Power/Battery Cable Routing Suggestions

I’ve dug around a little for information on this, but had little success. One of the main goals we have for our electrical team this year is to vastly improve our wiring neatness from past years.

Up to this point, we’ve had pretty good success with wiring from PD board and from controllers to motors thanks to suggestions such as zip wire, as well as some excellent wiring examples that we are using as a baseline.

Unfortunately, the connections which are most vital to the robot are often the most overlooked, the power and battery connections. The unruly 6 gauge wire makes the connections among the most difficult to make look clean, and I’m looking for any suggestions I can get whether it be specific products that make life easier, or general practices in dealing with these connections.

Thanks in advance.

I tell this to my students all the time. You are the boss! Make the wires do what you want. The nice thing about #6 is you can bend it and mold it to where you want it to go. Use your fingers, measure and place the wiring as you want it, then cut and terminate.

Yes, the #6 guage wire become unruly and cranky, especially after staying exposed to cold elements!

The best tip is to use as little big wire as possible. For every motor controller, shorter means less resistance to that motor, but for the main battery cable, it affects the whole robot. So keep it short. Even if it means slightly worse routing to get a straighter line.

The main battery cable is the one wire that I never really constrain in any way. It moves point to point as efficiently as possible without getting too close to mechanical components. I never try to include it in wire bundles, as this wire tends to get hot (sometimes to the point of being slightly sticky) and a bundle of wires around it would let it get even hotter. As solid as it is, it tends to hold it’s shape.

Battery to Main Breaker to PD Board layout and distances are critical to short cable runs. The battery includes a foot of wire, use it to your advantage to keep the main cable short. Draw a line (in your head) between the battery and PD board and put the main breaker on that line. Avoid the temptation to put the breaker feet away from that line ‘for easy access’, and find an area on or very close to the line which has sufficient access. You have to be able to get to it, but it does not have to be on the edge of the robot (in fact, I’ve seen side-mounted main breakers get hit during a match, and turn off).

As for termination, we’ve always used crimp connectors and dip soldered them. We use a large crimp press that we have access to. I can’t help with any easier way to do this, but wrap the connection in electrical tape neatly.

#4 is even more unruly.

Not all wire is created equal!

You can get super flexible six (or any) gauge wire. Check out McMaster for an example. It’s more expensive but much easier to work with and tends to reduce strain placed on crimped terminations while moving the wire around. If you have a local supplier of wire, ask them for ‘welding’ or ‘automotive’ wire. They’ll likely have something comparable.

Use crimp terminals with a hammer style crimper. http://www.mcmaster.com/#battery-terminal-crimpers/=qhx0gp

I solder the cable first, crimp, heat the terminal with a torch and then heat shrink.

Then buy yourself some more ruly wire, as Andy A suggests. Our high-starnd #6 wire is almost as limp as cooked spaghetti.

As for soldering: Generally a bad idea, since the solder wicks up int the wire and embrittles it. A proper crimp does not need solder, even with a hammer crimper.

Soldering after you crimp is okay, as long as you’re careful not to let the solder flow along the conductor outside the crimp. Soldering before you crimp is not okay. You won’t get a reliable proper connection that way.

Soldering after you crimp is also not a good idea. The whole point of a crimp is to connect the wire to the terminal with a gas-tight connection. If you crimp it properly, then soldering will not add anything to the reliability of the connection. It will, however, increase stress on the wire at the joint, running the risk of breaking wire strands.