[rescue] Any recommendations on rack-mount UPS?

Robert Darlington rdarlington at gmail.com
Mon Oct 12 15:19:02 CDT 2009

The problem isn't so much that it's APC, it's that APC uses gel cells (aka,
SLA or sealed lead acid).  These batteries swell, and sometimes even pop.
AGM batteries do not do this.  AGM batteries cost more, but it seems APC
does sell some units with these batteries.  I hate gel cells, but do use
them occasionally where swelling isn't a concern, such as on my bicycle for
the headlights.  I would never consider them for something that mattered
though.  You won't see them in airplanes or submarines and you won't see
them in my server room.

A friend of mine worked with the state of Florida on some railway project.
By random luck he noticed that there were service techs at railway crossings
changing batteries for the lights that are used in case there is a power
outage.  He chatted them up about it and found out that they changed their
SLA batteries out roughly once a month.  Pat worked with them to come up
with a solution.  The first part was to add a heat shield (just a piece of
aluminum over the box, spaced an inch or two over the box) and paint the box
white (NOT silver).  The other part was to replace the batteries with AGM
batteries.  Most of the batteries have now been in use for 26 years
continuously.  Gel cells can't take the heat, but AGMs don't like to be deep
cycled.  There are trade-offs, and I prefer to shut down servers before
depleting the batteries (which results in just a delay before the cord gets
yanked)  This keeps the AGM batteries happy and it sure beats trying to pry
out swollen batteries.

On Mon, Oct 12, 2009 at 10:56 AM, Robert Darlington
<rdarlington at gmail.com>wrote:

> Consider Liebert.  In my circle, APC sells junk.  No matter what, if you
> care about it, I'd go with AGM batteries in the very least.  You'll wish you
> did when the day comes and you need to get the old gel cells out, but you
> can't because they swelled up and are permanently locked inside the
> equipment.
> -Bob
> On Mon, Oct 12, 2009 at 10:40 AM, Rich Kulawiec <rsk at gsp.org> wrote:
>> Thanks, everybody -- I'm going with your recommendation(s).
>> ---Rsk
>> _______________________________________________
>> rescue list - http://www.sunhelp.org/mailman/listinfo/rescue

More information about the rescue mailing list