Time to buy a UPS (Uninterrupted Power Supply) Suggestions?

[turbodog]

Buy you a used APC unit off ebay. These things last forever.

 

[Marty Weiner]

There's plenty of used UPS' on Ebay. New batteries are about $15 plus shipping but there is a new technology twist called AVR (Automatic Voltage Regulation).

It covers brownouts and blackouts by raising the reduced voltage to a usable level.

Anybody have any thoughts (pro or con) on these units?

 

[turbodog]

The avr is a nice feature. If a high/low voltage condition exists it will correct it (up to a point) without going to the battery.

It will help prolong battery life IF you are subject to these outages.

Another way to prolong battery life is to set the ups to shutdown at the start of the outage, not just when the battery is exhausted.

Most people don't know it... but CERTAIN models of APC UPSes will shutdown the pc, then shutdown the ups itself. This keeps it from continuing to drain the battery. These units will then require the battery to be charged to a certain level before turning on. This allows time for an orderly shutdown if an outage were to happen just as the pc turns back on. But, these are features of the smart series. They may or may not be available on normal backups series.

Fyi, the smart series also outputs pure sine wave power. This is not a big deal, just a bonus.

 

[turbodog]

I would look very hard at this model.

http://cgi.ebay.com/APC-Smart-UPS-7...ryZ44963QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The batteries are cheap for it. There are no fans to go bad.

 

[turbodog]

The apc smart ups 700 is a nice unit. I've got it and a smart ups 1100 also. It's the smallest of the smart series.

The battery slides out the front and is easy to replace.

Apc's web site for this model:

http://www.apcc.com/resource/include/techspec_index.cfm?base_sku=SU700NET&language=en&LOCAL.APCCountryCode=WW=en&LOCAL.APCCountryCode=WW[/url]

 

[turbodog]

Be aware the the interface to upses can be usb or serial. And some models have had a mid-year changeover. Some models can take either also.

Be sure that the unit comes with the cable, unless you want to track one down later.

Win xp will manage the unit pretty well, but the mfg software does a better job. Most mfgs will allow a download of the software for free.

 

[Marty Weiner]

The apc smart ups 700 is a nice unit. I've got it and a smart ups 1100 also. It's the smallest of the smart series.

The battery slides out the front and is easy to replace.

Apc's web site for this model:

http://www.apcc.com/resource/include/techspec_index.cfm?base_sku=SU700NET&language=en&LOCAL.APCCountryCode=WW=en&LOCAL.APCCountryCode=WW[/url]

I haven't even looked at the APC line but it looks interesting. For a new unit, I like the compact Tripp-Lite AVR550U but am keeping an open mind. New, they are only aobut $55 plus shipping.

 

[turbodog]

But coming back to avr. I live in MS and we have plenty of electricity as opposed to like CA. I've seen my avr kick in 4-5 times in 10 years. And usually it was for a power problem that was soon fixed by the electric company.

But in real life... it will help battery life.

 

[turbodog]

Several mfgs have been making these 'compact' units lately. They are nice on features, but HORRIBLE on battery longevity.

But, they ARE cheap. Hmmm.....

I actually threw away 2 of these the other day. One was brand new.

Be aware that VA is not WATTS. Usually apc units are rated where watts are 60-65% of the va rating. Cheaper units are rated at 50%. More is better. Look farther down the page to this "550VA / 300 watt power handling ability". That's 55%. That' better than some.

Here is apc's equivalent unit. http://www.apc.com/resource/include/techspec_index.cfm?base_sku=BE550R

330 watts/550va = 60%
$59.99 retail


But all of these units are horrible on battery life. A better, larger unit will have MUCH, MUCH longer battery life. You will probably spend less overall $ in a 2-3 yr period with a better unit.

And a unit with a weak battery will not allow enough time to shutdown your pc properly. This is especially true for a small unit. Their runtimes (the tripp-lite and apc models above) are 3.3 minutes at full load.

By the way, the smart ups 700 has been replaced with this. http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SUA750

It takes serial or usb interface cables. But, I don't see any "super" deal on ebay.

I would buy the older model and make sure I had a serial port.

 

[turbodog]

Keep this in mind.

THESE UNITS LAST FOREVER.

The model you buy today will very likely still be working perfectly 10 years down the road.

 

[gadget_lover]

I have to take exception to the "lasts forever" claim. As the battery ages or is abused by power failures, the cells tend to eventually short or go open. The batteries tend to swell, and (very seldom) leak a little gel. The unit heats up, which is deadly for electronics over long periods.

Yes, you can add a new battery and quite likly revive it, but many units are designed to be disposable. I have 9 UPSes around the house. I have 4 dead batteries currently waiting to go to the recyler. I have replaced teh batteries in most of them at least once.

The $15 batteries that were mentioned are almost certainly NOT deep discharge. When a power failure hits the average UPS runs til the battery goes dead, and that may be pretty quick. A typical SLA will die after only a few (3 in one case) power failures because fo this abuse.

The bigger the battery capacity and better quality the battery (AGM are better than a plain SLA) the more power failures it will survive. I have a 1250va powering my workstation + monitor, and it's only pulling about 400 watts. It's set to shutdown after 5 minutes, or 20% discharge. The UPS runing my network equipment is set to run much longer since the load is only a few hundred watts.

I really need to get all of it running on a 48 volt battery bank liek the phone company uses.

Daniel

 

[bfg9000]

Actually, none of the OEM batteries are deep discharge either--those cheap Yuasa batteries were used as original equipment by every brand. And while you could probably get an AGM Deka battery in a close enough size to fit, the charging algorithms in those UPSes are probably all wrong for AGM. But by vastly oversizing the UPS, you can probably avoid most deep discharges in the first place.

AVR is not a new thing; APC called it SmartBoost and SmartTrim in the early '90s. I am still using some of the smallest Smart-UPS APC models: the under-monitor 250 and 400 models. Those were built in 1993 and have SmartBoost AVR and the sine-wave output important for electric motors. I've replaced the batteries just once.

Which goes to show, buying a used server-grade UPS (that sold for hundreds or thousands when new) for a couple bucks and replacing all the batteries gets you a far better UPS than spending more for a new cheapo consumer model. I mean I hope you don't throw the old Surefire away just because the batteries are dead and you can buy a new Mag with batteries for $12.

 

[Myself]

I'm with bfg9000 on this one: Go oversized, the longer runtime is nice. Because of Peukert's phenomenon, batteries run at half the drain will give you more than twice the runtime: you're burning less power in the batteries' internal resistance, so more ends up in the load. At some point the background draw of the UPS's own circuitry cancels out the gain, but you'd have to be running a 5-watt nightlight or something.

Set the software to shut down your PC fairly early, if you're not there and the UPS kicks in. What's the point in having the PC sit idle for another 15 minutes, killing the batteries, before shutting down? 2 or 3 minutes is plenty to see if the power's going to come back on, then just hibernate the sucker and call it a day. No sense toasting your batteries if you're not even there. If you're at the console, 15 extra minutes to finish your work will be real nice.

Oh yes, don't try to parallel a bunch of car batteries with the UPS's internal battery. Because of differences in chemistry between lead-acid, lead-calcium, AGM, and so on, you end up with slightly different voltages. Mixing chemistries in a parallel string can lead to the higher-voltage batteries dumping their power into the lowest-voltage one, which goes into thermal runaway and explodes. That would be bad. Even within the same chemistry, batteries of different ages or makes shouldn't be mixed in a parallel string.

 

[Handlobraesing]

I'm with bfg9000 on this one: Go oversized, the longer runtime is nice. Because of Peukert's phenomenon, batteries run at half the drain will give you more than twice the runtime:

This entirely depends on how heavily the battery pack is loaded. Going oversize is a good advise, but I think watts per battery V*A is a better gauge, since the unit's capacity only represent the inverter's capability.

Today's units have a very high watts per battery V*A ratio, so you have to usually oversize by a factor of two to get a decent battery life.

Smart-UPS 700VA(600W) XL has the same battery as a Smart-UPS 1500, a 25 lbs 24V 17Ah pack. The half load vs. full load runtime ratio of 3 (51 minutes @ 300W, 17 min at 600W). At maximum load, you have 1.47W per battery V*A.

BackUPS LS 700 410W has a 12v 9Ah battery and 11.1min @ 50%, 2.1@100% or ratio of 5.29(ideal is 2).

You have 3.8W per battery V*A, so the batteries are pushed a lot harder. With the battery loaded this heavily, you'll get reduced runtime at lower load as the battery age, but it simply won't handle the max load the UPS is capable of and cause it to cut off instantly. If you get one with lower watts per battery V*A ratio, the runtime will decrease with age, but you will get more years from the battery pack before the performance of battery becomes unacceptable.

I have to take exception to the "lasts forever" claim. As the battery ages or is abused by power failures, the cells tend to eventually short or go open. The batteries tend to swell, and (very seldom) leak a little gel. The unit heats up, which is deadly for electronics over long periods.

If taken care of, battery can last five years. If abused, it's done in a month. The worst thing you can do is let it store unused without letting it charge every few months or not charging it completely. Left discharged, lead acid battery is quickly destroyed.

Yes, you can add a new battery and quite likly revive it, but many units are designed to be disposable. I have 9 UPSes around the house. I have 4 dead batteries currently waiting to go to the recyler. I have replaced teh batteries in most of them at least once.

This is true for newer ones with the outlets and the top cover made of single piece molded plastic screwed onto plastic half. Smart-UPSs and older Back UPSs have a metal chassis and the outlets are of same Duplex type used on regular wall outlets, not contacts embedded into chassis.

The $15 batteries that were mentioned are almost certainly NOT deep discharge. When a power failure hits the average UPS runs til the battery goes dead, and that may be pretty quick. A typical SLA will die after only a few (3 in one case) power failures because fo this abuse.

The bigger the battery capacity and better quality the battery (AGM are better than a plain SLA) the more power failures it will survive. I have a 1250va powering my workstation + monitor, and it's only pulling about 400 watts. It's set to shutdown after 5 minutes, or 20% discharge. The UPS runing my network equipment is set to run much longer since the load is only a few hundred watts.

I really need to get all of it running on a 48 volt battery bank liek the phone company uses.

Daniel

APC Smart UPS XL series or any of the medium tower (the one that weighs 50 lbs) APC UPS is looking good.

 

[KC2IXE]

RE "oversized batteries"
Batteries are rated in "watthours" - the ability to deliver 1 watt for 1 hour, only it's a BIT of a lie. You can't draw 1 watt for 1 hour from a 1 watthour battery

Batteries (depending on chemistry) are rated at a discharge rate of either C/10 or C/20 - usually C/20 (where C is the watthour capacity of the battery) - for lead acid gel cells, figure C/20 - any faster than that, you get 1)Less capacity, and 2)you have a risk of damaging the batteries

 

[Handlobraesing]

RE "oversized batteries"
Batteries are rated in "watthours" - the ability to deliver 1 watt for 1 hour, only it's a BIT of a lie. You can't draw 1 watt for 1 hour from a 1 watthour battery

They have many different ways of rating batteries. Ah, Reserve Capacity, CCA, Watts @ 15 minute,etc.
I found one rated as:
120W @ 15 minute-rate to 1.67V per cell @ 25°C (77°F)

Batteries (depending on chemistry) are rated at a discharge rate of either C/10 or C/20 - usually C/20 (where C is the watthour capacity of the battery) - for lead acid gel cells, figure C/20 - any faster than that, you get 1)Less capacity, and 2)you have a risk of damaging the batteries

NiMH and NiCd are usually rated at C/5
Lead acid at C/20

Maximum current is a separate spec. C is not the watt hour capacity. C is the Ah capacity.

 

[TedTheLed]

another point we forgot to mention was the start-up current demand spike of your system. a modified sine wave (msw) inverter won't have much power or headroom above it's rated power. For more headroom, and much more efficient operation (= longer runtime from same battery) use a ('pure') sine wave inverter, they are more money but in my opinion are worth it, especially for running electronic devices..a msw unit can and will burn out certain devices, the Waring Commercial Digital Timer will burn out at high wattages using a msw, but works fine with a sw, for instance..

(Do the triplite and other relatively inexpensive UPS units use sine or mod-sine?
I see Prosine has a 1000 watt sinewave model with a transfer switch, but it's 600 +-$$..

 

[KC2IXE]

...snip...
Maximum current is a separate spec. C is not the watt hour capacity. C is the Ah capacity.

Your right - drugs, even prescription ones - do bad things to the mind

 

[TedTheLed]

just to be clear, the 'current spike' (or wattage spike if you prefer) I spoke of was referring to the high current demand upon turn on of your equipment..

-------

a 10 amp
hour battery will give you 10 amps for an hour (more or less)
and/or 120 watts (if it's a 12 volt battery) for an hour (more or less)
(and damage your battery a bit)

divide either by half (or a fifth or whatever) and you re talking about the same amount of energy.. ie.; 5 amphours = 120 watts for 1/2 hour.

of course it's not good to take more than about half of a battery's capacity at a time, less is better.

 

[Fallingwater]

Interesting articles about UPSes:

http://www.dansdata.com/diyups.htm
http://www.dansdata.com/upsupgrade.htm
http://www.dansdata.com/sbs9.htm