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winch/battery draw

Discussion in 'The Garage' started by nicotine, Feb 25, 2004.

  1. nicotine

    nicotine 1/2 ton status

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    alright i am going to get a mile marker 9000 or 12000lbs winch and my question is will i need a dual batterie setup or just one good battery and a high output alternator? or what? it say "Amp Draw is 55 amps" on the mile marker 9000lbs and "Amp Draw is 65 amps" for the 1200lbs. how you guys set yours up would be helpful and any problems you had occur? /forums/images/graemlins/thumb.gif
     
  2. lukebaby1

    lukebaby1 1/2 ton status

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    Your amp draw will go up considerably when you put the winch to its rated load or below. If used intermittenly and in short sessions, you should be allright with one battery. You just have to let your battery charge a little after using for say three or four minutes under a pretty good load. If your belt starts squealing on your alternator, then you may want to look at getting a dual set up with an isolator. /forums/images/graemlins/thumb.gif
     
  3. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    You'll want the biggest battery you can fit in the tray. You want a large battery because the bigger it is the faster the chemical reaction can happen. The faster the chemical reaction can happen, the more current you can get without a voltage drop. The bigger the battery the more acid, the more surface area, and the faster heat can be dissipated.

    Ideally, you'd want a 1100CCA battery. I'd prefer to run two 650s though (more battery real estate to get rid of heat and reaction to happen).

    The bigger the alternator, the faster the recharge. Plus, the alternator will do its best to keep the voltage from dropping too much.

    What Mile Marker has listed on its site is no-load amp draw. IE: when you're spooling the cable in or out.

    Mile Marker's big motor is 5.4hp. 5.4 hp * 746 watts/hp = 4028 watts. 4028 watts/12.6v = 319 amps.

    If you could run dual alternators they tend to charge at .2v/cell more than the cell value. That'd be 13.8v on a typical 6 cell battery. So if you had dual 140 amp alternators you could put out 280 amps at 13.8v which is pretty close to the 4028 watts that the motor can consume.

    Keep in mind that a single battery often has a voltage drop when a lot of current is required. Usually a good battery will drop down into the low 11v range. That means you're drawing even more current... in the 370amp range.

    I'm using double aught (00 gauge) wire. It drops 1v at 17 feet at 400 amps. I'm also using 350 amp disconnects. I have two 700CCA batteries that are connected in parallel using a Ford starter solenoid and 2 gauge wire. I think it'll be sufficient.
     
  4. Executioner

    Executioner 1/2 ton status

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    Good post, but your #'s are not real world, you forgot
    efficiency ! And mech. HP to electric can easily be
    20-40%, so that winch motor is going to draw alot of
    amps.
     
  5. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    "Crappy" DC motors are 85% efficient. I don't know about the series wound ones.

    We don't care about losses after the output shaft.

    Winch motors are rated at their peak horsepower at peak efficiency at the rated voltage at a rated rpm as far as I know. It isn't the continuous rating. The continuous rating is usually 8-10 times lower.

    I've seen a Warn winch with a 4.6hp motor draw over 600amps near stall before. But under normal pulls it stayed below 400...

    So yes, they can draw a lot of current... but it's usually pretty peak-infested from what I've seen. That's why I say plan on what the winch motor is rated at. If you under-prepare you're destined for failure. 2 gauge wire running from your battery to your winch isn't going to hack it in extreme situations.
     
  6. bigjbear

    bigjbear 1 ton status Staff Member Moderator

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    Clarify please; Are you saying you replaced the cable from the winch motor to the battery w/ "00"? Or did I missread that? Do you think this is a nesscarry/benificial mod or did yours just need replacement? TIA.
     
  7. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    I'm running a multimount setup so I can take the winch off and also use it at the front and rear. 2/0 wire is marginal for the distance I'm running the winch to the rear of the truck.

    At 400 amps and 6', 2 gauge wire drops 1v. That's a lot of voltage (and therefore power) to lose in just 6' (seems to be about the average distance for permanently mounted winches). The lower the voltage the less efficient the motor. By increasing the wire to a double aught (2/0) you'd only lose .5v in that same distance.

    Winch wiring is kind of a vicious cycle. Let's say the winch wants 300amps and 12v. The wire says it'll only give you 11v because of so much current flow. Well, since the winch still wants the same amount of power the current goes up more... dropping the voltage more... driving the current up more... until the motor is happy in equilibrium. I've seen winches go all the way down to 8v at the terminals on the winch.

    Anyway, the moral of the story is that the bigger the wire the more easily your winch works and the happier your charging system will be.

    If you don't mind spending the ~$2/foot for some 2/0 welding cable and about $10 for new ends then I think it is a worthwhile thing to do.
     
  8. bigjbear

    bigjbear 1 ton status Staff Member Moderator

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    Good points, thanks for taking the time to do the math. Sounds like a worthwhile mod.
     

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