Winch electric needs question

Quote: Originally posted by Flatfish

I’m putting in a land based winch to pull our boat up out of water and over a small sand dune into the woods for winter storage, about 100 feet. Winch is rated 3500 lbs. boat is a 14’ 3 bench row boat with a 100 lb motor, probably all told about 350-400#. Specs says winch will pull around 80-100 amps DC using those numbers. What kind of rated battery should I get given it’ll take around maybe 3-5 minutes to pull that distance? Thanks in advance! [Edited on 6-25-2025 by Flatfish]

An interesting question. My experience with electric winches on 4x4s is that they draw a lot of power from the battery. It is best to have the engine running at 2,000 to 2,400 rpm while operating the winch. The increased voltage from the alternator makes a big difference. A standalone battery will provide less power to the winch and deplete the battery quickly.

Another big variable in winching is the number of wrap layers the wire rope has around the drum. Pulling force is reduced with each additional layer of wrap. Fewer wraps = more pulling power and slower line pull speed, and probably the lowest power consumption.

Are you carrying a winch and car battery to the site? Purchasing the items for this sole purpose? Why not borrow the battery from a car?

I could likely figure out several better solutions for the task, particularly if you can get a motor vehicle (truck or ATV) anywhere close. You can use a pulley attached to a tree (aka: snatch block) to redirect a wire rope or nylon/polyester rope, or use it to double-back toward the beach. Then pull with the vehicle. Super easy.

An old climbing rope can be rigged with a "Z-pulley" system block for a 2:1 mechanical advantage.

A manual come-along would do the job easily, using a long rope or strap for extension. Several shortenings of the extension rope would be needed as you make progress.

Removing the outboard will make the job easier. Would you really want the outboard sitting out all winter?

The Baja way is to purchase a 6-pack of cerveza from Oxxo. Then invite 3 strong amigos to help carry the boat

Quote: Originally posted by richm

Heat will be a limiting issue. Check the battery capacity in Amp Hours and the specs for a maximum continuous discharge rate. The maximum continuous discharge rate for a lead acid battery is typically quoted as something like "C/20" where "C" is the rated capacity of the battery in amp hours. So for a 65 amp hour lead acid battery, C/20 would be 3.25 Amps maximum continuous discharge rate. Above this rate, connectors can melt, become more resistive, heat even faster, and have thermal runaway. Lithium batteries have much higher discharge rates in the 1C to 2C range. So a 100Ah lithium battery would be far better for this use. You can find good recommendations for lithium batteries on: https://diysolarforum.com/forums/beginner-friendly-plug-n-pl...

Quote: Originally posted by chippy

I would go with 650 CCA or more.

Quote: Originally posted by Tioloco

Quote: Originally posted by chippy   I would go with 650 CCA or more. Flatfish- This will be adequate. Just need to out the battery on a trickle charge maintainer when not in use.

Quote: Originally posted by Flatfish

Quote: Originally posted by Tioloco   Quote: Originally posted by chippy   I would go with 650 CCA or more. Flatfish- This will be adequate. Just need to out the battery on a trickle charge maintainer when not in use. Yup. We have a trickle charger. Thanks. For clarification for all who responded, the height from the shore to the cabin is about 12 feet. We have been using a hand powered winch for years, but two things. It was only a 12 footer and the 5 hp motor we could carry up and down the dune as needed. No problemo. Now it’s a 14 footer with a 20 hp motor and we are getting older 🤪🤪. No neighbor kids to call on later in the fall. This is Lake Superior btw. I’ll look into a 650 CCA or larger and talk to the guys at the battery places. BTW- access to the winch is out of reach of vehicles hence the question. Harbor freight had a killer deal on a winch and I snagged it up.

Winch install update

Here’s the finished install. Inflatable boat rollers coming tomorrow high should make the whole thing easier.