[Aidan F. Browne]

Originally Posted by Aidan F. Browne

Al --

Please read the whole rule. The intent is that the connector provided in the kit is the connector that must be used. This is not an error.

"<R20> The 12v battery must be wired directly to a quick connect / disconnect connector (provided in the kit)"

As you can see, the rule clearly states that the connector is provided in the kit. The reason that the word "a" was used, is that there are two of the connectors provided (the entire connector is made up of two mirror-image halves).

Sorry to hear that all your previous equipment uses a different connector - but for 2004 the rule has changed.

All,

It is reasonable for you to ask for an explanation as to why you are being asked to use a 50A connector when you have experienced higher currents on your robots.

Here is the reasoning:

Anderson Power has been completely in the loop in selecting the connector for use in our application. They know what the specs are on the wires, breakers and maximum current draws. Anderson Power has determined that worst-case current draws do not exceed the true rating of the part.

Now - you ask - how can this be? Well - a commercial data sheet (in ~ 2 pages) tries to rate a part for use without knowing all of the conditions in which the part will be used. For this reason, data sheets are often very conservative. Once an actual application is studied - and all the environmental and usage characteristics are understood, parts are very commonly approved for use above their "rated" parameters. Time, frequency, temperature and other parameters all play into the "true" stress rating of a part. This is the case here.

To alleviate any of your concerns about a single SB50 connector carrying the entire current load for your robot, understand that in addition to Anderson's analysis of the situation, worst-case testing has been performed. Basically, tests have been run where a fully-charged Exide battery has been connected to the kit breaker through an SB50, and then the output leads downstream of the breaker were shorted in "crowbar" tests. The SB50 performed acceptably, was not overstressed and did not exceed its "true" ratings.

Now -- before you cry foul -- yes - there have been some part failures -- the worst known was the famed "WPI connector" from last February -- the picture of which has been widely distributed. That part was returned to Anderson and an extensive root-cause investigation was performed. It was proven that the reason that happened to that connector was that the two haves of the connector were only halfway connected and that there was only a point contact between the contacts. So - the failure was not because the part was overstressed, but that the part was not used as designed.

So - bottom line -- the Anderson connector is adequate for use on FIRST robots. There are over 25,000 successful uses of the connector in real FIRST matches. The 2004 rule is that you must use this connector. It is safe. The only concern is to make sure that you leave enough slack in your 6 AWG wire to ensure that you can properly mate the connector. It is also good practice to zip-tie the connector together each match to ensure it does not partially separate during impacts in competition (although this is not required).

Hope this helps alleviate the confusion and frustration.



Aidan