[TriLUG] recommendations for UPS 12V batteries?

[Wes Garrison via TriLUG]

Through my (limited) knowledge of these things, a higher float voltage over
long time periods does much more damage to battery longevity than a higher
charge voltage for most applications where you discharge relatively
infrequently but are constantly applying float charge.

I've been using a nice Tripp-Lite 48V Inverter with expensive 150AH AGM
batteries for 4 years, and the slightly higher float voltage killed the
batteries after just 4 years instead of the expected 10+.
Here's the inverter:
https://tripplite.com/2400w-powerverter-aps-48vdc-120v-inverter-charger-auto-transfer-switching-hardwired-ul~APS2448UL


It's a "square-wave", not a true sine-wave, but my computer equipment
doesn't care.

The batteries call for float voltage of 54V - 55.2V, and the charger
supplied 54.4V (so it claims; I didn't measure), so technically on the low
side of the acceptable range, but still high enough to cause an early death.

I now have new 60AH AGM batteries (much cheaper) running with the same
inverter but using an external charger specifically configured for AGM
instead of a more generic "gel" setting.

We'll see how much longer they last...
_________________________________
Wesley S. Garrison
Network Engineer
Xitech Communications, Inc.
phone:  (919) 260-0803
fax:       (919) 932-5051
__________________________________
"Lead us not into temptation, but deliver us from email."


On Thu, Apr 23, 2020 at 2:15 PM Joseph Mack NA3T via TriLUG <
trilug at trilug.org> wrote:

> On Sat, 18 Apr 2020, Pete Soper via TriLUG wrote:
>
> > Yars ago I instrumented a couple UPS devices to see how the behaved. I
> recall
> > one that was in the wrong county with respect to float voltage. Too low
> and
> > the electrodes accumulate sulphate and die. Too high and the water is
> > disassociated and driven past the pressure release as gas, leaving the
> > electrolyte short of ions. And the float voltage needs to be temperature
> > compensated.
>
> I took out my two APC 700s, in which the batteries only last 2 years.
>
> They have two batteries in series.
>
> On float, one had the batteries at 14.0V and the other at 13.8V. I would
> accept
> anything between 13.8 and 14.4V. I was pleasantly surprised that both
> batteries
> within each UPS had the same voltage within 0.05V (If one goes low, then I
> assume the charger will hammer the other one.) The batteries weren't warm,
> so I
> assume the UPS is being nice to them.
>
> So it would seem that these two APC UPS is doing the right thing as far as
> the
> batteries are concerned.
>
> I then took out my unit in which the batteries lasted 10 years.
>
> It has float V=55.0 (4 batteries in a bank. I didn't open it to measure
> each
> battery) = 13.75V/battery.
>
> It would be interesting if a difference in float V of 0.1-0.2V/battery was
> making all the difference.
>
> Joe
>
> --
> Joseph Mack NA3T EME(B,D), FM05lw North Carolina
> jmack (at) wm7d (dot) net - azimuthal equidistant
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