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Unread 19-12-2009, 21:07
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: Historic Size of Battery

The document that Tristan has linked to is part of the references I have used in the past. The current battery is an AGM style battery so the electrolyte is absorbed in a mat but can become fluid under certain conditions. I recommend charging upright so that any fluid that might be present doesn't cover the pressure valves. Should pressure build to the point of venting, loss of fluid is inevitable. For the students handling batteries, if we make it a normal procedure to charge upright, then should they be in position where they are charging some other types, the vents will likely be facing up. If the battery experiences some failure during charging, then all venting will take place where pit crews can see it and react ASAP. We are not sure at this point what failures may have occurred, but a small number of teams have experienced battery failures over the last two years. Some have occurred during charging and the rest appear to be physical damage. Since the battery stores a large amount of energy, physical damage can cause internal heat. The domino effect causes venting, external heat, and leaking fluid. Please instruct your students to never handle the battery by the wiring, always carry with two hands and in the event of a drop, be sure to put the battery on the side until you (or another mentor) can determine if it has internal damage. A few hour test with a load tester like the West Mountain Radio CBA II will show if one or more of the cells have a reduced capacity indicating internal damage.
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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.