adjust the charge supplied to the battery to supply the optimum charge voltage/current at all times.

There are a wide variety of regulators available, however most can be classified as one of two types: series or shunt.

Shunt Regulators
Shunt regulators dump excess power as heat or divert it to a dummy load. This excess power may be used to heat water or operate other systems. When shunt regulators are used, the energy sources are operated at full load at all times. These are commonly used with wind turbines and micro-hydro applications.

Series Regulators
Series regulators are the most Common and operate like a switch disconnecting the charging source from the battery when not required. These regulators may be configured to switch the power supply to an alternative load such as water pumping or an auxiliary battery bank (altered/programmed to become shunt-like in their operation, but are not true shunt regulators because the alternate load may vary in demand). Series regulators are also available with PWM (pulse width modulation) control. PWM is the preferred option, as this can taper the charge avaliable down to that required by the batteries and/or load. PWM can also be used to control the dumping of excess energy being produced by wind and hydro turbines, to ensure a constant load is applied at all times for maximum efficiency and life expectancy.