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Dual Battery Switch Installation

lakebum said:
Jim, I was serious when I said we need to beat this some more. I always like to get differing opinions and appreciate your views. Had not considered the power-on wire for the amps. One thing I found that I thought was odd on my boat is it has two #10 wires with 30 amp fuses leaving the batteries but are tied together at the helm. Works but thought it was odd but makes sense. Steve
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So you get power to the dash with whichever battery is connected or switched on. It doesn't seem they would be "isolated" though.
 
The fuse is typically located at the source of power, and protects the attached wire (and equipment downstream). To me it sounds like a typical dual amp setup - each 30amp fuse is protecting a wire run an individual amp, and the individual amp itself. But from your description, I'm with you, if they are tied together at the both the battery and the helm, something is not right. To my mind this type of a setup would actually decrease the protection provided by the fuses. I'm thinking if a short occurred in one of the two runs, the fuse in that run would blow (per design) stopping the flow of power to the helm via the first run, but power would still be provided from the battery via the second run to the helm, and all the way to the short in the first run, eventually causing the second fuse to blow. The eventually could be milliseconds, but that whole time the helm is upstream from the short. Sounds like a recipe for trouble.
 
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Jim, you are correct on the potential for problems with this set-up. Now that I am retired the helm is going to get a complete re-wiring, something along the line of the way I would do a street rod. Maxi-fuse at the battery and a nice fuse panel under the helm. Steve
 
Chateau Vinne said:
I am not as ambitious as the rest of these fine posters... but in looking at your initial question, I paid the dealer $142.50 for one and a half hours of labor to install a dual battery set-up in my boat before he dropped it in the water last year. I provided the second battery and tie down box and told him where I wanted everything. In addition, he charged me for the switch, wire, and copper lugs on top of that. So, you can do it yourself and save on the labor... lots of guidance online. Or, pay about what I did for the labor. Either way, you have to buy the, battery, tie down, and associated switch/wire/parts. I would have spent much more time than an hour and a half researching how to do it myself, buying parts, worrying if I was doing it right, etc., etc.
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My dealer wants to charge me $400 which includes the new battery. How much was your total including the battery? Thanks.
 
Here's my guestimates:

Generic Dual Purpose Group 27 battery with battery box, $100

Blue Sea Systems switch, $40

Battery Cables, $40

Installation, 1.5 - 2 hours

This would get you a basic second battery with switch install, assuming placement is right next to exiting battery (probably in changing room area). Any upgrades in Battery make or size, battery location, or additions of an Automatic Charging Relay would increase costs in parts and installation.
 
Jim_R said:
Here's my guestimates:

Generic Dual Purpose Group 27 battery with battery box, $100

Blue Sea Systems switch, $40

Battery Cables, $40

Installation, 1.5 - 2 hours

This would get you a basic second battery with switch install, assuming placement is right next to exiting battery (probably in changing room area). Any upgrades in Battery make or size, battery location, or additions of an Automatic Charging Relay would increase costs in parts and installation.
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and I obviously add that to the $142.50 stated above?
 
Yes, that's about right... I don't remeber what the cables cost, but the numbers above were spot on for the battery, box, and switch. And, as I stated earlier it took them 1.5 hours to do the job. Four R's must have been a service manager at a marina in a previous life... ;)
 
Chateau Vinne said:
Yes, that's about right... I don't remeber what the cables cost, but the numbers above were spot on for the battery, box, and switch. And, as I stated earlier it took them 1.5 hours to do the job. Four R's must have been a service manager at a marina in a previous life... ;)
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after I retired from being a rocket scientist!
 
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