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BMS leads, Solder or crimp

shavermcspud

Solar Enthusiast
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What have others done on their BMS leads to cells?

Do you solder or crimp?

I've read mixed feedback that soldering adds unnecessary resistance for the mV readings we need, despite a decent wet solder connection.
Others have said that crimping allows for potential corrosion to form.


Feedback from your experiences please.
 
What have others done on their BMS leads to cells?

Do you solder or crimp?

I've read mixed feedback that soldering adds unnecessary resistance for the mV readings we need, despite a decent wet solder connection.
Others have said that crimping allows for potential corrosion to form.


Feedback from your experiences please.
I crimped.
Since its a climate controlled stationary installation I'm not worried about corrosion.
 
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EE opinion - at zero current, even resistive connections cause zero volts error.
Dissimilar metals and temperatures can cause voltage, typically more an issue for microvolt measurements.
Good crimps and good soldering are both good enough for the benign environment around lithium cells. (FLA and marine environments require more protection like sealing around stranded wires.)

Focus your attention on current-carrying contacts, especially those involving aluminum. That is, the path to inverter and charger, not to BMS sense wires.
 
Crimp it! Crimp it good! (To the tune of Devo's "Whip It")

A solid crimp, with the proper terminal and heat shrink tubing isn't going to allow air/moisture in. I bought small gauge ring terminals that included the heat shrink tubing. It took me a while, and a few nasty crimps, to realize I was using the wrong crimper for terminals that included the heat shrink tubing.
 
Crimp it! Crimp it good! (To the tune of Devo's "Whip It")

A solid crimp, with the proper terminal and heat shrink tubing isn't going to allow air/moisture in. I bought small gauge ring terminals that included the heat shrink tubing. It took me a while, and a few nasty crimps, to realize I was using the wrong crimper for terminals that included the heat shrink tubing.
I you're like me, you have lost count how many crimpers you have. Each has its place, and forte. Using the right crimper for the right job is 2/3rds of the battle.
 
I you're like me, you have lost count how many crimpers you have. Each has its place, and forte. Using the right crimper for the right job is 2/3rds of the battle.

Yep, lots of crimpers. Lots of them with no markings, no directions. I had no clue which one to use. I was all set to order a new die just for the terminals with heat shrink tubing. Just before I hit the button I went through my dies and found one that matched the picture online.

I'm also considering ditching the terminals that come with heat shrink. A terminal that you can actually see the crimp and visually verify that it's good, can always be subsequently covered in heat shrink.
 
Yep, lots of crimpers. Lots of them with no markings, no directions. I had no clue which one to use. I was all set to order a new die just for the terminals with heat shrink tubing. Just before I hit the button I went through my dies and found one that matched the picture online.

I'm also considering ditching the terminals that come with heat shrink. A terminal that you can actually see the crimp and visually verify that it's good, can always be subsequently covered in heat shrink.
The weirdest might be the special crimper needed for insulated right angle "flag" push on terminals. There really is no good way to crimp these, without this tool.
 
The weirdest might be the special crimper needed for insulated right angle "flag" push on terminals. There really is no good way to crimp these, without this tool.

Yep, got one of those dies (now). I used a set of Vice Grips to crimp an insulated flag terminal last year. It worked, but it wasn't looking too good. Fortunately, it ended up behind a wall in the RV. Flag terminals are kind of an oddball connector. I suspect I won't need to use another one for a few years. By then, it will take me only two hours to find the die. :)
 
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