On a recent run from Charleston, S.C., to the Chesapeake Bay, a low-voltage alert flashed on the multifunction display. The 12-volt power supply was slowly dropping. The crew went to the tender, stripped its battery and charger, and used them to replace the failing battery as a temporary solution, but the smaller charger could not keep up with the big boat’s demand. As night approached, voltage slowly dropped until the system crashed.
This failure took out the chartplotters, depth, speed, radar, AIS and VHF radio, leaving the crew flying blind.
Here’s what happened, how they handled troubleshooting, and how they repaired the system to add redundancies for the future.
HIGH VOLTAGE
There are many excellent reasons for utilizing higher voltages in a DC system. With 24 volts rather than 12 volts, smaller wiring can be used, and electrical efficiency increases. Lighter-gauge wire also reduces weight, sometimes significantly on a
