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From: firstname.lastname@example.org (Bob Wilson)
Subject: Re: UPS - Sealed lead acid battery.
Date: Sun, 06 Oct 2002 05:18:24 -0000
Organization: Your Organization
X-Newsreader: WinVN 0.99.9 (Released Version) (x86 32bit)
In article , email@example.com
>"Kevin McMurtrie" wrote in message
>> In article <firstname.lastname@example.org>,
>> email@example.com (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
>> > firstname.lastname@example.org
>> 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,
>of the bubbles that got stuck between the plates and can't escape is
>Then they are real picky on charging current, overcharging and don't like
>cycling. And low capacity, of course. Had similar problems - sealed
>didn't last long. So when I had enough of it, I just replaced my sealed
>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
>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
>boat batteries during winter storage also.
Before you tar all sealed batteries with one brush, so to speak, it would be
wise to ask what KIND of sealed battery they are in the first place!
Calcium-alloyed "flooded" lead cells are one type of "sealed" cell (albeit
not all that well sealed, since they often have a means of adding more water
if eventually needed). Valve regulated lead acid cells are a second distinct
type of sealed cell. Finally, gelled electrolyte lead acid cells are a third
All three of the above types require significantly different charging and
float characteristics. For example, charging a valve regulated battery using
criteria for a gelled electrolyte cell will result in damage to the cell.
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