QUICK CHARGE

DUAL 3.0 USB CHARGER VOLTMETER

$13; amazon.com

One dual USB port charger device fits the hole size of a cigarette-lighter port. It reads out battery voltage while charging two USB devices at 3 amps each. A water-resistant cap fits over the charge ports when not in use, and a small display window allows voltage readings to show through.

IN THE BOX: It comes with a charger/voltmeter plug with a locking ring and attached waterresistant cap. Red and black wiring comes with a fuse holder and fuse.

INSTALLATION: Installing it couldn’t be easier. We crimped terminal rings on the cable ends and hooked them to power (red) and ground (black) wires. The mounting hole is easily drilled, and a locking collar holds it in place.

WHAT WE SAW: This simple gauge could be connected in companion with a 12-volt power receptacle or in place of one. The voltage readout in a blue LED was legible in daylight or in the dark. USB charge ports are separated by the battery voltage readout, making them easier to pull or insert.

OUR TAKE: In more-involved battery systems, those powering multiple engines and a vast array of navigation electronics and house devices, simply monitoring voltage is insufficient for safe operation out of port. But for a runabout with one or two batteries and an audio system to power, voltage monitoring is adequate if you make sure to charge the starting battery before it dips below 12 volts.