Winch battery charging

Discussion in 'OnBoard Electronics & Controls' started by Deering, May 7, 2019.

  1. Deering
    Joined: Feb 2005
    Posts: 386
    Likes: 13, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    Hi all,

    I’m sure this has been beaten to death here in previous conversations but a quick search didn’t yield the answer I’m looking for...so here goes.

    I have an electric winch that operates a stern lift gate (tailgate for us simple folks). The max rated amperage draw is 180 amps (12v) at stall. The distance to the panel is 30+ feet (one way). That requires a big (expensive) cable, coupled with some significant space challenges in my crowded cabinet. The winch would run infrequently, a few times a day at most, and only for maybe 30 seconds at a time.

    My plan is to install a battery next to the winch. I have a small AGM battery typically used for motorcycles and ATVs. It works great! Plenty of juice for the winch. So how to charge it?

    If I just run a charging circuit from my distribution panel, I run the risk of pulling too much current through that small wire, say 12 gauge, when the winch is operating, especially if the winch battery fails for some reason. I assume the breaker in my panel would prevent that.

    Another problem is that my panel would always be energized even when the switch to the house bank was off, until I shut off the breaker to that circuit, which I of course would forget to do. And the small battery would quickly be drained by anything left on.

    And finally, and this is where I get fuzzy, I’m not clear what issues would arise while the house bank is being charged. Could my little battery get toasted?

    So here’s my idea. I plan to run a 120v circuit to an outlet in a stern cabinet. Is there any reason why I shouldn’t just install a 120v battery trickle charger/maintainer on the small battery? That would eliminate all sorts of issues with battery isolators, switches, fusing, charging...and it would be cheap! I could buy a trickle charger for about $25 at any auto parts place. Many are weatherproof, and it would be installed in an enclosed space. I won’t need to recharge it fast given its infrequent usage, and the drawdown on the battery wouldn’t be that deep if I only run it for less than a minute. A one amp charger would meet the need just fine.

    If the trickle charger failed, or my inverter failed, and the battery died, I have other ways to raise the tailgate in a pinch.

    So where is the flaw in my thinking? I know there must be one. Nothing is that simple (in my experience).
     
  2. missinginaction
    Joined: Aug 2007
    Posts: 735
    Likes: 61, Points: 28, Legacy Rep: 512
    Location: New York

    missinginaction Senior Member

  3. Barry
    Joined: Mar 2002
    Posts: 1,086
    Likes: 63, Points: 48, Legacy Rep: 158

    Barry Senior Member

    Make it easy and use one of these, add a few more feet of cable, Checks the boxes, no power to the winch wiring when not in use, additional winch battery not required, charger not required, 120 source not required,

    Warn 32963
    The line is energized from the battery to the winch only when the winch operates
     
  4. philSweet
    Joined: May 2008
    Posts: 2,190
    Likes: 134, Points: 63, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    I'm assuming the winch itself has it's own built-in contactor and wired or wireless control system, and you just need to get the juice to it.

    You don't need to or want to pull power through your panel 30 feet away. And you probably don't need an additional battery either. How far, round trip, would the run be to the nearest battery in the boat, be it a start batt or house bank? You just need decent fuses, and optionally a relay control, on this feed. I wouldn't want to pull this off of the batt that has critical nav functions, though. Sailed one boat that had the electrocompass powered from a start battery. It lost nav everytime you started the port engine. Found this out at night, in the rain, approaching a very narrow channel in the Bahamas. Figured it out when I heard the echo of the engine off the cliffs.

    This is much like Barry's idea, but the Warn kit isn't suitable for boats because the type of start relay included in it really isn't up to snuff and I don't like the power connection. Use normal marine primary wire and marine fuses at the battery, and a beefy marine starter solenoid if desired. If you go with the solenoid to prevent monkey business, run the solenoid leads from your DC panel or other protected location.

    If the winch doesn't have its own contactor and controls, and you need to reverse the power to raise and lower, please ignore everything written above.
     

  5. Deering
    Joined: Feb 2005
    Posts: 386
    Likes: 13, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    Thanks all for the ideas. I decided to go with the battery charged using a Xantrex echo charger, from my starting bank. The charger will only pull current when the starting battery voltage is above 13v (being charged) so it won’t drain my start battery. Current is limited to 15 amps so the wiring can be small. And the charging is independent of the starter battery charging so it should protect the winch battery from being overcharged.

    This seemed to be the most robust and simple solution that didn’t break the bank. The entire solution - charger, wiring, and battery cost about $225 total.
     
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