Sealing battery cables after construction....Fear and Loathing in FG land..


Watching you from a ridge
Well, I'm retrofitting a dual battery box to the FG right now.

It's a comprehensive factory kit - box, cables, fasteners, zip ties, Japanese lunch wrappers

I pulled the + battery lead out, the one that goes to the starter. Guess what? Just a standard crimp on lug for both cable ends. No sealant. No nothing. Same for neg lead. Same for accessory leads, for that matter. Thanks for nothing, FUSO.

So has anyone found a decent sealant that actually works for years? Something that'll seal those cable ends? I've used silicone in the past, eventually it failed. Vaseline, dielectric grease...not good enough. Spray on sealants seem to degrade after a while.

If it comes down to it, I'll rebuild the frikkin' cables with marine grade sealant shrink tube...but if there's something out there that will do the same job without having to build new cables, I'd sure like to hear about it.



Also, the GOOD glue lined cable heat shrink should be large enough to fit over the lugs after installed.
The good stuff shrinks a LOT.

Meaning you should be able to slip it over your already made cables.


Ancor Adhesive Lined Shrink Tubing

Hello Czechsix:

We use Ancor Adhesive Lined Heat Shrink Tubing ( Unfortunately, if your cables aren't "tinned" then they may already have started corrosion (that nice green mold look). If you seal the crimps and corrosion has already started you'll slow it down, but not stop it. Tinned battery cables are really expensive - the 4/0 stuff we used to parallel two 200 ah batteries in our sailboat cost $7 a foot twenty years ago! In regular (non-marine) applications I've used new welding wire with ancor crimps (we bought an ancor crimper that works really well), ancor adhesive lined heat shrink tubing to seal the crimps and we've not had any visible corrosion as long as we do everything new.

There is a reasonable debate about proper crimping versus soldering, versus crimping & soldering. If the system has any vibration then proper crimping can allow a minute amount of flex that may prolong the life of the junction over the rigid inflexible soldered joint. The key is a proper crimp that surrounds the lug and squeezes the wire strands and lug into a fused mass. The crimper we bought looks like a bolt cutter on steroids.

You've probably already encountered this, but most modern vehicles have undersized wiring. I suspect this comes from the assumption that the stock vehicle systems will be operating with the engine running and the alternator putting out 13.5 to 14+ volts. When we incorporate that wiring into a system powered by house batteries without charging input our voltages can be 11.9 to 12.5 volts (or lower). That's a reduction of 10 to 15% which increases the resistance and drops the voltage further. I usually use wire gauges designed for a 3% or less drop at the maximum current / distance likely for the particular run. Remember that the distance is the total circuit distance - positive lead run plus negative run (all the way back to the battery).

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Expedition Leader
I oil mine. Spray lube like Break Free or Triflow will keep those connection free of corrosion and keep the coper wire shiny for years. I spray some right on the bare wire so it will wick under the insulation.


If you don't have the crimpers and want to order high quality ready made cables, you can use enter custom cable in the search box. You can then specify the cable size, type, end, length, and opposite end. The lug cables will be professionally sealed, with the high quality shrink wrap.

You can order the heavy duty Ancor adhesive shrink wrap on amazon if it is more convenient. That's what most professionally done ones are done with.

It's large enough to fit after the end is on the cable if you get the right size.


Watching you from a ridge
Thanks for everyone's input.

I'll go ahead and use the shrink tube...just was looking for another avenue, but I guess nothing else has really turned up.


I agree glue-lined shrink tubing is a good bet.

If it were mine, I'd just solder them (or solder up a new cable if needed). Yes there does seem to be a debate out there over crimping vs. soldering, however in 35 years I have never once had a properly soldered connection fail where I've had NUMEROUS crimped ones develop resistance and/or an intermittent in the connection, eventually leading to it burning and/or creating other issues (many of them have been factory-crimped stuff too, so poor crimping jobs isn't the issue). I always make sure the wire or cable is secured in such a way so that it's not flopping around or flexing with vibration... Never had an issue (it's good practice to not leave your wires flopping around regardless of whether you solder or crimp them).


If you are building it all from scratch, i echo the need to use tinned wire, and adhesive heat shrink. You can get it all at greg's marine. its a great outfit and we used them on both of our builds. Then you don't have to worry so much about corrosion and later failure. We crimp and heat shrinked everything and haven't had a failure.

If you need a big crimper for cables, this is one we like.


Kodiak Wrangler
Speaking of crimpers, I picked up one of these 10 Ton Hydraulic Electric Wire Crimpers (with 9 dies) when they were $45 with free shipping (now $55 w/ free shipping). They work well and should last at least one Fuso build.
Largest die is 2/0 so that might be a limitation if you are running huge cables.


SAR guy
Speaking of crimpers, I picked up one of these 10 Ton Hydraulic Electric Wire Crimpers (with 9 dies) when they were $45 with free shipping (now $55 w/ free shipping). They work well and should last at least one Fuso build.
Largest die is 2/0 so that might be a limitation if you are running huge cables.
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I have the Harbor Freight version of these. You might need to grind out the dies for a couple of the sizes, as they are too small for the gauge printed on them. Perhaps the ones in the Yellow box are more accurate. They put an amazing amount of force on your lugs however, and they're also great for swaging steel cables.

My only issue with soldering is that the fine inner wires of a welding cable tend to wick a lot of solder in by capillary action, resulting in the first few inches of the cable becoming stiff.

Also, another vote for glue-lined heatshrink. It's the only way to go.



Expedition Leader
partial solution to the wicking issue is chill the wire and / or use a higher wattage solder gun. You'll get the end done before much of the wire heats up. Helps too if the solder tip is as hot as possible before you make contact with the wire. Heat the wire for the minimum time possible.