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Arthur Britto wrote: |
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> You likely want more than a minute. Most likely, you don't want your |
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> system to crash when coming back up when power fails soon after it is |
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> restored: your system could be in the middle of a fsck. Generally, you |
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> want enough capacity to: power off, power on, and then power off safely. |
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> |
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I second this. If the system is busy, it might take a couple of minutes |
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before it really shuts down. Ten to fifteen minutes is the MINIMUM |
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runtime I'd suggest. As the battery ages, runtime will lessen, plus it |
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gives you more room to expand. Power usage does not scale linearly, if |
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200 watt usage lasts X amount of time, 400 watt usage lasts less than |
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X/2 and 100 watt is more than 2X. My personal experiences with power |
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outages is that they're rare and short, but when they do occur they |
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happen a few times during the day/night. This, of course, may vary from |
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your area. Another thing to consider is brownouts or volt dropages. The |
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ups will kick in if the volt level drops too low (or too high). If this |
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happens frequently enough, it will deplete the battery or wear it out |
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much more quickly. |
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|
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> I am very happy with the CyberPower Intelligent LCD Series: CP*AVRLCD |
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> http://www.cyberpowersystems.com/ |
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> |
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> The series has: |
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> |
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> NUT support: |
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> You want something that works with NUT. Instead of a vendor specific |
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> package. This way your acquired skills are portable and future proofed. |
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> Network UPS Tools |
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> http://eu1.networkupstools.org |
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> NUT is great. It safely powers off my system when the UPS is low. |
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> Additionally, I set it up to e-mail my cell phone when the power state |
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> changes. If I go out during a power outage, I can stay out longer if I |
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> know the power is not restored. |
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My personal experience has been with APC equipment, but CyberPower is |
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also a great maker. I also second NUT. It's a better, more flexible |
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framework that supports just about any decent ups. |
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> |
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> USB interface: |
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> * A USB port is more future proof: serial ports are becoming rare. |
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> * Allows monitoring UPS state. |
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> * Allows powering off the UPS. |
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> |
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USB is almost mandatory now. Serial ports are usually only on high-end |
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expensive models, and (almost) never on what you'll find in stores. |
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> LCD Display: |
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> At a touch know: |
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> * power consumption (don't need to pull out a Kill-O-Watt) |
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> * battery charge |
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> * estimated minutes remaining |
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> |
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Before spending extra on anything with an LCD, google the model or lcd |
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errors first. I've seen reports that they tend to be inaccurate, |
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especially with APC. Mine under reports watt usage by a significant |
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amount, somewhere between 1/3 to 2/3 of actual usage(I forget what my |
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tests with various light bulbs showed). This was testing the ups with |
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only a small lamp plugged in, everything else UNPLUGGED (not just off). |
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I also used several light bulbs since they can vary a little. |
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> One thing to be wary of is like most inexpensive UPSes it does not |
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> provide a pure sine wave. This can damage a power supply that has |
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> active power factor correction. Luckily for my Silencer 750 Quad |
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> according to the manufacturer due to the short time in which the UPS is |
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> in use it is not an issue. |
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> |
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> -Arthur |
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> |
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> |
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|
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PaulNM |
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-- |
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