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Unread 09-02-2012, 12:06
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: 10,792
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Re: Battery upside-down

In most cases, dangerous gasses are mostly generated during charging. Although normal use (discharge at 1/10-1/2 C) shouldn't produce increased pressure within any cell, our use can cause some additional heat to be generated. While acid leakage is not a huge concern, these batteries do tend to produce some internal condensation. If the battery is used upside down, and the internal pressure were to cause a vent to open, some of this condensation would be lost. Over time, this will reduce the available current from a given cell.
My usual recommendation is never charge upside down and don't use upside down if at all possible. When the battery is inverted, you can see where the terminals are located in relation to the robot structure or other electrical connections. This is a possibility for battery failure either through shorting to structure or damage to the terminals on the battery.
One must remember that this battery is manufactured such that a variety of terminations can be used with the same basic battery configuration. The terminals on our battery simply push over two round terminals inside the battery and then are soldered in place. It is possible to break the solder bond internally without any visible external damage. The result is significant voltage drop and heat. The battery may test good with a voltmeter, it may even charge normally but will fail either intermittently or through voltage drop on the field.
Finally, I have to remind all teams that securing the battery is part of the inspection checklist. You have to demonstrate this during inspection. If you are on the field and the battery drops out of your robot, you will be disabled for the remainder of the match.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.