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Battery cut off switch for 2A draw LEDs?

2422 Views 6 Replies 7 Participants Last post by  seaspray24
I have a 22' sailboat with only an outboard--no alternator. I'm putting LED nav lights on my boat. If I'm drawing 1 amp from bow and stern LEDs and another 1 amp from a cabin LED, and will be using a 3 circuit 12v panel that comes with 3 separate fuses, plus a controller/regulator for the Sunsei solar panel, do I need:
1) a battery turn off switch for my 24 U-1 35Amp gel battery?
2) a negative bus?
3) a 20Amp fuse on the positive battery?
The guy that's doing the installation is saying NO to the turn off switch, bus and fuse at the battery? My Marine Electronics Power Squadron instructor is saying YES. The salesperson at W. Marine says NO--not necesssary for only 1 amp. I will not be running anything else on this battery. What do I really need for my situation? Thanks.
1 - 7 of 7 Posts
I think all you need is a fuse by your battery to prevent a short heating up a cable which can then start a fire or burn through your hull. That is mandated by ABYC and not doing so would be taking a silly risk. Even though the LEDs might draw only an amp, they will draw as much power as the battery can supply if they short out (i.e. get submerged in salt water or have a screwdriver accidently go across both terminals).
The battery cut-off switch is control any electrical fire(s). Not having one and having everything pretty much direct connect - means if somethings shorts / sparks etc - you have no way to isolate the source. 1 amp load by the manufacturer is nothing until when it it is shorted. Safety first - a main cut-off switch for the battery, circuit breakers, and then fuses.
It is hard to have too many fuses, cut off switches, breakers, etc ... unless they are blown, tripped, or switched, and you can't remember where they are. :D
A 20 amp fuse holder near the positive battery terminal should give you adequate protection against shorts and can be used to disconnect the battery by removing the fuse. A switch may help you control a fire from overheated wiring, but will not prevent one.
The fuse or breaker is sized based on the wire size first. Mounted as close to the power source as possible.
8 gage 40 amp, 10 gage 30 amp, 12 gage 20 amp etc, you want the breaker/fuse to trip prior to heating up the wire melting the insulation.
The next concern is to protect the application, selecting a fuse size that can be smaller than the maximum wire size fuse. A simple soulution is the automotive blade fuse where you can buy the holder with short wire leads. Use that to connect to the battery at the battery. Fuses are available from 1 to 30 amps...
A battery cut off switch is also not that expensive, the smaller simple ones with a red removable key are about $10.
Thanks to everyone that gave me such great advice.
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