Fuses needed or not?

[gm280]

Re: Fuses needed or not?

I don't think its a good idea to put a fuse in the cable that goes to the starter. Too many safety issue if the fuse happens to blow, loosen up, corrode...especially if you happen to be in a dicey situation and you need the engine started NOW.

They are not required for a reason!

bruce, I do understand what you are saying and for good reasons too. But you may be surprised to know that lots of vehicles do have inline fusible links built into the positive lead coming for the battery. Its there and viewing the vehicle schematic you will see it listed also. So it is not that unusual... And it is not a low amperage fusible link either and for good reason! Not a lot of folks know that that fusible link is there from the factory...

 

[bruceb58]

Re: Fuses needed or not?

So it is not that unusual... And it is not a low amperage fusible link either and for good reason! Not a lot of folks know that that fusible link is there from the factory...

Please show a boat schematic that has one between the starter and the battery....you won't. From the starter to the main harness you will have one if there is no breaker. My OMC Cobra had the fusible link. My Volvo has the breaker.

 

[sam am I]

Re: Fuses needed or not?

I could show you hundreds or, just ask anyone here that's been in/on a Sub and/or in the Navy!!!........If anyone requires safety and reliability leading to a main high current electric motor/s from batteries(100's) at 1000's of amps, 100's of feet underwater with battery gases in confined spaces and ultra critical fire safety needs, I'd think our Navy would be a fair testament eh?.......

Fusing/breakering batteries to high current/torque motors is done, it is safe and reliable, been there, done that!!

It's cost verses convenience people, consumers wouldn't pay for it, it can be bulky, expensive and might require some maintenance, therefor not many(if any) consumer manu's have even wasted their time.....The technology is there, has been there and has been done quite a long time, just not in play school boats we buy and use as consumers.

This post has drifted off too far, too many experts here..........again!!

OP, you're good to go with what you have on your schematic as what is "recommended", don't sweat the "what isn't" or "what could be's" but, you certainly could fuse/breaker it and it works, else I'd be in BIG trouble!! Caveat.....if done properly.

And of course, JMO.

 

[bruceb58]

Re: Fuses needed or not?

According to post #5 you said no fuses was best practice. I am agreeing with that statement. It also follows ABYC standards.

 

[sam am I]

Re: Fuses needed or not?

Yup, for the average consumer, having them designing systems like this might not be so good. Better stick with what is available/recommended to them.......agreed, best practice to not.

My mistake if I misread something......I need coffee and this has got twisted too much....I'm gone.

 

[gm280]

Re: Fuses needed or not?

I could show you hundreds or, just ask anyone here that's been in/on a Sub and/or in the Navy!!!........If anyone requires safety and reliability leading to a main high current electric motor/s from batteries(100's) at 1000's of amps, 100's of feet underwater with battery gases in confined spaces and ultra critical fire safety needs, I'd think our Navy would be a fair testament eh?.......

Fusing/breakering batteries to high current/torque motors is done, it is safe and reliable, been there, done that!!

It's cost verses convenience people, consumers wouldn't pay for it, it can be bulky, expensive and might require some maintenance, therefor not many(if any) consumer manu's have even wasted their time.....The technology is there, has been there and has been done quite a long time, just not in play school boats we buy and use as consumers.

This post has drifted off too far, too many experts here..........again!!

OP, you're good to go with what you have on your schematic as what is "recommended", don't sweat the "what isn't" or "what could be's" but, you certainly could fuse/breaker it and it works, else I'd be in BIG trouble!! Caveat.....if done properly.

And of course, JMO.

.

I don't think we drifted off from the OP question at all. In fact I think we covered his questions very well. With all the info provided, it is up to his interpretation whether he wants to install fuses, circuit breakers or nothing. That IS what these comment boards are supposed to do. Inform the OP of his/her options. I think we covered them quite well. He has to make up his mind for his boating issues. The fact that most don't install any protection is a valid point... I probably will for my own piece of mind though.

And if everybody had the exact same opinions, there would be no need for any iboat question and possible answer comment board...

 

[sam am I]

Re: Fuses needed or not?

Well he asked if he "needed fuses downstream of the batteries before the switch" to which we said "no, not required/recommended" follow best practice, then it went south?.............all good info but, certainly south of what he asked for.

I'm guilty as charged and will stay out fishing an extra 4 hours as punishment......

 

[Auger01]

Re: Fuses needed or not?

BoatUS did a study of why boats catch fire. They found that over half of the fires were started by electrical issues. With the current trend of installing multiple batteries and/or more electrioncs, I think that this percentage will likely only increase.

BoatUS: Seaworthy

 

[UncleWillie]

Re: Fuses needed or not?

Please show a boat schematic that has one between the starter and the battery....you won't. From the starter to the main harness you will have one if there is no breaker...

I could show you hundreds or, just ask anyone here that's been in/on a Sub and/or in the Navy!!!........If anyone requires safety and reliability leading to a main high current electric motor/s from batteries(100's) at 1000's of amps, 100's of feet underwater with battery gases in confined spaces and ultra critical fire safety needs, I'd think our Navy would be a fair testament eh?...
Fusing/breakering batteries to high current/torque motors is done, it is safe and reliable, been there, done that!! ...

The question is about Fusing the wire from the Battery to the Starter, not between the Battery and any electrical motors that may be on board. Trolling motors, Yes! Submarine main electrical motors, Yes! Starter motors No!
It is highly likely that the batteries to the Starting Motors on any Diesel Generators on the Subs were Not fused.

The fundamental difference is that the Submarine and the Trolling Motors are wired with cable that can handle the nominal currents Continuously.
The starter circuit typically is wired with cable that WILL smoke if the current normally handled by it were to continue for as little as a minute.
Starter wiring sees a momentary spike approaching 1000 amps followed by a couple of seconds in the few hundred amp range... But the wiring is typically rated for Less Than 100 amps continuously.

This is a different situation from where the Batteries continuously supply 1000 amps to a motor through wiring that could handle 3000 amps continuously with a 2000 amp fuse in line.

 

[sam am I]

Re: Fuses needed or not?

Agreed U.W., if under sized for continues.....to which they weren't. And yes, in our boats, yes, they typically are or very very close otherwise as I eluded too and still stand by my comments in #17.....As I said, "my mistake if I misread something" with fusing electric motors otherwise, I will fish 4 hrs extra for punishment and will assuredly make many many more misread's again as spring nears to fish even more and not be here wasting fishing time!!!

 

[The Revenge]

Re: Fuses needed or not?

Ok I was about to fuse wires to outboard. Now I won't. If I was going to what would be a good fuse to use? One that sits on the battery terminal with a clear box? What amp fuse?

On a side note tell me what you guys think.
I ran an 8 gauge wire from my battery selector common post to a fuse/ circuit breaker device, 30amp and resettable. That wire is 6" long.
Then after the breaker I continued with 8 gauge to the blue sea 12 post fuse box. That wire is 14" long.
The ground wire to the fuse box is also 8 gauge.
All that sound okay?

My main battery wires are 2 gauge.

Thanks for all the info. Learning new stuff here.

 

[Auger01]

Re: Fuses needed or not?

8ga wire and 30 amp fuse is good. 10 guage would even work for 30 amps. The length after the c.b. is not critical unless it gets super long.

2ga wire is probably ok, but would need to know length and engine type to say for certian.

 

[The Revenge]

Re: Fuses needed or not?

Ok here we go. I did make one or two changes to this but that's it.
I moved the little breaker device up to the left of and next to the battery selector. That way the main battery wires have a more clear shot to the battery selector. I ran an 8 gauge wire from the negative battery terminal to the post on the right side to supply the ground.
This is mounted on starboard. I'm mounting this upside down inside my mahogany console.
Only thing left to do is run the wires from the fuse panel to gps, radio, I'm using 16 gauge for that.
Also two accessory/cig lighter device wires. Using 12 gauge for those.
Then one 12 gauge wire from the fuse box to a Hella six switch panel on dash. That will run bilge pump, curt lights and nav lights.
Motor is a 90 etec and the run from the console is 12 ft. I used 2 ga.
Is 16 gauge enough for GPS/chart plotter, radio, bilge pump, lights?
My battery is a die hard platinum AGM, group 34. 68 amp hour, 880 CCA, 135 RC.
Thanks a ton.

 

[Auger01]

Re: Fuses needed or not?

You should run individual wires from the fuse block to each switch.

16 ga might be marginal for the radio and bilge. Here is a good reference:

http://assets.bluesea.com/files/resources/reference/20010.pdf

2 ga is good for the 90.

 

[bruceb58]

Re: Fuses needed or not?

Looks fine.

2 gauge is plenty. I have a 90 Merc Outboard and I am running 4 ga to the switch. The original cables to the engine were 6.

 

[UncleWillie]

Re: Fuses needed or not?

... Motor is a 90 etec and the run from the console is 12 ft. I used 2 ga. ...

What is the 12 foot of 2 AWG from the Console to the motor for?
Not the Starter!

 

[The Revenge]

Re: Fuses needed or not?

Yes. 2 gauge from battery selector to engine starter. Might be a foot or two less. It's not hooked up yet, it's sitting on the deck at the stern. The motors not on yet.
I read that the Etec installation guide only recommends 4 gauge up to 10'. Then they want you to increase size of wire.
Not good?

 

[bruceb58]

Re: Fuses needed or not?

I missed that. I would have the battery near the motor and the selector back there. If you are actually running it that far then maybe you do need a fuse.

 

[sam am I]

Re: Fuses needed or not?

Lol.....I don't think he said that till now:faint2:


2 AWG, 181 amps max, drops approx. 0.578VDC @ 150 amps(4 cylinder 90HP) @ 12' * 2 = 1.156VDC.....hmmmm.

Where is the battery boxes? If they're at the back of the boat(or can fit at back), you should keep the selector switch at back along with cranking batts as U.W. and Bruce picked up on. Dropping over a volt on both positive and return wires, (or common and a batt 1/2 wire if just running a selector switch forward) will have a bit of negative effect on crank speed of the starter. Not too worried about a fuse, although do'able

 

[The Revenge]

Re: Fuses needed or not?

I didn't realize it would be that great of a drop. That's why I used 2ga instead of 4ga.
I'll get proper measurements tomorrow. What's the next size up 1 gauge?