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From: "Boris Nogoodnik"
Subject: Re: UPS - Sealed lead acid battery.
Organization: KGB, Ltd.
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Sat, 5 Oct 2002 07:31:54 -0400
NNTP-Posting-Date: Sat, 05 Oct 2002 07:31:52 EDT
"Kevin McMurtrie" wrote in message
> In article <email@example.com>,
> firstname.lastname@example.org (HuweyII) wrote:
> >I have three UPS's (APC Smart-600) which I'd like to continue to use
> >each reports "replace battery"
> >Anyway I've replaced the batteries in all three 6 - 12 months ago, and
> >was fine for a while but all three have slowly started reporting
> >"replace battery" again.
> >So I figured maybe these three UPS's arn't charging the batteries,
> >possibly they sat OK for a while but at some point the voltage dropped
> >low enough for the UPS's to report a bad battery.
> >I'm trying to figure out if I'm looking at a UPS that isn't charging
> >or real bad batteries. (BTW, if I connect a small load, 150w or so,
> >to the UPS and remove mains power it will turn it self off almost
> >immediately due to low voltage)
> >Each UPS has two 12v 6ah sealed lead acid batteries connected in
> >I'm curious if what I'm seeing is about right for these unit's to be
> >charging these batteries.
> >My pair of test batteries sit at 23.94v with no load.
> >When power is applied to the UPS's they give the batteries about
> >27.45v at 140mA, however one of them gives about 310mA at about the
> >same voltage.
> >Are these figured typical for these batteries?
> >Also can anyone tell me what kind of resister I should use and what
> >figures I should see to test a 12v 6 or 7ah sealed lead acid battery.
> > Thanks!
> > -James Sutherland
> > email@example.com
> 27.45 is the right voltage but the current is very high. They should be
> consuming more like 1 to 10mA when they're fully charged. Did you leave
> the batteries discharged for a while? That makes them draw extra power
> and dry out while recharging.
> I just tested a 12V 7AH SLA and it settled to 5mA at 13.8V. It's a bit
> warm in here so I imagine it's normally more like 2mA.
Sealed batteries have numerous problems. Drying out is one of them, formation
of the bubbles that got stuck between the plates and can't escape is another.
Then they are real picky on charging current, overcharging and don't like deep
cycling. And low capacity, of course. Had similar problems - sealed batteries
didn't last long. So when I had enough of it, I just replaced my sealed battery
with a regular used boat battery that I placed next to UPS. Doesn't look
pretty, but works. Once in a while checking electrolyte level and density and
that's all for the maintenance. I think I have it for about 5 years now.
Then I also use a gadget called desulfatot. See:
http://www.flex.com/~kalepa/desulf.htm Easy to build and I use them it on my
boat batteries during winter storage also.
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