Soldering instead of crimping
Hi, Would there be any reason not to solder battery connections versus crimping? The application would be for a solar charging system. Moved to Tech Issues forum from DIY.
Forum Discussion
A few years ago, I posed the solder vs. crimp question to a product developement engineer for one of the larger suppliers of marine electrical wire, terminals and accessories. This is what he stated.
When properly crimped, tinned copper wire and properly sized tinned terminals do not require soldering. The crimping force generates enough pressure to fuse the tin on the wire to the tin on the terminal providing a near zero resistance to current flow.
The down side to soldering as well as crimping is that the copper in the wire as well as the terminal becomes brittle and subject to fatigue breakage. Copper is somewhat unique as a metal when it comes to heat treating. When steel is heated and allowed to cool slowly it becomes more maleable (softer) and flexible. Copper on the other hand becomes harder and more brittle when heated and allowed to cool slowly.
He did suggest however that high amperage terminals such as battery cable lugs be properly crimped as well as soldered. His reasoning was that if there is heat generated by the high amperage at the terminal, it could break the electrical bond of the thin tin plating and cause some resistance. Resistance causes more heat and that increases the resistance even more etc. etc. His reccomendation was that terminals 8 gauge and larger (6,4,2 ect.) be properly crimped and then soldered. The fatigue factor due to the tempering of the copper is not as large a factor due to the strength of the larger wire.
If soldering is to be done, only resin core solder is to be used, never acid core or soldering paste. As well, the solder should be 50/50 (lead/tin) or better. The newer solders have replaced the lead with other metals (antimony?).
Lastly, he emphasized that the connection, especially in the marine enviroment, must be sealed to prevent corrosion from water and humidity. Adhesive lined heat shrink is highly recomended as well as anti-corrosion spray or grease.
We have been using the above proceedures for many years in commercial boats used in extreme salt water enviroments. None of our connections have failed at the wire/terminal connection.
When properly crimped, tinned copper wire and properly sized tinned terminals do not require soldering. The crimping force generates enough pressure to fuse the tin on the wire to the tin on the terminal providing a near zero resistance to current flow.
The down side to soldering as well as crimping is that the copper in the wire as well as the terminal becomes brittle and subject to fatigue breakage. Copper is somewhat unique as a metal when it comes to heat treating. When steel is heated and allowed to cool slowly it becomes more maleable (softer) and flexible. Copper on the other hand becomes harder and more brittle when heated and allowed to cool slowly.
He did suggest however that high amperage terminals such as battery cable lugs be properly crimped as well as soldered. His reasoning was that if there is heat generated by the high amperage at the terminal, it could break the electrical bond of the thin tin plating and cause some resistance. Resistance causes more heat and that increases the resistance even more etc. etc. His reccomendation was that terminals 8 gauge and larger (6,4,2 ect.) be properly crimped and then soldered. The fatigue factor due to the tempering of the copper is not as large a factor due to the strength of the larger wire.
If soldering is to be done, only resin core solder is to be used, never acid core or soldering paste. As well, the solder should be 50/50 (lead/tin) or better. The newer solders have replaced the lead with other metals (antimony?).
Lastly, he emphasized that the connection, especially in the marine enviroment, must be sealed to prevent corrosion from water and humidity. Adhesive lined heat shrink is highly recomended as well as anti-corrosion spray or grease.
We have been using the above proceedures for many years in commercial boats used in extreme salt water enviroments. None of our connections have failed at the wire/terminal connection.
