Battery Connector Issue

Blog Date: 
Monday, January 14, 2013 - 17:05


We were alerted over the weekend to an issue with some of the battery connectors supplied in the Kickoff Kit and FIRST Choice. The wires and connectors were improperly assembled, creating the opportunity for a team to mis-wire the battery to the Power Distribution Board. Figure 1 shows properly and improperly assembled connectors, where the black cable goes into the positive position on the Anderson Power Products connector.

Assembled Cables

If an improperly assembled cable is connected with a properly assembled cable to complete a circuit between the robot battery and the PDB, damage can be done to the electronics in the robot (cRIO, Digital Sidecar, etc.). Figure 2 shows possible connection issues. Situations 2 and 3 require rework of the improperly assembled cable.

Potential Connection Methods

To correct this problem, the Supplier recommends using a small screwdriver to depress the spring-steel under the contact. This allows the wire and its contact to be removed. Once both wires are removed, they can be re-inserted in the proper orientation (i.e. red to the positive terminal on the Anderson Power Products connector, black to the negative). A short video showing the removal of the wire from the connector has been created and is available on YouTube.

If damage was caused to any control system components because of this error, please contact us at frcparts@usfirst.org.

Comments

For the diagram with the one incorrect cable the wires should not be crossing over. the black cable should end up in the positive side of the board and the red in the negative side. If wired the way it is shown it would cause damage to the components.

Hi Jared, you're correct that the image is showing that the cables can cross, which will cause damage to the CS components. This is why the blog states (just before the image): "Situations 2 and 3 require rework of the improperly assembled cable." Hope that helps!

Just saying hi, from team 2013

I'm afraid I don't understand why situation 2 is problematic. The positive on the battery is still connected to the positive on the PDB, and likewise with the negatives. Why would this be an issue? Is there something else important inside the connector?

Re: "Confusion", because if you purchase any new connectors or connect old batteries with proper connectors, you will end up crossing the connection such as in Figure 3.

You're right re. the factual flow of electrons, situation 2 does provide the correct unidirectional flow of current through circuit electronics. The issue is one of anticipating what someone not familiar with the wiring issue described here might do: notice that the + and - on battery and power board don't match the connectors, and think they are "fixing" a problem by flipping one of the connectors thus doing harm rather than good. A little knowledge is the most dangerous situation, you always want to make sure both your design *and its implementation* innoculate your system from "helpers"

When the Power to the Power Distribution Board was applied with the correct polarity from 0 - 3V DC. The power supply 2 of the LEDs lit up but the Board failed. The 24V supply came up to 23V, abd the 12V to 5v. Team 744 has 2 Board that act the same. The one from 2013 Kit and Spare from 2012. The Q12 FET and TVS1 24V Zener are suspect. A 2.4V Zener would cause this problem. - Ralph

Two comments:

1. There is a '+' and a '-' moulded into the connector that may make it easier to check for correct assembly. The red wire should be in the '+' side and the black wire should be in the '-' side.

2. If you fix this issue by swapping the wires where they attach to the battery, the power distribution board (PD), and main circuit breaker, firstly the inspectors at the competition will make you fix it, and, secondly, if the inspectors somehow don't notice (and they will be looking for it), if you borrow a battery from another team, your robot's control system may be destroyed

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