Sylvia Else wrote:
Both my old and my new SOLA UPS use a float voltage of 13.5 volts
(near enough), which is at the low end of the battery manufacturer's
recommendation (13.5 to 13.8). I get about three years out of
batteries in the old UPS. Too soon to say about the new one.

That takes care of one of the killer parameters - float voltage. But
at what rate do they recharge after a serious discharge?

I haven't checked that. My AVO meter apparently has a significant
voltage drop on its current range which messes up the result

I obtained an ammeter. On both UPSs the initial charge current is less
than one amp. The battery manufacturer's recommended maximum charge
current is more than two amps.

This is not that surprising. Providing a large charging current would
involve more expensive components, and provide limited real benefit.

I had argued that UPS manufacturers would err in favor of
faster charge times just to reduce the user's perceived
"exposure" *after* an outage. I.e., the available up-time
from the UPS shortly after an outage is obviously MUCH less
than the up-time available at the start of that immediately
previous outage (because the battery now has less reserves).
If a second outage followed the first before the battery
was able to recover substantial capacity, the user would
be disappointed in how "crappy" the UPS's performance was

Sure, the user would expect the UPS to be unable to maintain
the load for the full duration *shortly* after an outage...
but, how long does the user's acceptance of this reduced
capacity extend *after* such an outage? Surely, the next
*day* the user would expect the UPS to behave AS IF there
had never been a previous outage! But, how would they
feel about it 12 hours after the first outage? 6 hours? etc.

So the net result is that neither of my UPSs is using an excessive float
charge voltage, nor an excessive charge current, but I still only see
three years life out of the batteries.

grin I don't have much "sympathy" for you there! That's
sort of like complaining that you only had *two* dates for
the high school PROM... :-/

I think I've been lucky to get *perhaps* two years out of
batteries. Of course, that's reflecting the batteries that
I have discarded because the UPS "told me" they were bad
(idiot light) *plus* those that I was able to LEARN were
bad based on empirical evidence: they didn't hold up the load
when there *was* an outage!

I will be curious to see how life expectancy is affected by
NOT leaving the UPS's running unless their loads were also
"on"...