UPS batteries

[Sylvia Else]

Michael A. Terrell wrote:

Thomas Tornblom wrote:
Meat Plow <meat@petitmorte.net> writes:

On Tue, 08 Dec 2009 23:32:19 +1100, Sylvia Else
sylvia@not.at.this.address>wrote:

Meat Plow wrote:
It was purchased around 2004
and last time I tested it in Oct it ran for an hour unplugged.
That's a long time for a UPS, and suggest's it's not heavily loaded. The
self test would be similarly undemanding.

The 350va powers a cable modem, two USB hard drives and a Linksys
network storage server 24/7/365.

The self test on the two 1000va units simulate a power failure
allowing them to run off battery power for 10 seconds or so. Enough
time for the unit to evaluate the state of the batteries according to
how it was designed. One 1000va unit provides power for a SA Explorer
HDTV cable DVR and a Panasonic 51" rear projector TV. The other
powers a 3 yr old desktop PC and 22" monitor and a 32" LCD HDTV.

I don't think you understand the principals of demand or load well
enough.
My APC SmartUPS 700 successfully ran selftests up until one of the
batteries failed and everything it supplied went down. :-(

It runs with a maximum load of 30%.

I have been contemplating using two full size 60Ah car batteries
externally instead of the small 7Ah internals.


Make sure you keep a couple fire extinguishers handy.

Such a modified UPS would clearly run for much longer, but given the run
time of a typical UPS on its standard batteries, I'd have thought any
heat sinks would be approaching thermal equilibrium, and wouldn't get
much hotter on an extended run.

Charging?

Sylvia.

 

[Sylvia Else]

D Yuniskis wrote:

Sylvia Else wrote:
Michael A. Terrell wrote:
Thomas Tornblom wrote:

[attributions elided]

I have been contemplating using two full size 60Ah car batteries
externally instead of the small 7Ah internals.

Make sure you keep a couple fire extinguishers handy.

Such a modified UPS would clearly run for much longer, but given the
run time of a typical UPS on its standard batteries, I'd have thought
any heat sinks would be approaching thermal equilibrium, and wouldn't
get much hotter on an extended run.

Charging?

I think the point was that lead acid car batteries produce H2.
Quite easy to ignite *in* a house :

He could always put them outside.

Sylvia.

 

[D Yuniskis]

Sylvia Else wrote:

Michael A. Terrell wrote:
Thomas Tornblom wrote:

[attributions elided]

I have been contemplating using two full size 60Ah car batteries
externally instead of the small 7Ah internals.

Make sure you keep a couple fire extinguishers handy.

Such a modified UPS would clearly run for much longer, but given the run
time of a typical UPS on its standard batteries, I'd have thought any
heat sinks would be approaching thermal equilibrium, and wouldn't get
much hotter on an extended run.

Charging?

I think the point was that lead acid car batteries produce H2.
Quite easy to ignite *in* a house :>

 

[D Yuniskis]

Sylvia Else wrote:

D Yuniskis wrote:
Sylvia Else wrote:
Michael A. Terrell wrote:
Thomas Tornblom wrote:

[attributions elided]

I have been contemplating using two full size 60Ah car batteries
externally instead of the small 7Ah internals.

Make sure you keep a couple fire extinguishers handy.

Such a modified UPS would clearly run for much longer, but given the
run time of a typical UPS on its standard batteries, I'd have thought
any heat sinks would be approaching thermal equilibrium, and wouldn't
get much hotter on an extended run.

Charging?

I think the point was that lead acid car batteries produce H2.
Quite easy to ignite *in* a house :

He could always put them outside.

Yes, this was the approach I was taking. But, for most smaller
UPS's you need 5 - 10X the desired output current from the
battery pack. So, the farther the batteries are located
from the actual UPS, the heavier the wire needs to be in order
to keep IR losses manageable.

And, the batteries are then subjected to the weather (temperature
extremes, etc)

 

[William Sommerwerck]

A quality UPS (not one of those cheap Chinese POS units)
will regularly exercise the batteries, running discharge/charge
cycles and measuring the results. Then the UPS will tell you
the condition of the batteries.

Compared to other types of cells, lead-acid cells are relatively "fragile".
(I once destroyed a $45 Sony battery pack by accidentally letting it run
down.) The /last/ thing you want to be doing with a lead-acid battery is
charging and discharging it to determine its capacity.

And what, pray tell, is going to happen if the AC goes out when the battery
is at the bottom end of the discharge-charge cycle? This is not unlike
punching a hole in life boat to test how quickly it will sink!

 

[William Sommerwerck]

Buying a UPS that is larger than you need will also improve
the lifetime of the unit and its batteries. The ratings provided
by the manufacturers are VERY optimistic and only result
in a few minutes of operation.

Remember to set the computer so that it'll shut down after a few minutes of
battery operation, should you not be around to turn it off manually.

 

[William Sommerwerck]

Some UPSs actually power the load continuously and are
recharging the battery from the AC line (like telco's operate).

Actually, /all/ UPSs work that way. The common type of unit -- which costs
less -- is properly called a Standby Power Supply (SPS). The circuitry
doesn't come on until power is lost.

 

[Sylvia Else]

William Sommerwerck wrote:

A quality UPS (not one of those cheap Chinese POS units)
will regularly exercise the batteries, running discharge/charge
cycles and measuring the results. Then the UPS will tell you
the condition of the batteries.

Compared to other types of cells, lead-acid cells are relatively "fragile".
(I once destroyed a $45 Sony battery pack by accidentally letting it run
down.) The /last/ thing you want to be doing with a lead-acid battery is
charging and discharging it to determine its capacity.

And what, pray tell, is going to happen if the AC goes out when the battery
is at the bottom end of the discharge-charge cycle? This is not unlike
punching a hole in life boat to test how quickly it will sink!

They're not running them down much. Just enough to determine the
batterys' health. Even this must certainly cause some aging, but it's
better than having batteries with no significant capacity on the day
that it's needed.

Sylvia.

 

[D Yuniskis]

William Sommerwerck wrote:

Some UPSs actually power the load continuously and are
recharging the battery from the AC line (like telco's operate).

Actually, /all/ UPSs work that way. The common type of unit -- which costs
less -- is properly called a Standby Power Supply (SPS). The circuitry
doesn't come on until power is lost.

Sorry, I wasn't clear:

"THE INVERTERS IN some UPS's actually power the load continuously
and are recharging the battery from the AC line (like telco's
operate)."

This is typically called an "online" UPS. Net current flowing
into/out of the battery is zero once charged. But, current
flowing into the *inverter* is directly proportional to the
load current being supplied EVEN WHEN AC POWER IS AVAILABLE.
I.e., these have zero transfer times. This is how the telco
CO's operate (in the US, at least) -- everything runs off battery
though those batteries are continuously being charged (replenished)

Cheaper UPS's, by comparison, are "offline" UPS's -- the
battery is charged from the mains "as needed" but the inverter
only supplies power to the load when AC power has failed.
Typically, a switch disconnects the load from the AC mains
and connects it to the inverter's output in this situation.
As such, there is a nonzero transfer time as the switch
flips from one "position" to the other. (note that this
switch is not present in the online UPS!)

Online UPS's provide isolation of the load from the mains.
As such, fluctuations in the mains (phase and or magnitude)
are insignificant (except to the extent that they hinder
charging of the battery). OTOH, the electronics are continually
stressed in these UPS's *and* the user sees an apparent increase
in power consumption as the inverter's (in)efficiency is *always*
reflected in the power drawn from the mains.

Loads serviced by offline UPS's are exposed to the mains
until the UPS decides otherwise. Since the UPS can only
detect problems with the mains after the fact, the only
remedy that the UPS has to a detected problem is to switch
the load to the inverter's output to bridge the "problem".
As such, it is impractical to handle cycle-at-a-time
problems on the mains.

In these scenarios, "line interactive" UPS's can be a win as
they allow the UPS's output to be adjusted *without* the
use of the inverter -- typically, by dynamically switching
the taps being used on an autotransformer in series between
the mains and the load (i.e., this only applies to operation
on the mains). For small-ish loads, these usually aren't
worth the added cost/weight (as most electronic devices
can usually adapt themselves to a wide range of mains
voltages).

 

[Thomas Tornblom]

D Yuniskis <not.going.to.be@seen.com> writes:

Sylvia Else wrote:
D Yuniskis wrote:
Sylvia Else wrote:
Michael A. Terrell wrote:
Thomas Tornblom wrote:

[attributions elided]

I have been contemplating using two full size 60Ah car batteries
externally instead of the small 7Ah internals.

Make sure you keep a couple fire extinguishers handy.

Such a modified UPS would clearly run for much longer, but given
the run time of a typical UPS on its standard batteries, I'd have
thought any heat sinks would be approaching thermal equilibrium,
and wouldn't get much hotter on an extended run.

Charging?

I think the point was that lead acid car batteries produce H2.
Quite easy to ignite *in* a house :
He could always put them outside.

Yes, this was the approach I was taking. But, for most smaller
UPS's you need 5 - 10X the desired output current from the
battery pack. So, the farther the batteries are located
from the actual UPS, the heavier the wire needs to be in order
to keep IR losses manageable.

And, the batteries are then subjected to the weather (temperature
extremes, etc)

Many batteries are available with venting hoses that can be used to
vent the gasses outside. Required in cars like my old audi, where the
battery is installed under the rear seat, in good VW tradition ;-)

I noticed that the SmartUPS can be SW configured with a number of
external battery packs. I configured the UPS to believe it had one and
two external battery packs, and by interpolating the run time it
showed with the various number of external batteries it appears that
they are nominally 20Ah. So a couple of 60Ah batteries would be
equivalent to three external battery packs, and would power my stuff
for over 5 hours.

 

[Sylvia Else]

Thomas Tornblom wrote:

D Yuniskis <not.going.to.be@seen.com> writes:

Sylvia Else wrote:
D Yuniskis wrote:
Sylvia Else wrote:
Michael A. Terrell wrote:
Thomas Tornblom wrote:
[attributions elided]

I have been contemplating using two full size 60Ah car batteries
externally instead of the small 7Ah internals.
Make sure you keep a couple fire extinguishers handy.
Such a modified UPS would clearly run for much longer, but given
the run time of a typical UPS on its standard batteries, I'd have
thought any heat sinks would be approaching thermal equilibrium,
and wouldn't get much hotter on an extended run.

Charging?
I think the point was that lead acid car batteries produce H2.
Quite easy to ignite *in* a house :
He could always put them outside.
Yes, this was the approach I was taking. But, for most smaller
UPS's you need 5 - 10X the desired output current from the
battery pack. So, the farther the batteries are located
from the actual UPS, the heavier the wire needs to be in order
to keep IR losses manageable.

And, the batteries are then subjected to the weather (temperature
extremes, etc)

Many batteries are available with venting hoses that can be used to
vent the gasses outside. Required in cars like my old audi, where the
battery is installed under the rear seat, in good VW tradition ;-)

I noticed that the SmartUPS can be SW configured with a number of
external battery packs. I configured the UPS to believe it had one and
two external battery packs, and by interpolating the run time it
showed with the various number of external batteries it appears that
they are nominally 20Ah. So a couple of 60Ah batteries would be
equivalent to three external battery packs, and would power my stuff
for over 5 hours.

Though it hardly sounds worthwhile unless you experience frequent
extended outages, or have mission critical systems running.

Sylvia.

 

[Sylvia Else]

Sylvia Else wrote:

who where wrote:
On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

who where wrote:
On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis
not.going.to.be@seen.com> wrote:

Hi,

I don't have anything other than "gut feel" to resort to
as evidence but it sure *seems* like most UPS designs
EAT batteries!

We rarely have outages here. So, there is no real
draw on the batteries in our UPS's. So, they should just
be on float charges.

Yet, the batteries seem to wear out far too frequently, IMO.

I could possibly understand regular outages cycling the
batteries too deeply.
That's not what kills most UPS batteries.

And, chargers too aggressively
replenishing them (after all, a UPS that quits because its
battery wasn't fully recharged earns a bad reputation for
its manufacturer).
That, but also an unreasonably high float voltage, is what kills them.
We've seen literally dozens of UPS' from assorted manufacturers with
failed batteries - baked dry, swollen, cracked cases. On fitting new
batteries and checking the charger behaviour, we note that the
recovery charge rate is definitely "too aggressive" (motive onvious)
and the eventual float charge voltage was definitely destined to kill
the cells within a year or so.

The only time we were happy that the cells were within the
manufacturer approved envelope was ... on DISCHARGE.

But, I can't see how even periodic
battery tests (performed by the UPS itself) could be the
problem -- unless there is something wrong with the
approach being used?

Can anyone with firsthand knowledge shed some light on this?
I.e., what *is* the UPS doing to/with the battery when it
is not being used to supply the load?
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

Sylvia.

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.

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.

Sylvia.

 

[Sylvia Else]

Sylvia Else wrote:

Sylvia Else wrote:
who where wrote:
On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

who where wrote:
On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis
not.going.to.be@seen.com> wrote:

Hi,

I don't have anything other than "gut feel" to resort to
as evidence but it sure *seems* like most UPS designs
EAT batteries!

We rarely have outages here. So, there is no real
draw on the batteries in our UPS's. So, they should just
be on float charges.

Yet, the batteries seem to wear out far too frequently, IMO.

I could possibly understand regular outages cycling the
batteries too deeply.
That's not what kills most UPS batteries.

And, chargers too aggressively
replenishing them (after all, a UPS that quits because its
battery wasn't fully recharged earns a bad reputation for
its manufacturer).
That, but also an unreasonably high float voltage, is what kills them.
We've seen literally dozens of UPS' from assorted manufacturers with
failed batteries - baked dry, swollen, cracked cases. On fitting new
batteries and checking the charger behaviour, we note that the
recovery charge rate is definitely "too aggressive" (motive onvious)
and the eventual float charge voltage was definitely destined to kill
the cells within a year or so.

The only time we were happy that the cells were within the
manufacturer approved envelope was ... on DISCHARGE.

But, I can't see how even periodic
battery tests (performed by the UPS itself) could be the
problem -- unless there is something wrong with the
approach being used?

Can anyone with firsthand knowledge shed some light on this?
I.e., what *is* the UPS doing to/with the battery when it
is not being used to supply the load?
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

Sylvia.

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.

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.

Sylvia.

I've measured the temperature in the battery compartment, and it's
showing about 10 degrees celsius above ambient.

Sylvia.

 

[William R. Walsh]

Hi!

IME, when the batteries are toast, you won't get *any* up-time
from the UPS.  Power goes... and so does the UPS!  :-/

I guess I consider them toast when the UPS still holds the load, it
just holds it for a few seconds or minutes--or it visibly struggles to
keep things going. (Meaning the output voltage sags to the point where
equipment won't work. Most don't do that, but some do.)

I've seen lots of UPS's discarded because they have killed
their battery packs.  Bulging battery cases, cracks, etc.

Most of the ones I see aren't that catastrophic. Perhaps that comes
from not realizing that they have failed and leaving them plugged in
for ages, presumably trying to charge batteries that simply cannot do
any more. Apart from a few Tripp-Lite units, the worst I've seen is
one or more cells that simply ran out of liquid. Very few units that I
come into contact with use gel-cell batteries.

In fact, the only one that I ever saw one that did was a really big
old Tripp-Lite monster that went "bang!" every time it powered on and
that put off an even bigger BANG and smoke when something inside blew
up.

Some UPS's actually power the load continuously and are
recharging the battery from the AC line (like telco's operate).
I would think this would be more stressful on the switching
power supply than the battery (as, essentially, the same current
is flowing into the battery as out)

I suppose it is, and that means the inverter itself must be built well
enough to stand a high load and constant operation.

I've also previously discarded a Back UPS 600 (?) as it used
a different physical size battery that was hard to come by
(since it didn't offer any feature that I didn't have on other
UPS's -- and, also had two pigtail power outlets on the
rear which always seemed like a kludge).

I have some similar units that got lawn tractor batteries as
replacements. By all indications they work fine.

I managed to blow up another larger UPS (3KVA... the size of
a dishwasher) by forgetting that power was still available
from the battery pack even though the AC mains were
disconnected... shorting a 120V battery into damn near anything
destroys the "anything"!  :< )

HeHeHe...and it probably puts off a nice bang, some ozone and "a bit"
of a spot weld on the shorting object--when and if it ever comes back
down to earth.

The biggest UPS that I've had personally was an ancient APC 1200VA
unit. It seemed to be pretty well protected with massive sand fuses
between the batteries and inverter, and large circuit breakers on the
output side. I once hooked it up to some car batteries (the biggest
ones I had sitting around) and abused it a little bit by hooking up a
moderately sized 110 volt room air conditioner.

It struggled to start the A/C but once it was running, everything was
fine. I just had to try it. More than once the UPS just gave up and
quietly shut down.

It still worked when I sent it off for recycling. I just didn't need
it and had nowhere to put the batteries. It hummed almost like a
microwave whenever it kicked on and had an impressive inverter inside
it.

All of my UPS's are connected to PC's or servers.  So, all feed
reactive loads.  Most are oversized for the loads they power.
Occasionally, I will run an extension cord from one of them to
power a CF light in another room if we have an outage at night.
(a "100 equivalent watt" CF runs for a LONG TIME on a small UPS!)

I ought to get that going again. I rigged up a very nice power outage
lighting system for my basement with an old APC UPS and a BIG gel cell
battery. (The battery got snaked from work after the Tripp Lite UPS
blew up. It was basically new and fit nothing else they had, so it was
either that or they would have trashed both of them.)

I should have used CFL bulbs at the time and didn't. I also never
added a relay to make the lights go on when power went off--they had
to be manually operated or on all the time.

All of the APCC devices have "replace battery" indicators.
All of them do a loaded test on power up (for about 2-3 seconds).

It's not a very good test and won't spot a faulty battery unless it is
REALLY bad. The particular 1200VA UPS I mentioned above would pass its
self test on the completely exhausted internal batteries every time.
Yet if you pulled the plug, it went down, not across.

I think all of the APCC designs use low voltage primaries.  E.g.,
12 or 24V.  I don't know if the battery abuse is consequential
to this (perhaps the charging circuits on the UPS's that I've
had that utilized 48V or 120V primaries were better designed
of necessity?)

That's what I've seen on the smaller models that come in capacities up
to 1500VA--which covers pretty much all the Back UPS series. These
also have modified sine wave inverters.

The bigger ones (Smart UPS 750XL and bigger) all seem to use 48 volt
battery arrangements (four twelve volt batteries) and most have true
sine wave inverters. They also have forced air cooling.

I've taken to powering the UPS's off when their loads are not
in use.

That really could only happen on a UPS where the load is supported by
the inverter all the time. If there is good line power on a
traditional line-interactive UPS (a relay closes and energizes the
inverter when the lights go out) it won't use the battery for
anything.

Most designs also charge the battery whenever they are plugged in. A
few (most notably the cheap APC "plugstrip" UPS units will *drain*
their battery even when turned "off" and unplugged. I guess this is
because the power switch is "soft" and doesn't shut the
microcontroller down.

(it also has the advantage of silencing the silly alarms that signal
in the event of a power outage -- if the UPS is on but its loads
are NOT, then I really don't want to be bothered by a chorus of half
a dozen little "chirpers"!)

Heh. I usually remove the beepers from the units I buy when I get
them. I don't want to hear them for any reason, and telling the
bundled control software to turn the speaker off usually won't make it
quiet all the time (it would still come on if the battery were nearly
depleted or bad) and you've got to install it.

So I just yank 'em with a quick touch from the desoldering iron.

I don't think it prudent to use regular lead acid batteries
("car batteries") in these applications unless the batteries
themselves could be located in a ventilated area -- I'd be
wary of outgassing.

I've done it and never had a problem. Any room that's decently
trafficked or serviced by an air handler (or furnace) should move
enough air to dissipate whatever gas might show up. I've also never
noticed the characteristic smell of the gas building up near the
batteries when they were in use.

However, I did take some precautions with the ones that I have here.
Most notably, they are in a breathable container with a lid and
openings that would be unlikely to spew nasty stuff even if the
battery went off.

To my knowledge, all lead acid batteries are vented somehow, so even
the ones that came in your UPS will release some gas if they have to.

William

 

[D Yuniskis]

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"...

 

[Sylvia Else]

D Yuniskis wrote:

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

Unless outages are that frequent, I wouldn't have thought that enough
users would experience this problem often enough for it to impact on the
manufacturer's reputation, particularly as anyone hearing the complaint
would tend to express the "what did you expect" response.

The extra cost of the components required to obviate this to some extent
would weight heavily on the manufacturer's mind.

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!

My "three" years is based on throwing them out when the UPS says they're
no good. As I've indicated, they're far from being dead at that point.

I should note that I don't usually run them down far during outages. My
philosophy is that if the power isn't back within a couple of minutes,
it's probably something that'll take longer to fix than the UPS can
handle, and the UPS is directed to turn off. This gives me time to save
work, etc, if I'm actually doing something at the time.

I don't think there's been an outage where the UPS got turned off, but
the power returned within the time that the UPS could have run.

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

It's far from clear that that's a good idea. Instead of a float charge,
you're exposing the batteries to self-discharge for a period, followed
by a higher chargin current for a while.

Sylvia.

 

[D Yuniskis]

Sylvia Else wrote:

D Yuniskis wrote:
Sylvia Else wrote:

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

Unless outages are that frequent, I wouldn't have thought that enough
users would experience this problem often enough for it to impact on the
manufacturer's reputation, particularly as anyone hearing the complaint
would tend to express the "what did you expect" response.

Dunno. As cynical as I am, I still find it hard to believe the
manufacturers are intentionally trying to cook batteries.
It's just not the sort of market where users will put up
with high maintenance costs -- I suspect most users discard
the UPS when the "battery breaks" and *probably* don't even
bother replacing the UPS (if they wouldn't bother with
replacing the battery, they probably wouldn't bother
replacing the entire UPS!).

Its sort of like "tape (or other) backup systems". Its the
sort of thing people *think* they should have -- until it
becomes too much of a nuisance. Then, they just learn
to live *without* it. So, by comparison, it wouldn't
make sense for tape backup manufacturers to design their
equipment to *prematurely* wear out the media. Its *not*
like toilet paper -- where you *have* to buy more when yours
runs out! :>

The extra cost of the components required to obviate this to some extent
would weight heavily on the manufacturer's mind.

Of course. And as they try to creep lower into the market
(to braoden their markets from the traditional "large
businesses" which originally saw needs for these things),
it only gets worse.

But, I think it costs nothing to float the battery at
the *proper* voltage. And, nothing to change the
charging algorithms ("its just software") to be more
gentle on the batteries.

I would *guess* that a UPS battery that lasted "a long
time" would be met with pleasant regard -- "Gee, that last
one lasted me 5 years... I guess I could pony up for
another one to get *another* five years!"

E.g., you get a car battery (in these parts) to last
five years and you are *literally* "tickled". Six
years has you downright giddy!

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!

My "three" years is based on throwing them out when the UPS says they're
no good. As I've indicated, they're far from being dead at that point.

I should note that I don't usually run them down far during outages. My
philosophy is that if the power isn't back within a couple of minutes,
it's probably something that'll take longer to fix than the UPS can
handle, and the UPS is directed to turn off. This gives me time to save
work, etc, if I'm actually doing something at the time.

I have found them most useful in handling things like
"switching transients" and other momentary outages
("Hey, did the lights just blink in here?") that are
*just* long enough to cause a PC (or some piece of
peripheral kit) to reset. I wouldn't think of running
under UPS operation -- it would be just too damn stressful
("I wonder how much longer the power will be out? I wonder
how much longer the UPS will last? I wonder how much longer
this 3D render will take???")

OTOH, if you are in the middle of typing a line of code
and power fails, its usually *really* hard to remember
what you were working on at that instant! And, no way
to recover exactly that.

I don't think there's been an outage where the UPS got turned off, but
the power returned within the time that the UPS could have run.

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

It's far from clear that that's a good idea. Instead of a float charge,
you're exposing the batteries to self-discharge for a period, followed
by a higher chargin current for a while.

These are PC's. They see use every day. The battery sits
for 12 hours "self discharging" then gets floated for the
next 12 hours. I suspect the effect can't be any worse
than floating it "too hot" for the 24 continuous hours.

<shrug> As I said, I will see how this affects battery
life. If I find myself tossing out batteries just as
often, then I'm no worse for the wear (and, I will have
saved the energy being dissipated in the UPS while the
*loads* were switched off)

 

[Sylvia Else]

D Yuniskis wrote:

Dunno. As cynical as I am, I still find it hard to believe the
manufacturers are intentionally trying to cook batteries.

Particularly if their users do as I do, and just buy an equivalent SLA
from their local electronics shop, rather than going back to the
manufacture of the UPS.

I've noticed that my new UPS, which I originally though has a custom
pack actually has a battery pack which is just two standard 7.2Ah SLA's
separated by some foam plastic, and stuck together with tape. Maybe they
hope that that way they'll make more sales of replacement batteries. Not
from me, they won't.

Sylvia.

 

[D Yuniskis]

Sylvia Else wrote:

D Yuniskis wrote:

Dunno. As cynical as I am, I still find it hard to believe the
manufacturers are intentionally trying to cook batteries.

Particularly if their users do as I do, and just buy an equivalent SLA
from their local electronics shop, rather than going back to the
manufacture of the UPS.

I think for corporate users this is probably the case -- most
"employees" have no real incentive to save their boss' money :<

And, for The Clueless users, they have no idea and would, at
best, drag the whole UPS to the local "Batteries R Us" store
(and pay the same price that they would had they gone to the
manufacturer direct).

I think the latter case is where lots of UPS's get discarded:
"Whew! I only paid $X for the thing and they want $Y just
to replace the battery!"

I've noticed that my new UPS, which I originally though has a custom
pack actually has a battery pack which is just two standard 7.2Ah SLA's
separated by some foam plastic, and stuck together with tape. Maybe they
hope that that way they'll make more sales of replacement batteries. Not
from me, they won't.

Yes, that is true of almost every UPS I've come across.
Standard size batteries gimmicked together in some way
that makes it "easy" for the user to replace the entire
assembly "as a block".

Usually, a (disposable) fuse in series somewhere. I have
seen the fuses used as the "wire" to connect two series
batteries together as well.

Since most standard batteries use fastons, it is easy to
pull the harness off the batteries and use it to "build"
another battery pack. Unfortunately, the connectors that
these battery pack assemblies often use to mate to the
UPS itself tend to be a lot harder to acquire (i.e., don't
ever lose the harness if you want to keep the UPS!). I
have one such UPS in need of a harness, currently. If I
stumble upon a spare, fine. Otherwise, the UPS isn't worth
the cost of buying a new harness (which would probably
only be sold with the batteries attached :> )

 

[William Sommerwerck]

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.

In the Seattle area, an outage is often followed by a restoration, than a
second outage. I've learned to wait to reboot.