Herbert Graf wrote:
> On Fri, 2009-05-01 at 00:14 +0500, Hasan A. Khan wrote:
>> Hi all,
>>
>> I recently purchased a used APC SmartUPS 2200VA UPS at a dirt cheap 
>> price.  It was cheap because its batteries were near the end of their 
>> life.  Replacing the batteries with the same kind of dry cell lead acid 
>> is prohibitively expensive here.  I was thinking I would replace them 
>> with ordinary wet cell automotive batteries because they are really 
>> cheap.  These wet batteries are not the maintenance-free type and they 
>> won't obviously fit in the casing.  I will have to keep them watered but 
>> that's ok by me.
> 
> Frankly, it's been a while since I've seen a car battery that wasn't
> maintenance free. Adding water? That's a long time ago.

Actually if you look at most of them carefully the cheaper (non-AGM 
style) "Maintenance Free" batteries, the little cell covers come right 
off on top, and lo-and-behold, there's the good old fashioned battery -- 
same tech it always was.  The only difference is the seals have gotten 
better, so less water evaporates.  I've found "maintenance free" 
batteries that needed distilled water badly, came right back to life 
when "maintained".   Go figure.

> What you need a "deep cycle" batteries. They are more expensive, but are
> designed for the kind of load a UPS is.

Like these...

http://www.cdstandbypower.com/product/battery/vrla/pdf/12_310.pdf

I got lucky and got four of these from a site that was required to 
"decommission" them every couple of years, whether they needed to or 
not.  Many critical big rack-mounted UPS systems are required to replace 
their batteries on a schedule, no matter their condition.  These were fine.

Nate
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