Winch vs battery capacity

[CCW 1,333]

This summer I have a job that needs to be completed.  Six, 350 pound concrete blocks need to be lifted six inches off a dock, pivoted over the water where they will be lowered ten feet to the bottom.  Here is what I have in mind.

Using my 2000 lb, 12 volt winch which has a static lift capacity between 940 and 2000 lbs depending on amount of cable that is played out I plan to raise the block off the dock and pivot it over the water where I will lower it into place.

Here is the question.  The spec for the winch call for a 650 CCA battery.  At 2000 lbs of static lift it draws 120 amps.  Will the draw of lifting 350 lbs be around 25 amps and will the 650 CCA battery be able to repeat this process six times without being recharged?  Below is the static lift capacity based on the amount of rope played on the winch drum.

 

Rope Layers	Capacity (lbs)	Total Rope on Drum (ft)
1st Layer	2,000	6-1/2
2nd Layer	1,630	14
3rd Layer	1,380	23-1/2
4th Layer	1,190	35
5th Layer	1,050	47
6th Layer	940	50

 

Any thoughts?  Questions?  Clarifications needed?

 

[ri702bill 8,933]

You may wish to have a second battery in parallel to double the amps. Had to do this on my old Jeep Pickup for plowing. Electric (starter motor) ran the pump tp lift, plowing at night and the heater / defroster on necessitated it.

 

Lift is tough, lower is easy...

[ebinmaine 70,494]

What kind of vehicle is doing the lifting? 

 

HOW does the pivot happen?

 

Pics of that would be neat. 

 

[wallfish 17,445]

Use a ****** block pulley instead of direct cable to the concrete block. It might be slower but will certainly make lifting it easier.  Or by using block and tackle you could do it by hand with a rope.    HAAA! Guess you can't use the word sn   atch on here

 

Edited March 19 by wallfish

[oliver2-44 10,298]

To answer the question we would need some type of electric motor/ torque curve for the winch. Winch motor amp-power consumption is not linear.  you can’t just divide the amps by the % load. The motor high starting current draw and motor losses would apply at the 1st load lifted no matter the weight. 
As wallfish said use a pulley 

[c-series don 9,414]

Assuming some type of equipment is going to transport the blocks out onto the dock, can you use a mini excavator for this job? 

[CCW 1,333]

14 hours ago, c-series don said:

Assuming some type of equipment is going to transport the blocks out onto the dock, can you use a mini excavator for this job? 

 

Unfortunately not an option.

[Handy Don 13,321]

From your description, the blocks will already be on the dock.  It seems they’d need be lifted only a few inches--a matter of a few seconds work--to get clear of the dock for swinging outward and lowering from there. Lowering will need only a fraction of the lifting amperage.

[wallfish 17,445]

Mount this to a Wheel Horse and get the job done IN STYLE. Plus you'll have it for any future needs.

https://www.harborfreight.com/automotive/truck-bed-accessories/truck-cranes/12-ton-capacity-pickup-truck-bed-crane-with-hand-winch-61522.html

[SylvanLakeWH 27,351]

 

Works great!!!

 

 

[adsm08 2,595]

On 3/19/2025 at 6:56 PM, wallfish said:

   HAAA! Guess you can't use the word sn   atch on here

 

 

Auto-censors are the worst. No context is taken into account, and most are overley sensitive to stupid things.

 

I've seen, on another site, COVID and pandemic censored, "die" and "dead" in relation to a car battery, "trump" as in "trump card". But the same site allows all sorts of profanity.

 

There was one post on that site that I stopped even trying to read because the auto-censor had removed so many words there wasn't enough to even figure it out from context.

[adsm08 2,595]

I'd be looking into what you can do to get something out there to charge the battery during operation.

[CCW 1,333]

@SylvanLakeWH @wallfish

This might actually be the solution, just mounted on the dock in a different way.  With the hand cranked winch no battery issues and the price is right.  Also will be able to use around the yard to save my tired back. Thanks.

 

[CCW 1,333]

@adsm08  If you find something that would be great info to have..

[CCW 1,333]

On 3/20/2025 at 12:09 PM, Handy Don said:

From your description, the blocks will already be on the dock.  It seems they’d need be lifted only a few inches--a matter of a few seconds work--to get clear of the dock for swinging outward and lowering from there. Lowering will need only a fraction of the lifting amperage.

 

This is correct.  Have to raise the blocks about six inches.

 

Edited March 22 by CCW

[adsm08 2,595]

23 minutes ago, CCW said:

@adsm08  If you find something that would be great info to have..

 

 

I am sure that I could come up with a solution, I would just need some information about the site.

[SylvanLakeWH 27,351]

1 hour ago, CCW said:

@SylvanLakeWH @wallfish

This might actually be the solution, just mounted on the dock in a different way.  With the hand cranked winch no battery issues and the price is right.  Also will be able to use around the yard to save my tired back. Thanks.

 

Great!

 

Had a wheelchair bound neighbor who used same thing to get in and out of his pontoon boat... He bolted it right to his dock. Worked like a charm.

[CCW 1,333]

Update - Looking at the suggestions above I decided to go with the pickup truck crane.  Currently going through the design and testing process and on Tuesday will pick up a 350 lb block of concrete for further testing.  Looking at the second photo you can see five WH suitcase weights on the end of the eight foot 2x8s. Base did not move at all in this test lifting the front of my 312-8.  My plan is for three, six or eight foot, 4x4s to be attached to the double 2x8s.  One at each end where the edge of the dock is and one just in front of the crane pedestal.  If more counter weight is needed then helpers can stand on the 2x8 base.  Also the 4x4 cross members at each end will be clamped to the dock.

 

Since all your expertise came into play on this project I am open to more suggestions.

 

 

Edited Wednesday at 09:21 PM by CCW

[Handy Don 13,321]

I think you are definitely on the right track here. Looking good!

Please don’t ignore the forces in play at the base of the vertical member of the crane where it attaches to the wooden base. Consider grade 5 or 8 for the bolts and perhaps a metal plate on top and bottom of the wooden beams to distribute the load across a wider area. 

[SylvanLakeWH 27,351]

I would also test lift off the side of it as you intend to " pivot" the load...

 

Also, lifting the tractor keeps the load static because of rear wheel contact. Dead load swinging is a true test of intent...

 

 

 

[Handy Don 13,321]

23 minutes ago, SylvanLakeWH said:

I would also test lift off the side of it as you intend to " pivot" the load...

 

Excellent point. Using only nails on any part of the wooden base would be risky, as they could pull out when the force is “up” instead of “down.” 

The carpenter that helped my dad build his house frequently reminded us that “You can use nails for building a house but for anything else, use screws or bolts.”

I was eight years old and it stuck, so that tells you how often he said it! 

[CCW 1,333]

@Handy Don & @SylvanLakeWH

Thanks for the input.  The bolts are 1/2 inch grade 5 and there is metal angle iron on the underside of the 2x8.  Next step is to bolt on 9 foot 2x12 cross members at each end and just behind the crane if needed.  When in use on the dock helpers can stand on the 2x12 to add any needed counter weight.