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Unread 01-10-2014, 08:02
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
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Re: Which Battery to Buy?

Andrew,
I received a very informative reply from Midtronics Tech Support on these testers. It is my understanding from the reply that the CCA test does not use a load and does not require a fully charged battery. The test makes a calculation based on a "conductance" test. The test generates an AC waveform that is used to determine the internal conductance of the battery. This is an indication of the available plate area within the battery. That value is then used to generate a CCA display in the unit. This value when used with other tests that the device performs can determine the true health of the battery without a lengthy test. The manufacturer does recommend that any odd readings be performed a second time after the battery is fully charged as well. The full set of readings, if interpreted correctly, can point to a battery with a failing cell or a battery that is nearing end of life and therefore good for practice but not competition worthy.
Tech support also provided me with a document titled "Transportation Battery Testing Q&A" that describes the test in more detail. I also did a search of their website and found this page...
http://www.midtronics.com/transporta...t/technologies
It has several informative articles on batteries and testing. My contact suggested that the larger tester may not give you the most accurate readings on FRC batteries as they are designed with "wet" cell batteries in mind. Since our batteries are not specified in CCA, users will have to come up with a "good" CCA value when using this test.
I would like to thank Midtronics tech support for their helpful and hasty reply. I was fairly impressed with their website and product line. It is easy to see why they are the official battery tester for NASCAR. I would like to see one of these testers in use if anyone has a unit at an event I attend.
Tech support suggested that a MDX-640 might be a better device if a team is looking at Midtronics testers.
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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 : 01-10-2014 at 09:22.