Thread: Battery Smoke
View Single Post
  #19   Spotlight this post!  
Unread 24-04-2007, 07:43
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,798
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Battery Smoke

Quote:
Originally Posted by RyanN View Post
We use a bolt with nylon lock nuts to secure our terminals to the battery. This year I wrote a message on all of our batteries on the proper way to carry them.

It took me about 5 minutes to figure out, but what I want to know is why the screw holes on the gear tooth sensors are grounded?
Ryan,
Your method is one of the better ones I have seen. Unfortunaltely, the softer metals that make up the battery terminals and the copper wire terminals will deform with time under that kind of stress. So check them on a regular basis just to be sure.
The gear tooth sensors are infamous for causing the kind of circuit to frame short you describe. Many designers use this method of grounded mounting holes to help reduce noise and insure that part of the circuit is at the same potential as the frame. In our competition, FIRST has made a decision that the frame of robots remain neutral. I agree with this decision simply based on the electrical designs I have seen over the years. As this thread has pointed out, the battery is capable of significant (welding) currents. As such, I would not want a robot to be electrically destroyed by the failure of another team to insulate sensors or custom circuits. There are nylon shoulder washers used to insulate power transistors that can be effectively used to insulate the sensor packages from robot frame.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.