terminal block or connector for ~8 AWG wire in marine environment - Page 1
Forum section: electronics / general

author: JeanF
author_rank: Regular Contributor
timestamp: October 29, 2020, 11:26:54 am
content: Hello,I'm looking for connector / screw terminal recommendations. I came up with something a while back, but I'd like to improve it.I have a 2 conductor cable that I need to lengthen. It's coming from a small (9.9HP) outboard motor, and it's the stock cable that comes with the motor. It's meant to connect to a small battery for the electric start option.I'll have to double check when I can (yay, lockdown again!) but I think it's about 8 AWG or maybe 10 mm². It has very thick rubber insulation, and it's a zip-cord / speaker wire / figure 8 cable style.The starting current is probably not that huge ; the starter has a 20A fuse inline, but I guess the manufacturer wanted to have some headroom.One end of the cable stays attached to the motor. Technically the lugs can be unscrewed under the hood near the starter relay, but there's not much room in there, I'd rather not do that. At least, certainly not on a regular basis ; the threads wouldn't like that either.The cable goes through a hole in the aluminium transom; obviously, the smaller the hole, the better. Currently it's an oval hole just big enough for the cable to go through. Without a grommet, yes, I know, it's bad, but the cable doesn't move much, the edges of the hole are smooth with a little chamfer, and I've not seen any damage on the cable jacket for 5+ years. I'd rather not enlarge the hole, nor drill another one, if I can avoid it. (A)The battery was previously fastened inside a trunk at the rear of the boat. I'd like to move the battery inside the cabin, hence my need to make a connection and lengthen the cable. But the engine is removed from the boat during the winter. So I need a removable connector, not just a butt crimp + heat shrink.(A) means that I have some limitations about the style of connector. Small ring lugs can pass through the hole; bootlace ferrules could as well. The metal part of Anderson connectors could pass as well, but it's a bit of a pain to have to disassemble the connector before being able to pull the cable through the transom...What would you recommend ? The criteria are simplicity, ease of disconnection, robustness, corrosion resistance. I'll be probably enclosing the connection in a small weatherproof junction box.For now, I've considered:- barrier strip (two pole, dual row). Looks good, and can be screwed down to the back of the box, but they tend to be on the small side. Some are rated at 30 A, but most are rated for 14 or 12 AWG maximum. There's not much room for a ring lug except maybe the smaller ones. The screws are a bit too weak, I'd prefer M4 or M5 or M6, preferably stainless.- euro style terminal blocks. I don't like the fact that they use a single screw to push on the wire. Bootlace ferrules can mitigate this, but I think the "rising cage" system would be better. Do "euro style terminal blocks but with rising cage mechanisms" exist ?- making a custom terminal, for example with a piece of HDPE as a base and two stainless screws + large washers + serrated lock washers + nuts, and putting ring lugs on all ends of the two wires. Looks promising, but I'm not sure how to prevent the screws from spinning when tightening the nuts. Otherwise, I could use "bonding studs" (made for composite industry) + standoffs, and pot everything in a small box with the potting compound flush with the standoff. Bonding studs are not easy to find in small quantities, and I can't make my own (I don't have access to TIG welding). Either way, all that could look neat in the end but involves a bit of work, I wonder if there is an off-the-shelf solution.- 4mm banana connectors - that would be an elegant solution, but I'm not sure the nickel plating would survive well in such a corrosive marine environment.- does someone make a kind of Wago 221 lever connectors, but for larger wire ?- of course I could move the connector to the outside, behind the transom. Then, it would be easier to disconnect. But that connector would be directly exposed to saltwater projections and rain, so it would have to be really good. And it would look a bit messy to have a connector hanging here. Without an apparent connector outside, the cable can be tied with the fuel line, and it looks reasonably neat.- ring lugs + short bolts + electrical tape. Works, but ugly... If the two "joints" are kept in a small box, it could be tricky to tighten the screws with two spanners without shorting everything, and tricky to apply tape as well. If I ditch the box and leave the connections flying around, it looks very unprofessional and can get problematic if the tapes falls out and the lugs touch the aluminium hull.As a side note, the boat is not mine. If possible, I'd really like a kind of "show-my-father-how-it-works-and-forget-about-it" solution, rather than having to do it myself twice a yearThank you for any hints or suggestions

author: bill_c
author_rank: Regular Contributor
timestamp: October 29, 2020, 12:01:17 pm
content: Smear Noalox, Penatrox, or similar over the contacts and it might survive. These are common on battery operated forklifts and are available in several sizes.

author: JeanF
author_rank: Regular Contributor
timestamp: October 29, 2020, 12:32:29 pm
content: thank you for the tip about the antioxidant compounds. I think dielectric grease could help as well.Quote from: bill_c on October 29, 2020, 12:01:17 pmThe whole connector would be too big to go through the hole I mentioned, but, by removing the contacts, they could pass one at a time. There is a risk of error when reassembling, but not more than when using screw connections, where terminals could also be swapped.I've used these connectors in the past, with the appropriate rubber boots, and dielectric grease. Water still seeped in and they corroded badly. So I don't have fond memories of them, but they could be an option.Does anyone have other ideas?Edit : strangely enough, your picture shows up on my phone and on Firefox, but not on Chrome

author: nctnico
author_rank: Super Contributor
timestamp: October 30, 2020, 11:49:20 am
content: I'd look for automotive connectors. A lot of these are wire to wire and are waterproof.

author: ChuckDarwin
author_rank: Regular Contributor
timestamp: October 30, 2020, 04:57:47 pm
content: Aside from the SBx/SC series noted above, Anderson makes "powerpole" connectors that are available as interconnecting singles (https://www.andersonpower.com/us/en/ProductPages.html) If you slightly stagger the two connectors on a cable, the cable might fit through your port and also lessen the chance of connecting the wrong terminals together. Stacked side-by-side, they are keyed, like their bigger cousins.Also look at Delphi Weather Pack and Metri Pack (sometimes Metri-Pack) sealed connectors for weather resistant connectors. Metri Pack will carry higher amps than Weather Pack, I believe.edit: spelling

author: bill_c
author_rank: Regular Contributor
timestamp: October 31, 2020, 09:52:02 pm
content: I have been using Noalox (and similar) on all vehicle battery terminals and any outdoor wiring for 30 years, haven't had a single problem with corrosion, and some of these forklifts have been here the whole 30 years with the same terminals. Salt may be a different story though. The dielectric grease doesn't have a corrosion inhibitor so it will not do as well.

author: mzzj
author_rank: Super Contributor
timestamp: October 31, 2020, 10:11:44 pm
content: Quote from: JeanF on October 29, 2020, 11:26:54 amRing lugs, cable with tinned braids(to prevent green rot inside the cable). Slathered with dielectric grease or antioxidant grease.Single "captive bolt" so that you need only one spanner to tighten the connection(s)like thishttps://www.waytekwire.com/item/47202/Junction-Block-Stud-47202-/

author: TerraHertz
author_rank: Super Contributor
timestamp: October 31, 2020, 10:43:00 pm
content: Any suitable in-line, snap-together battery connector, that you can put on the cable along the fuel line, for ease of removing the motor.And then... wrap the connector in denso tape. This is a cloth tape embedded in a kind of dense, non-flowing, weatherproof grease. It's very sticky, forms watertight seals to almost anything, including itself. You wrap it on a few layers thick, squish it down, mold the bulk to a neat shape. It's a water-exclusion bandage.Add some self-bonding rubber tape or shrinkwrap on top, for wear resistance if you like. Or a PVC wrap-around sheath, wiretied.When you need to disconnect, you can unwrap the denso tape for re-use, or cut it off and apply new densotape.

author: JeanF
author_rank: Regular Contributor
timestamp: November 01, 2020, 07:45:50 pm
content: I hadn't thought about automotive connectors, probably because I have no experience with them and I imagine there would be so many of them that I wouldn't even know where to start, but I'll have a look! I didn't know about Delphi connectors either, thanks for the recommendation.I really appreciate the hint about Denso tape, I've never heard of it but it looks very promising indeed! I'm not sure I'll go this way for this project, but for sure I'll keep that in mind in the future. With rubber on top as you say that would be quite a bulletproof solution, but I'm guessing that it would need a little practice (or at least, a minimal amount of dedication) in order to get a waterproof and not-too-ugly result. I'm not sure my dad would bother with all that and I would fear the worst ("... I couldn't find the fancy tape you gave me, I used packing tape, that'll be fine")With that in mind, I think it's better to keep the connection indoors. Tightening a nut over a ring lug and adding a dab of anticorrosion grease would be waaay easier for him...mzzj, thanks to you I've been able to find many variations of the item you linked to. I was missing the keywords "junction block", "junction block stud" and "power post". That's awesome, now I won't have to make one myself! Previously I could only find one model, locally, which was of the bulkhead/passthrough type (not wanted here), as well as too big and a complete ripoff (32 € per piece)amusingly, the term "captive bolt" that you used gave me totally unexpected resultsbut I get the idea. ("captive stud" seems to be a bit better here)Thanks again, everyone