Battery Leads and Resistance

[Andy A.]

It's worth noting that poor crimps and loose terminals are probably a much greater source of resistance in the battery cables then the wire itself. Remember to periodically check that the stud terminals on the breaker and PDB are tight; they can and do loosen up over time. Also check whatever terminals you have put on the ends of the six gauge. A lot of teams have problems getting a reliable crimp on these much larger wires. If you go the crimp route, make sure you have an adequately sized tool and whoever does it has the strength to use it correctly.

Also, the Anderson connectors are well made but sometimes the contacts get a little charred or the crimp comes loose. Take a look at the contacts and give the wires a wiggle to verify they are clean and tight.

[Joe Ross]

Originally Posted by Andy A.

Also, the Anderson connectors are well made but sometimes the contacts get a little charred or the crimp comes loose. Take a look at the contacts and give the wires a wiggle to verify they are clean and tight.

Here's what might happen if the Anderson connector is not fully engaged: http://www.chiefdelphi.com/forums/sh...threadid=18079 (Further explanation: http://www.chiefdelphi.com/forums/sh...0&postcount=20)

[Al Skierkiewicz]

Boy Joe, you took a long ride in the way back machine. In reality what we no know about these connectors is that one failure seems to override all others. Teams who use alligator clips (those supplied on the battery charger) to connect to the battery for charging, will scratch the contact surface. This causes there to be high spots on the surface of the contact that severely limit the area through which current is passed from battery to robot. The reduced area translates to higher series resistance. Ohm's Law tells us that if you raise the resistance, while keeping the current the same, increasing power is dissipated in the area of the resistance. When you try to pass several hundred amps through that pinpoint of contact, significant heat is generated. That heat can be excessive enough to melt the housing, fuse the contact(s), heat the wire attached to the terminal and it limits the amount of current available to drive the robot. There are other failures to be sure, but contact damage is the most prevalent.

[Mr V]

Originally Posted by Andy A.

It's worth noting that poor crimps and loose terminals are probably a much greater source of resistance in the battery cables then the wire itself. Remember to periodically check that the stud terminals on the breaker and PDB are tight; they can and do loosen up over time. Also check whatever terminals you have put on the ends of the six gauge. A lot of teams have problems getting a reliable crimp on these much larger wires. If you go the crimp route, make sure you have an adequately sized tool and whoever does it has the strength to use it correctly.

Also, the Anderson connectors are well made but sometimes the contacts get a little charred or the crimp comes loose. Take a look at the contacts and give the wires a wiggle to verify they are clean and tight.

You are correct adding another 5' of wire only adds another .002 ohms of resistance when using 6a wire. In other words not enough to have a noticeable affect on performance.