Battery switches and shore power
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What the battery switch positions do, protecting the alternator, safe shore-power plug-in order, the reverse-polarity light, and electric-shock-drowning risk.
Sources (7)
- 1/2/Both/Off switch: position selects which bank supplies loads and receives alternator charge; Both parallels the banks; Off isolates both — marinehowto.com
- Passing the switch through Off with the engine running creates a load-dump voltage spike that can destroy alternator rectifier diodes and damage DC electronics; dedicated start battery vs house bank — marinehowto.com
- A fully charged 12 V lead-acid battery rests around 12.6 V — batteryuniversity.com
- Turn off both dock and boat breakers before plugging or unplugging; plug the boat inlet first, then the pedestal; reverse to disconnect (dock end first); inspect ends for discoloration, melting, cracked insulation; avoid household extension cords; never swim in marinas — fisheriessupply.com
- If the reverse polarity light turns on, disconnect, do not use the power and tell someone at the dock — pysystems.com
- Electric shock drowning: low-level AC current in the water causes muscle paralysis; most deaths occur in marinas and docks with current from dock wiring or boats on shore power — electricshockdrowning.org
- Shore power: pedestal breaker off before plugging in, connect, then turn the pedestal breaker on — marinemax.com
General guidance for recreational boaters — your engine and equipment manuals and local regulations come first.