[geeks] Memo to self: try not to destroy UPSs

[Kris Kirby]

Memo to self: Try not to destroy UPSs. It's really not a good idea to
"MacGyver" UPSs in the first place, but to use a fuse that is underrated
is almost as hazardous as to use one too large.

Background
---------

I took an older APC Smart-UPS 600 and ran #8 wires out the back to an
external battery pack which, for the time being, are cells of the exact
size that would normally be in the UPS. The #8 wires have an inline
automotive-style fuse holder holding a 20A fuse. Well, the fuse almost
melted into the holder, leaving a large hole in the bottom of the fuse
itself.

Fscking cool; that 600 held up about ~500W of load (at *least*). I smelled
the [plastic] burning and thought "SH*T! Lost another UPS!" UPS was fine;
the fuse had it.  24V x 20A = 480W.. oh yeah. :)

I'll get the pictures up soon; I just racked most of my machines
tonight. :-)

Power diagram (until failure ;-)

Utility ---> Smart-UPS 600 (Sine) ---> Belkin 525VA -------> Machine
                                   |                 \-----> Machine
                                   |-> Belkin 525VA -------> Machine
                                   |-> Belkin 525VA -------> Machine
                                   \-> APC Backups 300 ----> Ethernet
                                                       |     Bridge
                                                       \---> 100Mb/s
                                                             Switch

The Belkins and APC are square-wave. The Belkins also don't like to switch
under full load; they'd rather dump the load. :-(

-----
Kris Kirby, KE4AHR          | TGIFreeBSD... 'Nuff said.
<kris at nospam.catonic.net>   |    
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"Fate, it seems, is not without a sense of irony."