Battery disconnect toggle switch?

Discussion in 'Wiring' started by smoreking, May 9, 2012.

  1. smoreking

    smoreking Member

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    Hey, So far I've never camped without shore power but I may later on. I do have a battery that was hooked up stock with 12 guage wire. I added an inline 15 amp blade fuse and a metal toggle switch so I can disconnect without opening box. The switch says 20 amp and the in line fuse came with 15 amp in the 12 gauge wire. Will the switch and fuse carry as much current as the 12 guage wire? I see here on the portal that 10 guage is recommended. If I went to 10 guage wouldn't I have to bypass all of the factory wiring from the tow vehicle battery all the way to converter? Would a 10g wire hook to back side of truck 7-pin connector?
    [​IMG]
     
  2. ghacker

    ghacker Active Member

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    I think the 10ga recommendation you're referring to is in regards to the charge line from the TV so that your TV can charge the battery more effectively. It's not for the PUP wiring. Your battery switch is between the battery and the PUP, right? BTW, I'd replace that switch with something that's waterproof. Harbor Freight has some cheap ones for @$4-7 or you could get a marine switch for @$20-30. Blue Sea or Guest are solid brands.
     
  3. JT2

    JT2 Member

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    12 gauge wire is fine for 20 amps, but no more. The 15 amp fuse was probably selected to allow a little electrical lee-way before any trouble occurred. The wiring is 20 amp, the switch is 20 amp...I'd put a 20 amp fuse in place of the 15 A and call it good. The circuit should work quite happily unless you're running at the limit for any length of time.

    For 99.98% of battery uses when boondocking, you won't approach that 20A limit if you're careful about turning things on and off. No need to rewire the trailer with #10 wire unless you've got some serious 12v loads.

    Charging the battery from the TV WILL require at least #10 wire, and thicker if you can do it. (Voltage drop over distance and all that.)
     
  4. smoreking

    smoreking Member

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    Thanks for the replies. I will get a waterproof switch, I didn't think of that. As for the rest, I'm unsure of what I need. It looks like all of my wires are 12ga to and from plug on truck and into harness for the pup. Looks like from pup connector everything goes straight down frame rail toward pup with only a "spur or side wire spliced in" going off the side to battery. I have 10ga from frame to battery for ground, but the only wire for hot that I have is this spur. I keep battery charged at home anyway and I won't be relying on truck to charge battery on boondock trip or anything, but I was hoping I'd be set up to use fridge on 12V while traveling. Are you guys telling me that 12ga from battery to fridge will keep fridge cool but my battery will go dead in couple hours as result?
     
  5. campfreak

    campfreak Active Member

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    Yep. Well, maybe more than a couple hours, but it will run it dead fairly soon. I think the fridge on 12v draws about 10 amps.
    I used a switch like Ruide did. Works fine, pretty cheap. Here's a link:
    http://he-ruide.smugmug.com/Electrical-Moditications/Battery-Modifications/3483731_cG3LwL#!i=196116053&k=SHL4k
     
  6. mv520

    mv520 Member

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    For reference, my Dometic fridge draws 6.7A when running off 12V. So lets say you have (just for example) a 100 AH capacity battery. Your not supposed to go down over 60% of total capacity so that's 60 Amp hours you can use. So 60/6.7=9 hours to a dead battery. Your mileage may vary depending on your fridge, battery, and how new it is.

    One other comment just for consideration. I suspect the toggle switch is not rated for use in an explosive atmosphere. i.e., IF there were to ever be hydrogen gas buildup inside the barely-vented case, and you flipped the switch, the switch contacts are not sealed from the outside of the switch body itself and a minute spark between them as you make/break the circuit could, possibly cause an explosion. I know, not very likely, odds are it will never happen, and yes a switch rated for an explosive environment is very $$$, etc. but just feel compelled to point that out. It only takes bad luck one time. Some people mount a separate electrical box outside the battery box and put the switch in it. Not as simple or sleek, but technically a safer solution.
     
  7. campfreak

    campfreak Active Member

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    I mounted mine underneath, so it's mostly out of the weather, and hidden, so there's no funny business.

    Greg
     
  8. BajaPup

    BajaPup New Member

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    Your link got hosed up somehow, but it still worked for me. Here's the same thing, all hypertexted up:
    http://he-ruide.smugmug.com/Electrical-Moditications/Battery-Modifications/3483731_cG3LwL#!i=196116053&k=SHL4k

    Thanks for that. I haven't looked at all of Ruide's stuff and missed the battery box. Funny thing, I was already thinking about the same setup, including the Python lock. A shallow, single-gang, wet location box will be perfect. I may even use a double-gang if it looks like my wiring could benefit from it. One for a master disconnect, and one for everything but the breakaway switch. I may not even use my Harbor Freight disconnect.
     
  9. smoreking

    smoreking Member

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    Thanks again. I will get a better switch.
     
  10. cpd1343

    cpd1343 New Member

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  11. BajaPup

    BajaPup New Member

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  12. Oldernie

    Oldernie Always searching for AZ big Elk

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    Looking through HeRuide's setup, it appears that he used 120 volt stuff, albeit a heavy duty switch. Do you electrical guys agree that this is ok for our 12v setup?
     
  13. Dubbya

    Dubbya Wherever you go, there you are...

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  14. campfreak

    campfreak Active Member

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    That's what i used, so far, so good. regular household toggle switch inside a weather resistant box. I forget what it cost, but it was pretty cheap. 5 or 6 bucks total at HD, I think.
    I think a lot of people get carried away with their heavy duty cutoff switches. Those things are meant to run starter amperage thru them. Not necessary for a popup cutoff switch.

    Greg
     

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