View Full Version : DIY waterproof DC power connections

10-22-2014, 11:58 PM
Nerding out and sharing my method using the cheap waterproof (IP68) Adafruit DC connectors... (http://www.adafruit.com/products/743). I don't pretend that this is proper electric for anything but a kayak or in my case, roll-up inflatable, but the basic technique has been working well and on my kaboat everything is always somewhere between wet and underwater... I use these type connectors to run all my electrical to a 12v battery in a dry box. Hacking these connectors is a bit labor intensive but I have discovered nothing sucks on a boat like failing electrical, and for kayaks and roll-ups there are added challenges since the stuff has be portable and is usually drenched.


Materials are glue (Aquaseal is very good but expensive and messy/slow to work with, Stik-N-Seal is much easier but nowhere near as tough), heat shrink, the little Adafruit DC connectors, 18 gauge 2 strand weather resistant cable. 5200 I have used also but it takes forever and needs air to cure so heat shrinking before full cure is a bad idea. I've also used liquid epoxies for some parts but those have no flexibility whatsoever so I like that for sealing actual components...


Cut the Adafruit connector off close to the connector and strip the wires. Strip the cable wires and remember to put the first layer of heat shrink on (if you forget you'll have to use electrical tape after you solder it).


Twist the wires together, and then solder them. This is partly a mechanical connection so use plenty of solder and do a good job. I don't like to use butt connectors because they don't seem to hold as well as a good solder joint.


Snip the protruding lump of solder/twisted wire with diagonal cutters to leave a streamlined solder joint.


Heat shrink or tape the bare wires to keep them from shorting.


Cover every conceivable leak point with your glue. I'm using Aquaseal with Cotol240 so that I don't have to wait 12 hours to finish this thing. Stik-N-Seal is my other go-to but this particular cable may see particularly hard use and I trust Aquaseal more.


Slip heat shrink over the wet glue and position it. With these connectors I like to run the heat shrink up past the wire and onto the connector. Now you have to wait until your glue is at the very least tacky but not sticky. For Stik-N-Seal about 20 mins, Aquaseal may take several hours, and Aquaseal with Cotol240 about 40 mins.

I have also taped the Adafruit screw down connector to the tip so it doesn't slip into the glue and make a mess.


Heat shrink the joint. Remember most of these glues contain flammable solvents, and if you rush and try to heat shrink before the glue is dry enough you will at the very least have hot bubbling noxious glue oozing out of the ends of the heatshrink (messy but more or less okay from a waterproofing standpoint), or even splitting your heat shrink and boiling out and catching fire, etc.

10-25-2015, 09:46 PM
Just thought I'd revist this thread... The Adafruit connectors have held up to depth on various devices (about 80' so far), but the main weakness has been vibration on my inflatable. The battery system is in the bow, so it gets slammed around really hard and for non-electronic devices (such as my steering) they have been okay, but for electronics like the fishfinder, a split second interrupt in power means the thing turns itself off.

Also the 'solder, aquaseal, heatshrink' works very well, but I am no longer trimming the cables short and heatshrinking onto the DC connector--this seems to exaggerate problems with vibration. Better to leave the cable loose so there is plenty of play.

It is bulkier and more labor intensive but one trick to get around problems with vibration has been bedding cables inside to 1/2" plastic PEX swivel connectors with crimp on quick disconnects inside. Pretty cheap, only a couple bucks per connector, but less convenient since the quick disconnects are harder to work with making it more of a semi-permanent coupling.

For a little more ease of connect/disconnect, but higher cost (looking at about $10 per connect), is putting JAE motorcylce connects inside the PEX tubes...

02-10-2016, 06:13 PM
Update since somebody was asking me for info on building a fuse box...

Getting into more expensive territory since you absolutely need a proper crimping tool ($30 from Amazon) to use the JAE motorcycle connects but in my case it was money well spent...

Been using these fuse boxes on the kaboat all winter. Besides some splashing and some mechanical stress from living on the transom they have been subjected to no real punishment until Sunday. We had some engine trouble and the unit spent about 30 minutes mostly underwater as waves were coming in faster than we could bail, with no electrical problems. Mine are epoxy potted into a 3d printed nylon shell but the clear removal cover is the stock JAE:

The back of the stock fuse box looked like a definite weak point for submersion, not an issue for my build but anyone else looking to use them in a marine environment should probably find a way to seal those openings.


That is the junction box they went in, up there on the upper left. This system is different from the builds I started with where I put batteries and fuses inside a dry box together, current one is more modular with JAE connectors inside PEX, connecting the different components. Battery(s) are separate, and in their own completely diveproof box; very happy with it, held up flawlessly, now if I could say the same for my engine...

The kaboat review on my YouTube channel has more coverage of the unit.