Quote:
Originally Posted by wilsonmw04
Yes, wires were getting noticeably warmer.
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It seems to me that you were having issues not related to the length of the wire, but likely the quality of the splicing.
When splicing wire, I generally tend to never allow soldering wire gauges larger than 16. The reason is that with large wire gauges you effectively have two large heat-sinks drawing the heat away from the connection, and it's incredibly easy to end up with a cold-solder joint. In those situations, the joint (and subsequent wire) will be prone to internal arcing, heat buildup, and poor connectivity.
I don't think the actual length of wire had anything to do with your problem. Generally speaking, #12 wire has 4 times the resistance of #6 wire. As a general rule of thumb, if your battery and your motors are in fixed positions but your PDB can be moved around it's always best to use more #6 wire to allow your PDB to be closer to your motors than to use more #12 wire to allow your PDB to be closer to your battery. "Big Al" has, on many occasions, talked about the per-foot resistance of #10 and #12 wire, and has proven that there are "noticeable" and "non-insignificant" voltage drops that can be avoided by using #10 wire for motors (instead of #12) and reducing the length of that #10 wire as much as possible.
Also, I generally tend to prefer crimp connections (even for lengthening wires) over soldering the wires together. For the same reason it's done in home electrical systems, crimp connections tend to be less prone to mistakes and can be done relatively quickly. If you're concerned about the crimp connection, you can very often also solder the mating location of the crimp connector to ensure it won't go anywhere.
One last piece of wisdom, I generally tend to not trust screw terminals, especially for large-gauge wire (anything larger than 20AWG). Most of the screw terminals in this class I see used in FRC are the ones used to connect the batteries to the 6AWG battery wires - they have a ring terminal on one end to connect to the battery, and a screw connector on the other to create a press-fit onto the 6AWG wire. Wire tends to "spread out" and settle, and this means your connection will eventually become loose - this creates voids between your wire and the connector causing arcing, heat buildup, and poor connectivity. When teams tell me their batteries aren't keeping a charge or are taking a long time to charge, or their wires are heating up (and obviously the robot isn't using some 6-CIM beastly transmission), I usually check the batteries and have them tighten/maintain/replace the connector to the battery and that usually solves the problem.
Be well.
-Danny