I switched mine to the accy. Actually, I basically spliced it into the radio power. No complaints yet. Power consumption should be nill. Besides, when I float, I do like to check depth periodically.... we don't always anchor.
The 12V plug is simple. I got one of those three-way splitters like for a car, cut the end off, and wired it to one of the unused fused circuits on the power panel. It's mounted just below the dash on the driver's side (next to the 400W inverter I installed). This splitter has a switch on it already, and wiring down stream a fuse helps.
good luck!
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Walt B
"Debt-Charged"Black '07 H210SS6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.