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Unread 21-01-2006, 12:04
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: 10,763
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Re: Motors/Battery life

Quote:
Originally Posted by eugenebrooks
Al, I beg to differ...

We compared the capacity of the then new EX battery to year old ES batteries last year, and found the year old batteries to have 50% more capacity at a constant current 20 amp load. This year's milage may vary, but the batteries were quite different in performance when checked last year.

Eugene
Gene,
I will test our batteries, I have a CBA battery analyzer from Mountain Radio. I know that there was a manufacturing defect in some batteries last year. When discharged, at some point in time the output voltage suddenly dropped by 2.1 volts. Then later there was another sudden drop. Indication was that cells were shorting or of vastly reduced capacity. I will post when I know more. There should be no reason for a 50% difference between production runs.
Dale, I have to take issue with your methodology. The load testers are for short term testing. When you load to capacity over a long period of time the resistance changes with temperature. It is possible the load testers were changing value to a lower resistance.
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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.

Last edited by Al Skierkiewicz : 21-01-2006 at 19:11.