What to look for when buying a UPS

[Jon Smark]

I'm looking for a UPS to protect by fresh FreeNAS build. I've never owned a UPS before, so I'm not familiar with caveats and tradeoffs associated with this purchase. Anyway, I've heard good things about APC in this forum and others, and since I can source them locally it seems like a good choice. I have a few questions, though:

• For a given power, they have models in tower and block format. The latter's battery can be replaced by the user. Is this something worth having, or do batteries last such a long time in normal conditions that the UPS is likely to fail for other reasons before one needs to replace the battery?
• In the models without user-serviceable battery, is the battery still a discrete unit which can be replaced by the vendor's representative?
  
• I checked the NUT compatibility database, but it only says how the driver was derived, not the level of support. Is the APC Back-UPS line (not Pro) well supported in FreeNAS Corral?
• How much headroom should I plan for the power output? Suppose my system consumes 350W max. Would a 400W output be enough?

 

[gpsguy]

All the UPS's I've had, have user replaceable batteries. Here at home, I have both types that you describe. How long do the batteries last - maybe 4 years or so.

I've rarely seen the electronics in a UPS fail. Often times you find a UPS with a dead battery, for sale at a cheap price. Given how much a battery costs, especially for what you call the "block format", users often buy a new UPS, rather than buying a new battery for their old UPS.

APC has a "UPS Selector" tool to help you with sizing. See - http://www.apc.com/us/en/tools/ups_selector/home/load

For a given power, they have models in tower and block format. The latter's battery can be replaced by the user. Is this something worth having, or do batteries last such a long time in normal conditions that the UPS is likely to fail for other reasons before one needs to replace the battery?