Soldering battery lugs

Arminius

Arminius

Well-Known Member
Oct 30, 2019
1,061
Seattle
Boat Info
Bowrider 200 Select, 2003
Engines
5.0L MPI, 260 hp w/Alpha 1 Drive
My high wattage gun was not doing the job with #6. Instant success with the Mapp gas torch. Put the lug (or Anderson connector) just barely in the vise with the flux coated socket pointing up, inserted the cable, hit the lug just above the jaws with the flame and inserted 50/50 solder wire. Requires 3 hands but that solder was melted and the wire potted before the insulation could melt back. Nice to be confident it will never pull out.
 
Arminius said:
My high wattage gun was not doing the job with #6. Instant success with the Mapp gas torch. Put the lug (or Anderson connector) just barely in the vise with the flux coated socket pointing up, inserted the cable, hit the lug just above the jaws with the flame and inserted 50/50 solder wire. Requires 3 hands but that solder was melted and the wire potted before the insulation could melt back. Nice to be confident it will never pull out.
Click to expand...

Crimping is definitely the recommended method here and because of the wire size you may need a hydraulic or hammered crimp.

-Kevin
 
You guys are too funny.... it’s a bit intimidating to post something technical on this forum...


 
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scoflaw said:
What some don't understand is that if there was an over amp situation the solder would melt and the connection would pop loose.
Click to expand...
Good point.... although I think of a lot of other bad things already happened... but no harm in crimping
 
You can buy a hydraulic crimp tool with all the dies for $50 on Amazon. Buy tinned copper lugs and you have everything you need to make great power leads.
 
I went up to Pacific Battery central in Everett, WA to have my winch #8 cable made up, clamps on one end, Anderson on the other. They screwed up both ends with their crimper!!!
The out of round crimp would no longer slide into the Anderson plug and had to be ground round. The clamps were intended to be soldered and they came up with a wrap around crimp that broke one of the copper tabs. "Lead is bad for you and therefor illegal" may have hindered them.
My point is I got a nice flood practically just touching the lug with the hot Mapp gas flame. I did pre-silver the wire before fitting it into the resin flux anointed socket and heating. The result sure is pretty!!
Many house fires are started by resistance corrosion at a poor mechanical connection whose resistance produces heat and a special corrosion sets in increasing corrosion and increasing heat until the house burns down. A fire marshal showed me an example after a total loss.
The marine environment could not help but worsen this process.
There is no evidence after a marina or boat burns cause the whole thing sinks!
 
scoflaw said:
"just touching the lug with the Mapp gas flame" gives you the idea how low the melting point of solder is.
Click to expand...
Agreed 100%. Crimp and then solder if you think it will help, but I would never use solder alone on a boat main battery. Any corrosion between the post and the lug will generate heat and the solder can easily melt and the wire pull out of the lug. If it was crimped, it will hold even if the solder melts.
 
The lowest melting point of solder (50/50) is 183C (361F). If your battery terminals are getting even close to that - you have other issues.

I do agree that you should have a mechanical and electrical connection - eg: crimp and solder.
 
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Yea, crimp and solder is best. The instructions for the Anderson contacts say you can flood with solder and not touch up on grinder. The Anderson contacts are specific to wire gauge, even of the same color. Not mismatching keeps pre-solder play to a minimum. This is why I had gone up in wire diameter to 6 gauge for a pigtail to leave on the boat battery so my winch cable could be used for emergency jumping at sea. Anyway, I was just sharing my observation that the torch worked when the gun failed.
 
Blueone said:
You guys are too funny.... it’s a bit intimidating to post something technical on this forum...


Click to expand...
I appreciate seeing the Aussie fill the lug with hot solder before inserting the stripped wire. I'd coat the wire with flux first. Nice the way the insulation remains consistent. When I pre-silver, the leaded wire requires touching up in the vise to fit back in the lug. Crimping a #6 lug would require a hydraulic press.
 
Arminius said:
Crimping a #6 lug would require a hydraulic press.
Click to expand...
Crimping is still the best for a marine application. Soldering is fine, if done correctly, but should never be the ONLY means of attachment. No, you don't need a hydraulic press - there are plenty of inexpensive hammer punch tools available.

And, yes, you'll never heat a battery lug up with a soldering gun - a cheap propane torch is the tool of choice. MAP gas is even better.

I have used the solder lugs that Blueone linked to - for automotive applications :) Those are nice as they control the amount of solder being used, which is one of the key factors to avoid wire breakage over time from vibration right where the solder ends. Most people will use too much solder and it ends up creating a "hinge" where that solder ends which eliminates the natural flexibility of the wire strands.

Heating the wire up so much (soldering the "traditional" way) that the sheathing gets damaged means it was done wrong. Too much solder will get sucked in and under the sheathing, creating that hinge/pivot point.
 
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