Prawn hauler blows up the fuse

[SpringVelocity]

Too bad hard to have discussion sometimes on here. I love my prawn puller thanks @Derby.

 

[ericl]

Sorry didn't realize you were a electrical engineer for NASA...…. and yes its a BC sport fishing forum.

sounds like you plugged some info into the blue seas app and now your a self proclaimed electrical wiz..

Well out of the blue he goes off on me & ended-up enjoying the taste of shoe leather IMO.

Bottom line here:the wiring as discussed so far (10/8/4 gauge) is not a safety issue; it is strictly a performance issue - thinner wire has more voltage drop per foot than thicker wire; the result will be less voltage getting to the puller with thinner wire.

This comes directly from the Scotty manual:

For wire run lengths up to 25 feet use minimum 12 Ga. wire, for runs of 25 – 40 feet use 10 Ga. wire. Wire smaller than the recommended gauge will not carry sufficient power to operate your downrigger at its rated speed and power, it will run noticeably slower.

 

[ericl]

I don't buy the plug/ electrical connection being the issue as many of you are using high power down riggers with 20+ balls. If your not tripping fuses every time it is possible the puller itself has issues.

If they are Scotty DR's they have an internal breaker of 20A, so yeah it could be the puller itself, but if you use a 30A fuse for a device rated at 40A, I'd suspect the under rated fuse first.
FYI in an earlier thread on this subject an Electrician pointed out that electric motors have a surge of current when they first start, and that breakers tolerate this temporary surge better than fuses.

 

[Breakin"even]

With the new higher amp./power Downriggers is there a better receptical out now?

 

[ericl]

Look at the bottom of this page:
http://scottypaddlesports.com/wp-content/uploads/2016/07/ChoosingTheRightElectricDR.jpg

Listed are the retrieve rates & associated current draw (measured in Amps) with each model of downrigger pulling various weights of balls. Max current with the HP models is 20 amps & the Marinco plug is rated for 40 amps. As such, from a maximum current amount, there would be no need for an upgraded plug. Of interest is that they have data for the older models pulling a 20# ball.

I had never seen the above info before I researched your question; thank you VERY much.
I had always thought the current draw on the older models was higher than published above.

 

[eric801]

Are we not creating another problem if we use 40 amp fuses (bigger wire etc) with our Scotty downriggers and pullers? Scotty is rated for 30. If we put a 40smp fuse in aren’t we going to damage our Scotty motors?

 

[Coyote Spooner]

Are we not creating another problem if we use 40 amp fuses (bigger wire etc) with our Scotty downriggers and pullers? Scotty is rated for 30. If we put a 40smp fuse in aren’t we going to damage our Scotty motors?

I believe they have an internal self resetting circuit breaker. Fuse protects the wire, from catching fire. Match the wire to the fuse and run length. There’s lots of info/graphs online, to properly size.

 

[kaelc]

Are we not creating another problem if we use 40 amp fuses (bigger wire etc) with our Scotty downriggers and pullers? Scotty is rated for 30. If we put a 40smp fuse in aren’t we going to damage our Scotty motors?

Haven't had an issue in 15 years, my friend believes Scotty’s 1100 are the best Marine technology ever invented. I now have the HP’s and no issues for 3 years.The female marinco(scotty rebrand them?) plugs on the other hand are an issue due to salt water corrosion and should be changed out/replaced when starting to have issues. Many melted fuses later….

 

[Max123]

I think this is an old thread, but it popped up. I don't have a prawn puller but noted a few things that didn't really come up in the comments (Assuming you have the right wire size and right fuse size):

-Check your connections! often when people strip wire they end up taking off a few strands, or don't get a good connection at the terminal. Likewise corrosion at the terminal can be a huge cause of voltage drop

-I'm not sure if people experiencing this problem with engine on, or off? If off, run your puller with the engine on. Let me illustrate with math:

1) A 30amp puller is likely maxing out at 24Amps continuous (30amps @ 80% rated), with a very short term bump for inrush current up to 30amps when you start the puller (anything longer than a second or two will blow the fuse). So assuming your battery is fully charged (12.6V), the math is 24amps x 12.6V = 302.4watts

2) If you start your boat, the alternator will bump up voltage to between 13.5-14.4V (lets use 14V for simplicity). So work the calculation backwards: 302.4W / 14V = 21.6A

So basically, with your engine off the prawn puller is going to be running at 24A vs 21.6A with the engine on. Its not a huge difference - maybe 13%, but it will help. Also, smaller batteries really have trouble with continuous/high loads and you will experience voltage drop which exacerbates the problem even further. Even if you aren't blowing fuses - turn the engine on, and idle it up to 2000rpm - it will make a difference.

 

[kaelc]

I think this is an old thread, but it popped up. I don't have a prawn puller but noted a few things that didn't really come up in the comments (Assuming you have the right wire size and right fuse size):

-Check your connections! often when people strip wire they end up taking off a few strands, or don't get a good connection at the terminal. Likewise corrosion at the terminal can be a huge cause of voltage drop

-I'm not sure if people experiencing this problem with engine on, or off? If off, run your puller with the engine on. Let me illustrate with math:

1) A 30amp puller is likely maxing out at 24Amps continuous (30amps @ 80% rated), with a very short term bump for inrush current up to 30amps when you start the puller (anything longer than a second or two will blow the fuse). So assuming your battery is fully charged (12.6V), the math is 24amps x 12.6V = 302.4watts

2) If you start your boat, the alternator will bump up voltage to between 13.5-14.4V (lets use 14V for simplicity). So work the calculation backwards: 302.4W / 14V = 21.6A

So basically, with your engine off the prawn puller is going to be running at 24A vs 21.6A with the engine on. Its not a huge difference - maybe 13%, but it will help. Also, smaller batteries really have trouble with continuous/high loads and you will experience voltage drop which exacerbates the problem even further. Even if you aren't blowing fuses - turn the engine on, and idle it up to 2000rpm - it will make a difference.

Yes, I was getting such a big voltage drop my chart plotter would shut down or restart, when pulling pots. Moving both downriggers to a larger agm house battery and a new outboard that produces more amps at idle should help.

 

[Max123]

Seems like weak output at 1000rpm idle was particularly the case on older motors - newer motors/alternators seems to be designed to provide higher output at idle (presumably to run more gear like this).