Guide to Choosing a UPS

(AKA Battery Backup)

By Joshua Erdman
Digital Foundation, inc.

Before we go into a review of UPSes you should brush up on some power protection terms and devices. These can be found in the article: Guide to Power Protection.

This review covers the features, pricing, and UPS models made by APC, PowerWare, and Oneac.

A UPS will usually fall into one of three protection levels:

Level 1 - This is a UPS that just switches over to battery when the power goes out. They also provide surge suppression against power spikes and battery management to prevent overcharging.
Level 2 - These UPSes provide protection against Brownouts and Blackouts without having to switch to Battery Power.
Level 3 - Includes power conditioning via double line conversion for complete isolation against line noise and sine wave distortion. These are designed for mission critical applications. Also includes some form of Line Conditioning.

Product comparisons for UPSes at Levels 1 and 2 will be rated as close as possible to a minimum of 650VA. Level 3 will be for products rated at 1300VA. All versions will be the non-rack type as to keep price comparisons on the same level.

Level 1 UPSes

	APC	PowerWare	Oneac
Model	Back-UPS	PW3110	N/A
Part #	BK650MC	PW3110 700
Communication Port	Serial	N/A
Rating	650VA	700VA
Est. Runtime @ 50% utilization	21 min.	13 min.
Retail Cost	$130	$145

If you are really looking to save pennies and want the cheaper UPS, the choice is clear, the APC UPS is by far the best. It is much cheaper than the other, comes with communication capabilities and a superior runtime.

Level 2 UPSes

	APC		PowerWare	Oneac
Model	Back-UPS Pro	Smart-UPS	PW5115	Desk Power
Part #	BP650S	SU700NET	PW5115 750	DP650A-DB
Data Port	Serial	Serial	Serial	USB/Ser.
Rating	650VA	700VA	750VA	650VA
Est. Runtime @ 50% utilization	20 min.	20 min.	14 min.	8 min.
Line Conditioning	No	Yes	Yes	Yes
Other Accessories	No	Smartslot
Retail Cost	$300	$320	$410	$240

All UPSes in this category include surge suppression and only the Back-UPS Pro doesn't have Power Conditioning capabilities.

My choice is the APC Smart-UPS 700. Even though it is not the cheapest of them all, it has the run time. With the Smartslot expandability you can add extra serial ports, UPS network management, or even a 5-port hub.

If you are looking for a UPS with the capabilities above but have 220V outputs, look at the APC Matrix. They are not ranked in level 3 because they lack double line conversion power conditioning.

Level 3 UPSes

	APC	PowerWare	Oneac
Model	SmartUPS	PW9120	ON Series e
Part #	SUA750XL	PW9120 700	ON600
Communication Port	Serial/USB	Serial	Serial/USB
Rating	750VA	700VA	600VA
Est. Runtime @ 50% utilization	35 min.	18 min.	27 min.
Expandable	Yes	Yes	Yes
Retail Cost	$419	$630	$745

Based on the specs, APC takes the cake. If you are looking for uptime for mission critical equipment the expandability is really an important feature. Also make sure the management software integrates well with your network. A UPS is of little help for mission critical equipment if the software cannot safely shut the servers down gracefully before the batteries die.

Article last reviewed: 11/05/2005

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Created by: Digital Foundation, inc.

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