pic: Battery connector.....

[apalrd]

The weight of a plastic connector is a drop in the bucket compared to the brick of lead, which varies by pounds between batteries of different manufacturers.

The big advantage is in current carrying capacity, which FIRST already limits using the 120a breaker. Most of the benefits are thermal, and prevent the wires from becoming sticky or melting (we frequently run the robot hard enough for the #6 wire on the battery to become sticky in 1 match time, at the very least it's always warm to the touch).

IMHO, the goal is usually to reduce weight for performance. If we ever are trying to add weight, it's always for CG management (esp. the 2012 bridge balance, or 2013 hanging).


I really want to put an end to the near-failures of the main power system we see every year. Even if the connectors don't fail catastrophically like the one in this picture very often, the wires are always sticky, and showing signs that they are undersized. And even if the connector is adequate, we can't easily put a larger wire in the connector, even if there are no rules prohibiting us from using a larger wire (currently we can use #4 wire for the battery side cable, so any argument of weight or capacity of the wire is null).

[Al Skierkiewicz]

Originally Posted by apalrd

The weight of a plastic connector is a drop in the bucket compared to the brick of lead, which varies by pounds between batteries of different manufacturers.

I assume you are talking about the battery. If your battery weighs less than 12 to 13 pounds, you have vented a considerable amount of moisture to the atmosphere. There is a difference in the FR rated case but then again slight. Otherwise there is little difference in batteries.

[apalrd]

Originally Posted by Al Skierkiewicz

I assume you are talking about the battery. If your battery weighs less than 12 to 13 pounds, you have vented a considerable amount of moisture to the atmosphere. There is a difference in the FR rated case but then again slight. Otherwise there is little difference in batteries.

We found that our gray batteries weighed on average 13 pounds, while the black-top ones weigh 14 pounds. I assume there is similar variance between manufacturers. OCCRA weights robots with the batteries, so we weigh all of them to find the lightest one to weigh in with.

The weight difference between the SB50 and SB120 plastic connectors is far less than a pound, so the weight difference isn't a significant advantage.

[Al Skierkiewicz]

http://www.chiefdelphi.com/media/photos/39426
Check out this from 2004, found my electrical students as we check through and unpack our boxes from our other build space.

Joe as promised...

[Bill_B]

Originally Posted by apalrd

The weight of a plastic connector is a drop in the bucket compared to the brick of lead, which varies by pounds between batteries of different manufacturers.
....

Of course, I know this. I was merely positing the reason for rejection by the GDC. Whether the reason for the ruling is weight, current or dyspepsia is all a matter of conjecture anyway. Making your case(s) for a larger connector here may be considered preaching to the choir but keep it up now that we have been assured that there is some notice of CD being taken by the GDC. I'm not sure when the transition to happens but as long as Al is talking, I'm listening.

[Al Skierkiewicz]

In the event of a frame fault, the cRio and/or DSC can produce some really crazy issues. In this case I suspect that the fault may have caused multiple motors to turn on in opposite directions or were commanding movement when none was possible. Why? High current in the #6 wire has to go someplace. If it shorted in a #18, then the breaker trips and the wire goes poof. If multiple loads are drawing extreme currents, then no breakers trip and no other wire gets hot enough to melt. When robots get crazy, suspect a frame fault first and look for it. It is sometimes difficult to find. You can try by pulling breakers and adding them back one at a time while looking for the issue. This is how the Banebot shorts were found a few years ago.