To determine if a battery is being discharged, first the battery must be checked to determine battery condition. A battery is fully charged when the voltage is measured with a digital volt meter and the voltage is 12.6 or 12.7 volts. If a battery is 12.0 volts the battery is 75% discharged.
An easy way to determine what 12volt circuit is using power is to remove all fuses from their holders. Before removing fuses, note their position as to amps. Indivually replace one fuse at a time and note any sparking as fuse is installed. Nope the 12 volts will not shock or harm any human. If no sparks are noticed. check battery and disconnect the ground cable untill some 12-15 hours have passed. Then again check battery voltage. If possible make all the checks with the 120 volt ac not connected. NO shore power. Depending on results of tests, more checking maybe required.
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