Hot Buss terminals??

[Cutty Sark]

Does anyone have an switched always hot, buss terminal near the battery? I want to clean up the posts on the house battery and I am adding a positive /negative buss right there in the lazarette( along with VSR etc...). I'm trying to decide weather to fuse or breaker the hot side, all the house stuff in the cabin is breakered, but the bilge pumps, wallas and downriggers all like to be hooked straight to the battery. The riggers aren't as important, but the wallas and the 2 bilge pumps are. I can't decide whether to breaker it or not, everything has a fuse right there already, but I just can't decide whether to fuse the buss or not? The buss is covered of course. Any thoughts??

Sark

 

[MOOSE]

I did exactly that last year in order to clean up all the stuff connected directly to the battery. On a piece of Starboard in the starboard lazarette I put in three buss bars (switched, unswitched, and negative) and two small fuse blocks. I made up a cover for the whole mess out of clear Lexan. IMHO this was a job worth doing; it really cleaned things up. I can try to post a pic of my installation if you want, but it sounds like you know what you're doing.
Al

 

[Larry H]

Sark,

The 12 volt positive wires are supposed to be fused within 7 inches of the 12 volt source, except the 12 volt wire to the engine starter. That distance increases to 40 inches if the wire is in a sheath or conduit.

 

[Jazzmanic]

Al,

A picture would be greatly appreciated for those of us who are electronically impaired :lol:

I can try to post a pic of my installation if you want, but it sounds like you know what you're doing.
Al

Peter

 

[MOOSE]

Let me tell you, there ain't no one more electrically challenged than I am. But you are in luck as we are in the midst of a minor heat wave so I'll crawl in tomorrow and see if I can immortalize my work in a pic. Stay tuned.
Al

 

[AstoriaDave]

The 12 volt positive wires are supposed to be fused within 7 inches of the 12 volt source, except the 12 volt wire to the engine starter. That distance increases to 40 inches if the wire is in a sheath or conduit.

These are the rules I followed in wiring up my homebuilt boat. BlueSea sells some low-profile fuse blocks that are designed for high-amperage circuits. Easy to fit close to the battery. If you fuse the line to the +12 buss blocks, you're covered, with much less stuff than fusing each circuit as it leaves the buss.

Here is a link to a photo of that installation; in my case, the supply wire for a 40A service exits a battery box through a piece of 3/8ths ply, and then to the fuse: http://www.pbase.com/bartenderdave/imag ... 0/original

Split loom is an easy way to get "sheathing" in place. I also put in a 30A breaker for this circuit, up near the stuff it serves, in a handy spot, so that if something goes haywire, I can just dose out the problem and reset the breaker. The 40A fuse is harder to get to, and is there just to protect the supply wire.

Hope this helps.

 

[journey on]

I think that installing a positive buss next to the battery is a great idea, and something I want to do (soon.) Now, about fusing.

I've wondered about fusing between the battery and the positive buss. This essentially protects the wire between the fuse and the buss, since all the different circuits branch out from the buss. This would have to be sized to the maximum total load out of the battery (~100 amp fuse,) since that is what the output of the battery can handle.

It would make more sense to fuse the individual circuits as they leave the buss bar, since one could then install fuses sized to each circuit. The wire out of the battery has a VERY low probability of shorting.

Of course, since any fuses at the buss bar would only protect the wiring circuit, one would have to go downstream of each fuse to make certain that each piece of equipment is fused as well.

The truck does have a fuseable link coming out of the battery, and must have over 100 fuses scattered around the place. And it's a bottom of the line truck, so there's not much optional equipment. I've had one circuit blow, and spent days finding out which fuse is the right one. The local dealer was willing to tell me for $90.

The C-Dory factory supplies fuses to specific equipment connected directly to the battery (the Wallis has it's own fuse, for example) and also fuses each circuit at the DC panel. This seems adequate to me. That's a balance between over and under fusing, and probably meets boat builder requirements.

Boris

 

[MOOSE]

Ok, here's a picture of the buss bars and fuse blocks I installed in the starboard lazarette. It made some order out of the chaos of too many leads directly from the battery. I don't like in-line fuses; these are all in one spot. I made a diagram so that I can easily tell which fuse is for which piece of equipment.

Al

 

[Captains Cat]

I guess you can't have too many fuses :shock: but sometimes it seems overkill. Unless the fuse or ckt breaker is on the positive terminal, there's always a chance of a short between the last protection and the terminal. Then there's the problem of finding out which one blew if there's more than one in a circuit....

Charlie

 

[Cutty Sark]

Well, I've got most of the added components on this project mounted and have decided to go ahead and use an 80 amp fuse between the buss and switch. I still dont get the fuse within seven inches of the battery though. If you have a battery switch which most of us do, the cable from the battery to the switch is usually more than 7 inches in itself. And all the ones they sell are at least 2-1/2 times that length. So do you have to make your own battery cables? Those crimpers for the 2 or 4 AWG cable aren't cheap for the one application. Also when I received my boat from Cdory the main breaker for the DC was down current from the switch and well over 7 inches from the battery( more like 20) but it is mostly in the white sheathing, so if it's sheathed you can break this rule? Anyway I'm mostly on track now although still a couple questions, the main one being a fuse between the house battery and the VSR, BEP marine has that labeled as optional? I will take some pics of my installation as it progresses too. Has definitly been a learning experience.

Sark

 

[AstoriaDave]

Well, I've got most of the added components on this project mounted and have decided to go ahead and use an 80 amp fuse between the buss and switch. I still dont get the fuse within seven inches of the battery though. [snip] Also when I received my boat from Cdory the main breaker for the DC was down current from the switch and well over 7 inches from the battery( more like 20) but it is mostly in the white sheathing, so if it's sheathed you can break this rule?

Sark, I went through the same thrash you are going through. I had to start measuring my "seven inches" after the battery switch, also (see photo link in previous post). I think the "rules" say 40 inches to the overcurrent protection (breaker or fuse) if the cable is sheathed. I think the bottom line here is to minimize the exposure to a dead short in the unprotected portion of the supply line (+12 V), and you may have to shake and bake a little. The guy I share my boat storage area with is a former USCG marine safety officer (recently retired), and he told me those rules are there as guidelines, and he had signed off on several installations (in commercial vessels) which deviated.

Like you, I could not follow all the "rules" to the letter, so I did the best I could. I slit some fuel hose and used that as "sheathing" on the supply line to the starter (not required by the rules), and in a couple other places I used some split loom. In the battery box, I cable-tied the split loom onto the positive and negative cables, and ran it over the bare terminal hardware and cable-tied, that also. I have to clip those when accessing the battery terminals, but they are cheap and easy to replace.

The chance of a catastrophic meltdown is darn small if you do stuff like that, and mostly it is not difficult. I wired all of my boat (it is a simple setup -- only one battery, only 12 VDC; no 110AC wiring), and really learned to appreciate split loom. I got a bunch from Radio Shack, and some from the local marine supply outfit (Englund Marine).

Sounds like you are doing a fine job.

 

[Sea Wolf]

SARK-

Crimping custom battery cables can be done a number of ways.

The most inexpensive tool is a hammer driven die and punch set up that looks like this:

Much more expensive is the battery lug crimping tool that looks like this:

or this:

However, you can use (at least I do) wire crimping tools used for stainless shrouds and halyards on sailboats at look like this:

or this in the bench mounted style:

Now here's the deal.

The later two types of cable crimpers will work for at least some sizes of battery cable. I have a pair of the next to the last type and they work fine on 6 gauge battery cable.

The bench type is available for free use when making up your own wire rigging at West Marine stores, maybe other dealers. I wouldn't be afraid to take my battery cable stock and lugs into a WM store and take a look to see if the size of one of the dies in their crimper wasn't pretty close to what's needed.

The lugs and copper cables are very soft compared to stainless wire and NicoPress collars (sleeves), and a simple test run will quickly tell you whether you can compress the lugs on the bare battery cable wires. You can tell very easily whether the pressure you have to apply on the lever arm is excessive, and if in doubt, get one of the guys in the store to help you because he will know how much the tool can take.

Maybe you know some sailor with one of the tools above?

Anyway, this is an easy out of the high cost one time tool use dilemma.

Oh, and by the way, the standards allow a longer length for a shielded cable as compared to a non-shielded one simply because of the extra protection.

Someone earlier here this year ran the battery cable in a PVC pipe forward through the cockpit and cabin. Personally, I'd think a 2 gauge cable in a 1/2" schedule 40 PVC pipe that was secured down with straps would be very hard to short out! This plastic split loom wire bundlers, on the other hand, are almost more cosmetic than truly functional as insulators (IMHO)!

Good Luck!

Joe. :thup :teeth

 

[AstoriaDave]

Adding onto Joe's suggestions about crimping larger cables: I took mine down to the marine supply store and had them use their fancy crimpers, after I had determined from a test fit what length of cable and what terminations I needed. Don't know if all marine supply stores will do this, but the one here in Astoria will.

 

[thataway]

Although I use rachet crimpers for the sizes 10 on up, I use the cheaper but effective crimper such as: Ancor 701010 heavy duty crimper ($82 at West marine, but much cheaper at other outlets). I then fill the bottom of the crimp with solder, heating the fitting with a torch, and then cover the top of the crimp and cable with adhesive shrink wrap. This technique has served me well for many years, and I have never had the probelm with corrosion around heavy cables.

Avoid buying premade cables from auto supply stores. The wire is not tinned and occasionally fittings are subject to corrosion or rust.

One CAUTION, that is to be sure and put a shield over all of these bus bars which are in any place. This holds for lazarettes or the console etc. These plastic covers are available for all bus bars. If you do not, this is a violation of ABYC standards.

Also consider putting a corrosion blocker over these bus bars on a regular basis, since they are subject to spray or salt air.

 

[CAVU]

My makeshift wire crimper. I used this setup to make a short jumper cable which needed to be just the right length. I used 3/8 in square bar stock. Clamp together and center drill in a drill press. Use a bit just a little smaller than the crimp. I experimented a little to get just the right size. Clamp tight in a bench vise. Hey I'm cheap.

 

[Sea Wolf]

My makeshift wire crimper. I used this setup to make a short jumper cable which needed to be just the right length. I used 3/8 in square bar stock. Clamp together and center drill in a drill press. Use a bit just a little smaller than the crimp. I experimented a little to get just the right size. Clamp tight in a bench vise. Hey I'm cheap.

Hey Ken!

I'm with you, especially on the cheap part!

Your tool looks like an inexpensive Nicopress swaging tool made to allow swaging of stainless cables on small sailboats:

Good idea!:idea

See Ya' in Seattle!

Joe. :thup :teeth

 

[mikeporterinmd]

Ancor makes a nice little lug press that you hit with a hammer in order
to crimp the lugs. Works from 6 on down to something large...

I went with the Blue Seas fuse box busses. The main buss can handle
up to 120 amps, I think. Each circuit coming off is fused. I have two
in the lazarette, one for house power and one that comes off the starting
battery, prior to the switch. This where I run the bildge pump from.

I have never figured out how to fuse the cables from the batteries to
the switch. I have very short (about 7") from the switches to the above
mentioned fuse blocks.

So, if a battery cable shorts, I have big problems. But, everything else
is protected. Does anyone make a good inline breaker so I could
have protection on the battery cables? What amperate should they
trip at? What current does the starter for a 90hp Honda use?

Mike

 

[Plan C]

A good crimp is probably adequate, but you can easily solder as well. I use a small Ronstan torch (WalMart) to heat the fitting and wire so the solder gets sucked in. That will fill some spaces.

Dave

 

[CAVU]

Everything I have read would indicate that all the connections should be crimped and not soldered? I think the reasoning is if the wire heats up it could melt the low temperature solder from the connection and cause arcing. I can't remember where I read this. Anyone know if there is a "rule" on this?

 

[Larry H]

Mike,

A fuse or breaker is NOT required on the battery cable to the starter motor. If you are concerned about a short, you could run that wire inside a sheath. As far as I know, no motor manufacturer uses a fuse in the battery cable from the starter motor to the battery. The current load is very large when the starter operates.

To see what that current can be, check your motor's owners manual for the cranking amps required from the battery. Marine batteries are rated for 'MCA' (marine cranking amps), that is amps available at 32 degrees F. Auto batteries are rated for 'CCA' (cold cranking amps), which is amps available at 0 degrees F.

Any fuse in the starter circuit would have to be large and expensive and if it failed, you might not be able to start your motor in an emergency.