pic: ummm......what?

[Cory]

Originally Posted by EricH

Unplugging the battery when the circuit is on carries a risk of sparks, guys. I would not suggest trying that--ANYWHERE. That's why I asked.

Don't be overly dramatic. I've seen this done hundreds of times. No problem.

The simplest way of doing things is usually the best. No need to concoct some scheme when you can just do this.

[kiettyyyy]

Originally Posted by Cory

Don't be overly dramatic. I've seen this done hundreds of times. No problem.

The simplest way of doing things is usually the best. No need to concoct some scheme when you can just do this.

There's little to no current being sourced while the bot is still booting up... There should also be little to no current if you're some how up close to the bot without it running around.

Those "sparks" really only fly when you're dealing with MUCH higher potentials(200 VDC++).

It's no big deal.

[Bill_B]

You won't have to go very far into Electrical Engineering before you find out that sparks at disconnection are largely due to inductive loads, viz. motors and transformers. Inductors try to maintain current in their circuits. To do that voltage will increase across a switch as it opens and increases resistance. Eventually the switch "wins" and makes a very high resistance in the air gap, but not before a large inductor load tried to jack the voltage very much higher than usual. Sometimes the voltage spike will actually get high enough to cause current to jump the minuscule air gap as a switch opens. Result? Sparks. Not usually a good thing, so quite a bit of E.E. talent has been devoted to this solving problem.

As it applies here, if motors weren't running when you pulled the battery plug, there is very little chance of noticeable sparking. Voltages in FRC robot-land are usually quite low, so bare-skin contact is not a great danger. However, if the hand in contact has metal jewelry or tools in it, the danger of high current short circuit should not be ignored. I sometimes think that a you tube video of egregious electrician's behavior should be made to convince "kids" how easy and calamitous such short circuit "welding" can be.

[Andrew Y.]

Originally Posted by Alex Cormier

Unplug the battery?

Originally Posted by Bill_B

You won't have to go very far into Electrical Engineering before you find out that sparks at disconnection are largely due to inductive loads, viz. motors and transformers. Inductors try to maintain current in their circuits. To do that voltage will increase across a switch as it opens and increases resistance. Eventually the switch "wins" and makes a very high resistance in the air gap, but not before a large inductor load tried to jack the voltage very much higher than usual. Sometimes the voltage spike will actually get high enough to cause current to jump the minuscule air gap as a switch opens. Result? Sparks. Not usually a good thing, so quite a bit of E.E. talent has been devoted to this solving problem.

As it applies here, if motors weren't running when you pulled the battery plug, there is very little chance of noticeable sparking. Voltages in FRC robot-land are usually quite low, so bare-skin contact is not a great danger. However, if the hand in contact has metal jewelry or tools in it, the danger of high current short circuit should not be ignored. I sometimes think that a you tube video of egregious electrician's behavior should be made to convince "kids" how easy and calamitous such short circuit "welding" can be.

a little late, but i will comment...

I agree that there is little load when disconnecting the battery. Connecting the battery has a greater chance due to the capacitors charging the instant they are connected. soo basically we are not supposed to plug our batteries in because of spark.

@Santosh....ill see you thursday night...and we can duke it out. Selling tickets to see the fight for $450 a seat.