Booster pack for boat trailer winch?

Saxe Point

Well-Known Member
I’ve got an old Powerwinch 912 boat trailer winch that came with the boat the boat and trailer When I bought them. Because I moor my boat pretty much year round, I don’t use the trailer much. I take it out about twice a year for clean up and maintenance. But I’m also going to trailer to a few different destinations a few more times a year. Still not a lot of planned use.

The deep cycle 12 volt battery that powers the winch sits in a battery box mounted just below the winch. It’s almost done. Rather than getting a new one that just sits around and might get used at most 4 to 6 times a year, I was thinking that I might be able to use my Motomaster booster pack. It’s a 12 volt AGM battery that has 700 cranking amps (picture below).

I can’t see why it wouldn’t work, but I’m wondering if anyone has any experience doing the same thing or has any thoughts on it?
 

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Actually, if you intend on keeping the truck. I assume you have to tow and launch your boat, it is not hard to wire your truck with proper size cable and a breaker. I have done 2 myself in the last year. Not much to it really, just crawling around under the truck. Lordco had all the connectors and everything needed.
 
Your booster pack is spec'd at 35 amp hours. That would be brand new, under ideal conditions. Many 12 volt winches that are optomistically rated for a 2000 # pull, draw over 100 amps under load. That's why the battery is kept close to the winch. So theoretically your booster pack, with good connections, should easily power the winch for the few minutes needed to haul your boat onto the trailer. You would likely want to keep your pack fully charged, though.
 
Your booster pack is spec'd at 35 amp hours. That would be brand new, under ideal conditions. Many 12 volt winches that are optomistically rated for a 2000 # pull, draw over 100 amps under load. That's why the battery is kept close to the winch. So theoretically your booster pack, with good connections, should easily power the winch for the few minutes needed to haul your boat onto the trailer. You would likely want to keep your pack fully charged, though.

Thanks. I think I’ll give it a try. It really is only a few minutes of actual pulling. It might take at most five minutes under load to winch the boat onto the trailer. According to the manual, a 60 amp breaker is called for when using this winch. So I’m not sure if it will draw 100 amps as that would trip the breaker wouldn’t it?
 
Thanks. I think I’ll give it a try. It really is only a few minutes of actual pulling. It might take at most five minutes under load to winch the boat onto the trailer. According to the manual, a 60 amp breaker is called for when using this winch. So I’m not sure if it will draw 100 amps as that would trip the breaker wouldn’t it?
Correct. If the manual specifies a 60 amp breaker, that would be somewhat more than the actual draw under load. The winch may be rated for pulling around 1200# rather than 2000#, hence the difference in amperage draw.
 
I have 220 HP that puts the boat up against the winch stand very effectively.
 
You will be banned from the Discovery Harbour ramp if you power hard onto your trailer.
Not an issue at high tide, but it undercuts the concrete ramp by blowing out the gravel bed at low tide.

Although I may dock aggressively at the ramp, I am quite passive in putting the boat on the trailer.
 
You will be banned from the Discovery Harbour ramp if you power hard onto your trailer.
Not an issue at high tide, but it undercuts the concrete ramp by blowing out the gravel bed at low tide.

Although I may dock aggressively at the ramp, I am quite passive in putting the boat on the trailer.
Yep, that's why I put my asbestos underwear on before I hit the post button. It's not an issue where I launch and no one complains when I'm out in 5 minutes.
 
The old man pulled a 23 hourston up on a roller trailer every weekend for years with a booster pack. Full pull no rest. And rarely had the trailer deep enough. Go for it
 
Can't help myself following the offtopicness but...
I read a trailer manual years ago and it called the winch an, "Emergency Recovery Device", indicating that powering on was the preferred method.
 
I’ve got an old Powerwinch 912 boat trailer winch that came with the boat the boat and trailer When I bought them. Because I moor my boat pretty much year round, I don’t use the trailer much. I take it out about twice a year for clean up and maintenance. But I’m also going to trailer to a few different destinations a few more times a year. Still not a lot of planned use.

The deep cycle 12 volt battery that powers the winch sits in a battery box mounted just below the winch. It’s almost done. Rather than getting a new one that just sits around and might get used at most 4 to 6 times a year, I was thinking that I might be able to use my Motomaster booster pack. It’s a 12 volt AGM battery that has 700 cranking amps (picture below).

I can’t see why it wouldn’t work, but I’m wondering if anyone has any experience doing the same thing or has any thoughts on it?
I have the same winch and just about the same pack. I use it everytime and it works great.
 
If you're planning to keep the truck and are increasing your trailering, I'd wire into the truck battery to add its power to the winch. I have a tandem axle dump trailer I use in my business and have a truck wired for this. Huge draw on the trailer's onboard battery will run it down in no time. Adding the truck battery (with engine running) makes it much better. Cost about $300 for the work, wire and fittings from an auto electric specialist. Wouldn't be hard to do yourself if you have the big crimping tool needed for battery cables.
 
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