Solar or car battery for winch?

train82499train82499 Registered Users Posts: 11
A friend is building a winch set up to pull his heavy boat (2000 lbs) up on shore in a remote location. He is not pulling it straight up, just up a gentle incline out of the water on a wheeled dolly railway affair.

The 12v winch he will use draws 40 to 80 amps at 1000 pounds and 350 plus amps at 6000 lbs. It will have thick cables obviously to the batteries like those to a car starter motor. The pull will be 4 minutes maximium but lets say 5 minutes.

I suggested he get two good 12v car batteries, hooked up in parallel, with good cranking amps, but he is thinking deep cycle marine or even solar batteries. My thinking is this set up needs lots of power for a very short period of time, because the winch works like a starter motor, hence car batteries.

Then to recharge - maybe he does this up one day, down another twice a week. I suggested that a 15 watt panel would be fine, maybe 30, on a poll, which a cheap CC to recharge. Or does he need something more sophisticated to build these up?

Car batteries have high cranking amps but I dont know how to figure out their amp hour rating.

What do you think?


  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Solar or car battery for winch?

    you are going to need bigger than car batteries.. get ones that are used in 4wd s or light trucks, get 2 and parallel them. No need to calculate anything . That will work perfect ,cables use as short a length as possible from batteries to winch (about3ft) size #4 .
    Your total ahr will be about 20. so you need a solar panel to replace the 240whr between uses.. a 20 to 30w panel will be ok use a 3a charge controller or a 5a one if yoy cant find a 3a one.
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Solar or car battery for winch?

    Large car or truck batteries, group size #27 should work, 2 of them with good cables made up, and a short run to the winch.

    But for charging, I think you would need a panel in the 50W range, to do some actual recharge, and keep the internal losses maintained. Car batteries, I think, may have higher losses, than conventional deep cycle batteries.

    A 100W panel, can only be counted on for 80 watts, unless you refrigerate it.
    80W (5.7A) for 4 hours a day gives you about 23AH back into the batteries.
    cut this in half for a 50W panel.

    80A usage for 6 minutes = 8AH used ? (am I figuring this right ?0)

    But self discharge of a pair of group 27, 100ah battery may need more than the 15W panel can supply.

    Also, many small panels, are "no name" from the cheapest vendor of the week, and may not give a long (20year) life. Add some bird poop, and a 50W panel may barely be enough. I'd rather have my batteries on float, than getting sulfated.
    Mikes 2 ¢ worth.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    gen: ,

  • train82499train82499 Registered Users Posts: 11
    Re: Solar or car battery for winch?

    Thank you both very much. I will investigate group 27 truck batteries. Will keep run to winch as short as possible - 18" max.

    Will scope out panels.

    Any idea re DIY pole mount plan drawings or sketches?
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Solar or car battery for winch?

    Deep cycle marine would be better. They give you the high current the winch needs plus if the solar system doesn't recharge the battery(ies) fast enought and they get run down too far. They will not get trashed like car/truck batteries.
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