[mythtv-users] Uninterruptible Power Supply

David Brodbeck gull at gull.us
Wed Dec 23 23:19:12 UTC 2009

On Wed, December 23, 2009 6:31 am, Brian Wood wrote:
> On Wednesday 23 December 2009 07:15:41 am Dan Wilga wrote:
>> At 10:21 AM -0800 12/22/09, David Brodbeck wrote:
>> >Another good option, if you're moderately handy, is to find a local
>> >computer surplus outlet and buy "dead" UPSs.  I've picked up a few
>> >fairly nice APC BackUPS units from the "AS IS" pile for under $5
>> >each,  and they only needed new batteries.
>> I second this suggestion. Some APC UPSes will appear to be completely
>> dead, just because the batteries are no longer accepting a charge.
> Some UPSes use the same batteries that are used in emergency Exit signs,
> these
> are readily available and relatively cheap. Others use hard-to-find and
> expensive batteries. Sorry I don't have model numbers handy.

I have yet to find an APC UPS that didn't use readily available sealed
lead-acid batteries in one of a few standard sizes -- it's one of the
reasons I prefer them.  These are available at pretty reasonable prices
from places like Batteries Plus, Digi-Key, Mouser, etc.  The desktop-sized
units generally take either a single 12V battery or two 6V batteries in
series.  The ones that take two 6V batteries will also fit a single 12V
battery, if you rearrange the wiring harness a little.  Just pull out the
dead battery and order a new one with the same voltage and dimensions, and
you're good to go.

If you've got a server-type unit, it will still take standard batteries,
but it will take more of them, usually in multiples of four to make a 48V
pack.  If you find one of these you'll know it as soon as you try to move
it.  The 3 kVA rack-mount SmartUPS units we have at work have 40 pounds of
batteries in them.

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