Battery Cable Butt Connectors

I am planning another electrical system upgrade, including moving the battery switches out of the engine room and up to the living space for better access (safer too). I have seven or eight wires to move about two or three feet up to the new location, however, some of these wires and 0/2 gauge and are already kinda long and secured into some tight places. It would be a TON cheaper and a TON easier to use butt connectors to tack a few more feet onto the end to get the to reach their final destination. Assuming I make properly crimped connections, is there any significant line loss that would have me reconsider?

While I'm not a fan of doing that, I suppose if they make the connectors, it might be ok. IMO, if the cables periodically carry near their load limits, I would be more hesitant to do it.

Have you considered measuring all the cables and the new required lengths to see if you could switch cables around and only have to replace a few of them?

Ted

I am sort of with Ted on this one. Even perfect butt connectors have some voltage drop at the high currents that starter cables carry. And they never stay perfect. Also I guess they are no worse than the ring connectors at the battery switch, although one more connector is one more potential failure point.

But I do recognize the safety advantages of moving the switches out of the engine room. Also I recognize the cost and work involved with going with new, longer cable.

I guess all in all I am ok with it. What does ABYC say? Probably continuous wiring is preferable but no outright prohibition.

David

My concern would be how close to "minimum" sized are the wire runs to begin with.

If wayyy oversized like so many here recommend for every wiring job, might not be an issue at all.

I have had a splice in my windlass run for years with no significant heat or voltage drop issues.....probably because the run is oversized a bit.

Heat issues are also duty cycle dependent. If those cables only ever see close to max load for a few seconds of engine cranking, you won't have heat problems. Sustained heavy load is a different story, however. Voltage drop is a concern in either case.

Personally, that project would be so far down The List it would never make it to the top.
If it did, I'd replace some of the existing switches with remote controlled solenoids like those marketed by Blue Seas for this very purpose. That way no need to do anything with the cables, not to mention the time and hassle involved.

Instead of a butt connector use a bus bar. Psneeld is correct, make sure the guage is adequate for the extra feet.

I agree with caltexflanc.

A solenoid with switch is the best way to do your project. No increase in cable length.

Welding cable would be a lot cheaper

Rather curious how batteries are safer in a living space? Especially when cables would exist in both.

I’d use this with ring terminals to join the wires.
https://www.bluesea.com/products/category/28/3/PowerPost_Connectors/PowerPost

Greetings,
Mr. dd. I think Mr. TB is thinking of relocating the switches NOT the batteries, hence the need to lengthen the cables.

Welding cable is cheaper but will not resist corrosion like tinned.

I just threw out some welding wire that was in my boat and replaced it with proper marine grade cable. I was redoing my battery cables and by taking the longer cables and using them in place of some of the shorter cables, I only needed 2 new cables. I also don’t care for the butt connector but would use a power post in its place.

caltexflanc said:

Personally, that project would be so far down The List it would never make it to the top.
If it did, I'd replace some of the existing switches with remote controlled solenoids like those marketed by Blue Seas for this very purpose. That way no need to do anything with the cables, not to mention the time and hassle involved.

Click to expand...

This would be my first choice.

tiltrider1 said:

Instead of a butt connector use a bus bar. Psneeld is correct, make sure the guage is adequate for the extra feet.

Click to expand...

If that's not feasible, PSN and TR have the right idea....buss bar, not butt splice.

What is the benefit of the power post? It has two crimps same as the butt splice, plus it has a threaded post. Seems like more connections to worry about than the simple butt splice.

And to the safety question above: Moving the switches outside of the engine room makes it easier to shut off the power in case of a fire.

David

RT Firefly said:

Greetings,
Mr. dd. I think Mr. TB is thinking of relocating the switches NOT the batteries, hence the need to lengthen the cables.

Click to expand...

Ah, yes. Missed that one.

Ok, I was in an engine space one time, where the starter motor stuck On. Glad I was close to the batt switch. Of course, the counter argument on batt switch location can be made as well.

diver dave said:

Ah, yes. Missed that one.

Ok, I was in an engine space one time, where the starter motor stuck On. Glad I was close to the batt switch. Of course, the counter argument on batt switch location can be made as well.

Click to expand...

It looks like the Blue Sea remote switch can be controlled manually at the switch as well.

solenoids sound good too...


however I would butt splice in most cases if just lengthening the cable.


power post if it was convenient for something else or other reason.

Although pulling new cables would be the best solution, I certainly understand the hassle that can entail.


I also agree that a butt connection is preferable to a bus bar or post for the reasons DaveM raised.


And it looks like heavy duty but crimp connectors are available is big wire sizes.


https://crimpsupply.com/connectors/2-0-ga-heavy-duty-butt-splice-terminals.html


Just be sure to use a proper crimper with dies for each gauge. Not one of the hammer crimpers, or pliers, or a vise. And get the best shrink tubing you can find.

Of course the best connection is always point to point, but the correct connector *properly* crimped and insulated will be reliable and should add very very little resistance.


I have added a link to some very high quality battery cable connectors.


https://www.delcity.net/store/Copper-Compression-Splices/p_1010.h_89735


Ken

Butt connectors should be fine. Personally better than the power post with now three connections plus the crimps.

Enough comments already about Vdrop and high continuous loads. If you don't have that then the butts should be fine.

Use good quality industrial electrical butt connectors. I see DelCity seems to offer those but any decent electrical wholesaler/distributor should have or be able to get them quickly. Industrial are heavier that the typical automotive type connectors which is so much of the offerings on the marine market.

The industrial ones have thicker walls, better plating, and the wire lead in is a countersink, not a flare. They also provide enough length for a double crimp.

Use a good crimper. If i remember correctly you have an FTZ unit which is good.

Spray the crimps with a corrosion preventative. Just wipe the insulation cover to remove overspray so the tape and the heat shrink will adhere and seal.

I would double heat shrink with the outer layer longer, and then wrap with self sealing 3M Scotch 130C rubber splicing tape with another overlap wrap of 3M electrical tape, not cheap crap tapes.

This will all fuse into a cover that will need to be cut off if access is ever needed. It will not pull apart. Secure the connections and you should have a good, long term connection.

I did a similar project. All my DC wiring led to buss bars located on the battery terminals. I wanted to install proper switches and move all buss bars to the bulkhead in my engine room. So some cables had to be extended. Not more than a couple of feet. Used heavy duty butt splices from Pacer Marine in FL. Link is here:

https://www.pacergroup.net/seamless-tinned-butt-splice/

Obviously putting in new wire would be optimal but given the cost and labor involved I think the butt splices make good sense. And just one person's experience but I've had no trouble.

I should have mentioned the names of the Mfgr.
Thomas & Betts

Burndy
Are two high quality mfgrs of lugs I used.

Thank yall!

I have both the tool and knowledge to do a proper splice.

I thought about buss bars and ring connectors, but also I though that it adds even more connections and failure points. Plus, real estate is an issue. I MAY do a couple of them that way though... probably the lines from the three battery boxes that will allow added fusing and a service point.

Are there solenoid 1/2/off/both switches? I was assuming not. Moreover, that extra expense is something that I am obviously trying to avoid. Adding those... I might as well buy cable. The distance to add is pretty short. In the pictures, the space to move it to is only just a foot above where the bars and switches are now. I won’t be adding more than that.

The loads will minimal. While I have plans to add an inverter, we only plan to use it for minimal duty. So it won’t be pushing the amperage to the ragged edge.

Thanks again for the replies!

As a professional marine electrician I would not butt splice anything bigger than AWG 8; I would use ring terminals and a power post.

In your particular case the Blue Sea Remote Battery Switch is absolutely the best option. I have used as many as 18 of these on a 62' catamaran.

Marine Wiring, Boat Cable and Electrical Genuinedealz.com for all things marine cable.Custom cables made to order and parts in Brunswick, Ga. Really nice mom and pop shop who take pride in their biz. Internet sales make up the bulk of their biz.

CharlieJ said:

As a professional marine electrician I would not butt splice anything bigger than AWG 8; I would use ring terminals and a power post.

Click to expand...

Can you explain why?

CharlieJ said:

As a professional marine electrician I would not butt splice anything bigger than AWG 8; I would use ring terminals and a power post.

In your particular case the Blue Sea Remote Battery Switch is absolutely the best option. I have used as many as 18 of these on a 62' catamaran.

Click to expand...

Why are crimps on Ring terminals/power post any better than a butt splice?

Boy, I’d feel good with double crimped T&B butts, buried in thick wall adhesive lined heat shrink.
Saying that, I have seen the aftermath of 13kV overhead splice that let go. On a sidewalk, a couple inches deep craters turned to glass. Anyway, the more vibration a joint is subjected to, the more one needs to consider how to mechanically stabilize it. A post will do that, but I submit a good heatshrink job will also.