New boat owner question

[John Radtke]

I have a 17 foot skeeter. On both batteries, the cables have little square blocks attached to the terminals. They have the words shortstop stamped on them. What are these and what is there purpose?

[Eyez]

Probably circuit breakers. They should have a little button in the ends that will pop out if they trip.


Eyez

[Dave in Mpls]

Eyez is correct, they are circuit breakers, However, I'm pretty sure that shortstop only makes auto reset breakers, so they will reset themselves. Hence, you may not find any type of manual reset button on them. Which batteries are they on, and what do they have stamped on them (40, 50, etc). You may have to disconnect the breaker from the battery and look at the underside to find this. This will be the amp rating for the breaker.

Regards

[John Radtke]

Dave... There is one on the positive post of the main battery and one on both the positive and negative posts of the trolling motor battery. Its a 12 volt system. They are stamped 50 amps. Can these guys go bad?

[Dave in Mpls]

Like any electrical/mechanical device, they can go bad. However, the chances of that happening are slim at best. You really don't need one on the starting/acc battery, as everything connected to it is fused already and, if it isn't, it's gonna fry long before 50 amps. Not really any reason for it, though, except in the rare circumstance you would chaff through one of the positive leads connected to it and make contact with a metal structure within the boat. The same is true with the one on the negative post of the trolling motor battery. Current flows from the + terminal, through the device (ie trolling motor) and back to the battery through the - terminal. That one can certainly be removed. I believe the connection to those breakers utilize a #10 ring terminal for connection. If you with to remove the trolling motor neg breaker, you will need to replace the existing ring terminal with a 5/16" lug. The same is true with the breaker on the starting battery, only it will require a 3/8" or 5/16" lug, depending upon the battery.

Regards

Regards

[mlc]

The circuit breaker you are talking about frequently comes as standard equipment with some accessories like a Panther Lift. Virtually any electrical circuit can be made to run without them as Dave described. However, they serve you as a circuit protector and I do not recommend removing them. Your equipment, batteries and wiring need all of the protection you can give them. Sorry if I've given unwanted advice but I've seen boats burn and sink because protective devices have been removed.

Take care,
mlc

[John Radtke]

Thanks for all the info.

[Dave in Mpls]

mlc-

Just curious what good a circuit breaker does on the negative side of a battery, other than introduce one more connection for potential corrosion problems down the road...

Regards

[cmb]

same as it would on the positive side!!!! it woul break the circuit!!

[Paul]

No, it wouldn't

Dave is correct, the breaker should be on the positive side of the battery, which there is. No need for one on the negative. Are the breakers in your house on the positive side of the panel, or the negative?

[mlc]

Hi Dave. You bring up a good point. I do not know why John's boat has protection on both the negative and positive side of the circuit(small boat dc voltage is not a specialty of mine). However,in larger ships and in the industrial world it is a common practice to place protection on both the positive and negative leg of a DC parallel circuit. I guess the trick is to figure out why the circuit designer put protection on both sides of the circuit. Perhaps some DC electricians/riggers out there have more specific answers that apply to our boats. The question for John to answer is "Why did the circuit designer protect both legs of the circuit?"

I operate my boat in both salt and fresh water. Salt water can be terrible on exposed electrical connection points. I have coated all of my connection points with a dielectric grease. I use the product made by Permatex. Alot of guys use good ol' Vaseline as a corrosion barrier. Just coat the back exposed area of the Short Stop and there will not be a corrosion problem.

Take care,
mlc

[mlc]

Paul, your getting direct current(vdc) and alternating current(vac) mixed up. In AC power the "polarity" changes at the rate of 60 times per second. The breaker panel in your house will have a "hot" side and a "neutral" side.

Take care,
mlc

[Dave in Mpls]

You, too, bring up an excellent point in coating the connections. I use the same Permatex product on all exposed electrical contact points. An ounce of prevention.....!!

Regards

[BruceNebraska]

Dave

I have to disagree with the Idea that you do not need protection on both sides of the Battery on the trolling motor. I hope that John has not made any modifications to the wiring on his boat yet. When you have a ungrounded DC (or ungrounded AC system for that mater) like your trolling motor. You need protection on both the negative and the positive of the battery. If your system is grounded (has a common ground) like your car, house or the main battery on your boat, you need protection on only one side (the source side).

I could go into the why’s and such but that would be a lot of typing. And I am poor at that at best. Please do not remove over current protection from the negative of your ungrounded trolling motor batteries. They are there for a reason.

Bruce

[Paul]

Can anybody shed any light on this??

I have never seen circuit protection on both sides of the TM battery(s) rigged from any boat manufacturer or dealer, nore have I ever seen any trolling motor manufacturer recommend protection on both sides of the battery. Surely, if it were needed, wouldn't the TM manufacturers recommend it, and wouldn't the riggers be installing it?

Just curious!

Thanks,

Paul