Quote:
Originally Posted by iamnotahippee
So doing the math, my winch has a 1.5 hp motor, 1100 watts.
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One small deep cycle battery is rated at about 50 amp-hours. 1100 watts divided by 11 volts is 100 amps. Theoretically, one battery should run that winch for 1/2 hour, BUT no deep cycle battery will deliver 100 amps for very long.
Put in three such batteries, and each has to deliver only 33 amps. That should work much better. Connect them through an RV isolator as mentioned earlier. An RV isolator lets you work off the deep cycle batteries without pulling down the starting batteries. Then, when you start the engine, the isolator has the alternator recharge the deep cycles.
Your usage is drawing down your starter batteries. Starter batteries are designed to deliver large current for a couple of seconds, then get fully recharged. Deep cycle batteries are designed to deliver less current for a longer time.