UPS batteries

He could always put them outside.

Sylvia.

[attributions elided]

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

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)

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!

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.

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.

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.

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).

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.

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.

Hi!

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.)

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.

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

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

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.

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.

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.

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.

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.

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'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

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.

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"...

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.

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.

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.

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! :>

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!

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.

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.

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)

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.

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!"

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 :> )

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