Where to pick up power

Discussion in 'Wiring' started by shaun77, Oct 30, 2011.

  1. shaun77

    shaun77 New Member

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    I just wired my 4 way to seven way adapter, now I need to pick up power to charge the pup battery. The guy at Uhaul said 12g wire to the battery with a 10amp inline fuse. I've seen other posts though saying wire it to the underhood fuse box on the IGN. Who's right?
     
  2. johnlely14hw

    johnlely14hw New Member

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    I did it from the ligth cables in the trunk, works fine. When the car is off, won't drain the batt.
     
  3. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

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    Actually, I'd suggest 10 gauge for the power line, especially if you ever plan to run the fridge on DC while driving.
     
  4. rabird

    rabird Howdy!

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    Either works.

    I first wired 10 gauge to a 30A shortstop self resetting circuit breaker at the battery. I put the wire in split plastic loom to protect it. It was always hot.
    Year or so later I found I had a blank circuit controlled by the ignition (sun roof circuit) and used an add a circuit to wire a 30A relay to control the charge line (on/off with IGN).

    I doubt anyone that has used 8 gauge regrets it (less voltage drop)!

    This guy went with #2 welding cable $$$$$
    http://www.damouth.org/RVStuff/TrCharge.shtml
     
  5. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

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    I'd have to agree about the 8 gauge and should have said "at least 10 gauge or better".
     
  6. bruceac1

    bruceac1 Member

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    [2C] I was originally going to ask if there was any worry about draining the TV battery while camping, but I remembered that you unhook the pup from the TV while camping. They sell a dual battery system so the camping battery, can't discharge the TV battery. Someplace I have a schematic of a dual battery circuit. Now to just find it amongest all my books.
     
  7. shaun77

    shaun77 New Member

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    I went ahead and wired 10g with an inline fuse from the B+ pole on the fuse box. Two questions though, first what size fuse for the inline? and two, I'd like to have it wired to the ignition as previously stated, how is that done? It works fine as is I would just hate to forget to unplug it one day!
     
  8. robctry69

    robctry69 New Member

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    leave it hooked to the bat and install a relay is the best way to do it
     
  9. shaun77

    shaun77 New Member

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    Thanks Bupkis! What size fuse is used for the add a circuit? Or is that dependent on which fuse site I use?
     
  10. rabird

    rabird Howdy!

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    My add a circuit was rated 10A so I used a 10A fuse to power the 40A relay.
    I used the add a circuit in an unused circuit, it could have gone in a used circuit that already had a 10A fuse.

    The add a circuit has 2 fuse holders, one for the existing circuit and one for the new circuit.

    I believe the largest fuse for 10 gauge is 30A. My PU is fused 20A at the battery and 10 gauge wire.

    Relay and circuit breaker
    [​IMG]
    Add a circuit
    [​IMG]
     
  11. goody59

    goody59 Member

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    If you want sufficient battery/alternator power to rear of tow vehicle minimum 5 AWG or better still 3 AWG to prevent voltage drop and to be able to charge trailer house battery. Anderson plug connection to the house battery in the camper. Fused at both batteries. A separate negative run of same size cable better than relying on earth of vehicle chassis too. A separate cable joined into the anderson plug on rear of vehicle 5 AWG to your 12v 3 way fridge supply will allow you to operate the fridge on 12 whilst driving but you must disconnect that large 10 AMP supply drain when motor is not running or you will end up with a flat start battery.
    I have researched this subject very thoroughly and know what I am talking about. I have don this to my set up recently. It is expensive but it works for keeping trailer house battery charged as you drive and fridge running on 12V. The fridge will not operate on much less than 12 v (Voltage drop)
     
  12. Wrenchgear

    Wrenchgear Near Elmira, Southern Ontario

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    I used a 30 amp auto-resetting circuit breaker, hooked onto a #10 wire going off the batt + of the TV straight to the 7 pin round. I too was worried about killing the TV batt if not unhooked, so I used a relay exactly like what Bupkis is showing in his first picture. The relay is now between the batt + and the #10 wire. I have the relay turning on and off with my running lights of the TV. This keeps the Pup batt separated from the TV batt if the running lights are off. I couldn't find a spare circuit, controlled by the ign key, in my TV that was easy to get at to control the relay. I thought if I have the relay come on with the running lights, I have great control over the charging of the Pup batt.

    Here's the scenario... I'm up at the park for a full week dry camping. As the week goes on, my Pup batt gets lower and lower on charge because its not plugged into any type of charger. The batt in my TV is also going down from a week of doors being left open and interior lights on for extended periods of time. The van won't run for that hole week.
    The week is up and I pack up for home, hook the Pup onto the TV and start to pull away. The alt in my TV says "holy crap!!! what just happened". It has to start charging the TV batt, charge the Pup batt, and provide power to run the rest of the vehicle all at once. Thats pretty tough on an alt. They get pretty hot and reduce the life span.
    So I leave around supper time for my long drive home. Its still light out so I don't need my headlight system to be on for awhile. I drive for and hour or so and let the TV batt get fully charged, now I flip on the head lights, (running lights included), and this turns on the relay to pass power to the Pup batt for charging. The alt is much happier now.
     
  13. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

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    When I'm camping I turn the interior TV lights off so they don't come one every time the door is opened. If I need them I switch them on for the moment and then off again right away. That helps a lot to protect the TV battery.
     
  14. marcham

    marcham New Member

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    I think I used either #8 or #10 wire, a 20A auto reset fuse close to the battery and a battery relay switch in the back of the truck. The relay is tied to the vehicle's running lights, so all I have to do is turn on the lights if I want to charge the trailer. Note that you won't get a whole lot of current through, considering the length of the cable run. I tried running the DC fridge but at 10A, the wiring didn't keep up and it depleted the battery.
     
  15. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

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    Are you saying that you attempted to run a DC fridge on the TV battery? Bad idea for two reasons. First, the TV battery is not deep cell and not intended to sustain long power draws. Its purpose is to provide brief bursts of power for starting. Second, never run a fridge on DC power on any kind of battery unless you have the proper wiring system and gauge of wire in the TV and you are driving down the road, allowing the TV electrical system to recharge the PUP battery. If you run a fridge on DC while camping (no connection to anything else) you will kill the PUP's battery in a few hours. Even a deep cell can't take the huge power draw for very long. Always use AC electric or propane.
     
  16. marcham

    marcham New Member

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    ... ran the 12VDC fridge while driving ... read my post, you'll see that my 12VDC to TV battery won't work unless the vehicle's lights are on.
     
  17. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

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    I did read your post and that's why I made the point. Your post does not say that you were driving or have to be driving. It says:
    You can see how this wording could be interpreted in ways other than the one you meant.
     
  18. turborich

    turborich Active Member

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    8 gauge wire with a 30 amp thermal breaker will work great & keep your fridge going while in tow.
     

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