Question about battery Drain

[MokiCruiser]

I have an 18 ft boat that I have been restoring ......... it was such a wreck I should say rebuilding! Anyway, the older I get the bigger coward I become when it comes to being on the water without redundancy in everything, so I've installed a 1975 70 HP Johnson and a 1997 15 HP Evinrude for a kicker. At the back of the boat I have a dual marine battery setup with a typical switch, off, battery one, battery 2, and both. Both are smaller group 24 Interstate Marine batteries with 405 CCA and 505 CCA.

I newly installed a tachometer, a volt meter, dual horns, a Ray-marine GPS/fish-finder combo, a marine band radio and repaired and hooked up the existing bow and stern lights. I have a another marine deep cycle group 27 battery with 675 CCA and 840 CA at the front of the boat. If I run the GPS/Fish finder full time, leave the marine radio on but rarely gab on it, rarely honk my horn at anyone, maybe leave on the small stern and bow lights, will that battery keep everything running all day without running itself down since it will be isolated from the charging circuit? And while I'm asking, how would I hook up to volt meter to show the volts on the battery that's charging or both?

 

[Scott Danforth]

Volt meter runs off the ignition which displays voltage from the alternator and which ever battery the main switch is on.

 

[MokiCruiser]

Well there is no alternator since it's an outboard, and how exactly would I hook that up? Hot lead to on and ground to ground, and both on the ignition? And the light in the voltmeter is a separate wire ....... what would I attach that to?

 

[spoilsofwar]

Usually gauge lights are part of the nav lights circuit; you switch the nav lights on, and logic reasons you need the gauges to illuminate. Not the anchor light circuit, cause you don't need gauges illuminated at anchor...

As for the first question; maybe?.
To answer with any degree of certainty we would need to know the amp draw of all the items wired to that isolated battery, and for how long they will be drawing. Also need to know the reserve capacity. You're just asking us to guess, really. So if you want my guess, I would say, it's probably ok for an average day of fishing... But I don't know if that will make you feel any better when you're out on the water and it goes dead.

 

[MokiCruiser]

About the gauge lights and nav lights, that makes sense ............... as far as the amp draw on the Ray-Marine A70, can't find the amps but I see that it uses 8 to 10 watts of power. The Marine radio is a standard and it uses about 1/3 amp to receive and 6 amps to transmit. The bow and stern lights are just those little 12 volt bulbs you would use for turn signals, and the horn .............. well I have no clue but assume it would draw no amps unless I honk at somebody. As far as the reserve capacity, can't find that either but it looks like ko==most of these same size group and rated deep cycle almost all have 180 at 25 amps.