Boat Battery Monitor and Alarm

The Low Battery Alarm from Battery Failsafe Devices monitors volts and alerts you when your battery gets too low.

Knowing the voltage of all your boat batteries at any given time is critical to managing your onboard electrical power system. The Low Battery Alarm from Battery Failsafe Devices ( not only tells you the voltage, but also alerts you if volts fall below a pre-set minimum.

The company sent me one, and I mounted 3x4-inch instrument in the cabin, with an on-off-on toggle switch so I can monitor both the starting and house batteries. The LED display is easy to read, and setting the minimum thresholds for the alarm is about as simple as it gets. I tested it by setting the minimum relatively high, and sure enough, it emited a piercing audible alarm and flashed a red light to indicate a low battery.

The device can be used for either 12- or 24-volt systems. I chose the cabin location to install it because the instrument and its plug receptacle are not waterproof, and the flashing green “good-to-go” light can be a bit blinding at night, if mounted at the helm. The Low Battery Alarm can utilize a cigarette-lighter style plug or you can hard wire it to the battery, as I did. It sells for $57.95, plus shipping, and that includes a one-year warranty.

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