My vote would be coincidence. I have been maintaining large arrays of cells
and batts since '79 and have never noticed a pattern of failed cells.
Always random.
Now, if we are talking the same UPS, one end could be hotter.
-----Original Message-----
From: Ken Hohhof
Sent: Friday, December 9, 2016 7:15 AM
To: [email protected]
Subject: Re: [AFMUG] another battery question
The first explanation doesn't make sense, the second is more likely. Or
just coincidence.
So you need to rotate your batteries?
-----Original Message-----
From: Af [mailto:[email protected]] On Behalf Of George Skorup
Sent: Thursday, December 8, 2016 9:55 PM
To: [email protected]
Subject: [AFMUG] another battery question
I've got a Tripp Lite 2U UPS that recently needed new batteries. They have
two internal 48v strings. 4x 12v 5Ah per string. Ordered completely OEM
replacement string, threw them in, everything is fine.
The old ones however would cause the UPS to shut down instantly when AC was
lost. I figured I'd find one bad 12v battery pulling the whole thing down.
No, instead each string had one bad battery. What's odd is that the two bad
ones were both at the "end" of the strings. The other six tested fine.
I've seen this multiple times now on different stuff. If all of them aren't
bad, it's always the battery at the end. I've noticed this on 24 and 48v
systems. My question is why? Is that battery taking the brunt of the surge
current upon transfers?
The other thought I had with this Tripp Lite thing is that both of those
batteries were probably the closest to the heat generating components,
inverter, etc.
