Correct Methods

[Al Skierkiewicz]

I am starting this thread in the Technical Discussion because there are more than just electrical issues that need to be corrected. So for all you team members out there, this thread is for you.
Here are some suggestions on how to prevent shooting yourself in the foot...

1. The WAGO connectors on the PD require 1/2"-5/8" of bare wire to terminate. This gives you the maximum amount of retention force and the minimum resistance.
2. Never "tin" the wire you use in a WAGO terminal, a screw terminal, or a crimp terminal prior to crimping. This increases the series resistance and often causes the wire to push out or loosen. Properly terminated, the WAGO terminal should have no bare wire showing and should resist the "tug" test. This holds true for other applications as well, FTC students I hope you are listening.
3. Using a smaller breaker does not limit the current going to that motor or load. It may cause the breaker to trip more often which may not be what you want.
4. Insulate electrical connections. At the top of the list, the battery, always, all the time. Metallic objects dropped onto the terminals of the battery can weld themselves in place. This includes neck chains, bracelets, tools, aluminum robot parts and the legs on the table in your pit.
5. Be careful with the PD, those are metric nuts and washers on the input side, not 1/4-20. Damage those and the PD becomes a very expensive paper weight.
6. Learn what the correct strip length is for the wire terminals you are using. If you do not remove the correct length, the wire will not be fully crimped with the terminal. A correctly crimped terminal actually "cold welds" the terminal and the wire. When you crimp you are forcing the wire and the terminal into a solid mass with no air spaces.
7. Never lift the battery with one hand or by the wires. I don't care if you lift weights and are really strong, the battery is 13 pounds of dead weight and it will move where and when it wants if you let it. Be the boss. Lifting by the wires will break the bond inside the battery. These batteries are designed to have a variety of different terminal types. They merely solder the terminal at the end of production and then pour the red and black plastic into the void to finish the manufacturing process. You can break the joint and never know it, until it fails in your last match on Einstein.
8. Loose hardware on the battery causes the robot to reboot, excessive heat at the terminals, and untold team frustration. Buy a bag or box of #10 external tooth lock washers. Place one lock washer between the wire terminal and battery terminal and then insert the screw, lock washer and nut as you would normally. The added lock washer will prevent the terminals from twisting against each other. It is this twisting that loosens the supplied locking hardware. Yes it may add a little series resistance to the connection but it bites through any surface crud on either terminal, and it locks the connection together.
9. There is no substitute for using a tool designed for the task at hand. That means if you need to add force to an object to get it to move, you use a hammer. Do not use the $100 crimp tool, the crescent wrench, or the gas pliers. If it doesn't move maybe you are doing it wrong or maybe you just need to get a bigger hammer. Learn to know the difference.
10. As always, there is no reason to have your safety glasses on the top of your head when you are working. Every person walking around with a ding in the lens will be willing to tell you how this simple $5 tool saved them from harm. Live safe, live long, pass on what you know. More to come...

[Bill_B]

Find a pair of safety glasses that are comfortable enough to wear all the time. Put your name on them and make sure they go with you everywhere you're likely to need them. I know mine are OK when I discover them still on the bridge of my nose as I pull out of the parking spot at our build site. Never mind how "goofy" they make you look. An eye-patch to cover your disfigured optics will look goofier by at least an order of magnitude.

[BigJ]

Originally Posted by Bill_B

I know mine are OK when I discover them still on the bridge of my nose as I pull out of the parking spot at our build site.

I know mine are OK when the team asks me at dinner at a regional why I still have my safety glasses on

Also, don't lift batteries with 1 hand anyway because you can totally pull a muscle in your thumb. I'm pretty sure I've done it or come very close a few times in my FIRST career.

[Nate Laverdure]

Originally Posted by Bill_B

Find a pair of safety glasses that are comfortable enough to wear all the time. Put your name on them and make sure they go with you everywhere you're likely to need them.

Better yet, if you're enjoying the work and you think you might want to spend even more time doing it, ask your parents to drive you to the local hardware store and buy a couple pairs of your very own. Your mentors will be very impressed by your motivation and they might start sharing more of their secrets.

[DonRotolo]

Originally Posted by Al Skierkiewicz

4. Insulate electrical connections. At the top of the list, the battery, always, all the time. Metallic objects dropped onto the terminals of the battery can weld themselves in place. This includes neck chains, bracelets, tools, aluminum robot parts and the legs on the table in your pit.

Students are just clueless when I ask them how much energy is stored in a battery. The FRC Battery can make a wrench glow red hot in a few seconds....just before the wrench vaporizes...unless the battery explodes, of course. In that case, picking chunks of lead and plastic from your body - all covered in concentrated sulphuric acid - will occupy your time instead of having to treat the holes from the molten steel wrench where it burned through your arm. At least it cauterizes the wound, most of the time.

Too gruesome? Try seeing happen, live and in person.


.

[Ether]

Originally Posted by DonRotolo

Students are just clueless when I ask them how much energy is stored in a battery. The FRC Battery can make a wrench glow red hot in a few seconds....just before the wrench vaporizes...unless the battery explodes, of course. In that case, picking chunks of lead and plastic from your body - all covered in concentrated sulphuric acid - will occupy your time instead of having to treat the holes from the molten steel wrench where it burned through your arm. At least it cauterizes the wound, most of the time.

Too gruesome? Try seeing happen, live and in person.


.

Or live it.

Back when I was young and immortal, I was working underneath my 68 Camaro changing the starter motor.

I didn't bother to disconnect the battery first.

My metallic watch band completed the circuit and it exploded off my wrist.

Which is a good thing, because if it had not, I'd probably still be wearing pieces of it.

[pmangels17]

As far as safety glasses, get yourself a pair of croakies or similar. Rather then setting them down when you don't need them (ie. when you are not in the pit/shop) and scratching them, they are always there and wont fall of your head and get scratched. Also if you have a big head like me, the AndyMark glasses are really great at not being uncomfortable.