06-29-2011 10:30 PM
07-20-2011 08:51 PM
... one has to wonder what possible application a used/recycled APC UPS could possibly have, considering their rather low initial pricing ...
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: Open Mailbox
09-19-2011 02:50 AM
While this is a late reply, I suppose someone might be interested in this.
Why would you want old APC UPS's? Here's a few reasons:
1. Failed unit. If you have a failed unit with good batteries, you can just swap the pack in to most any APC of comparible size and it'll work. Remember, they just use 12V gel-cell packs.
2. Custom-UPS. While only really doable with the larger units(and older ones), you can take one or two car batteries(or lawn & garden ones, depending), and hook them up. So long as you remember to use two in series for the 24V units, and one for the 12V units, they will work perfectly fine, and have several times as long a backup time.
Now, there are two problems with this: A, on smaller units, they have no ventalation(or not enough) and will overheat at high loads about the time the stock battery runs out. So, you either have to setup a custom vent solution, or use it way under spec(say for running a couple of lights).
B, if you use *too* big a battery on too small a UPS, the charging circuit may not be enough to keep it charged, or, more likely, not be able to recharge it in a reasonable amount of time. If this is the case, you may have to setup a custom charger on the battery bank.
Now, of course, in theory, you also have to worry about outgassing during charging, but in practicality, you don't really, so long as you have *some* ventalition to your batteries - Most modern batteries have "recombining caps" which do a very good job of taking the electrolysed hydrogen and oxygen and combining them back into water which drips back into the cell. This also helps to reduce the amount of water you need to add.
Also, the rate of charging on these UPS's is extremely slow, which also helps.
(Note: set one of these up a while back with two lawn and garden batteries; worked great once I got the two batteries charged and equalized)
3. Spare parts. Self explanitory.
4. Scrap. While mainly a subcategory of the above, if you find old UPS's(1990s vintage mainly), they all use the old powertransistor switching 12v at 60hz -> hefty transformer(as opposed to the more modern FET switching 12V at several KHZ -> small transformer/inductor -> rectifier to 170VDC -> high-voltage FET switching at 60hz), and those hefty transformers are *full* of copper, which is worth a fair bit these days.