[time-nuts] UPS for my time rack
kd5byb at gmail.com
Sun Oct 11 09:16:54 EDT 2015
Good morning all,
On 10/10/2015 5:07 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> I was thinking of doing the same a while back, and intended getting a UPS
> and adding a large external battery pack, so if the mains failed late at
> night, I could run the GPS receiver and a few other things overnight, and
> consider starting the generator in the morning. I contacted a dealer on
> eBay, who specilaises in UPSs. He told me that the smaller units with built
> in batteries will die if you put large external batteries on them.
Years ago, I used to work at a place that would give me all their
cast-off computer parts, including old UPS'. I've taken probably opened
up about 20 of them, from various manufacturers.
The problem is that most don't have good heat-sinking on the power
transistors. One unit of a brand I can't remember, all it had for a
heat sink was an aluminum bar! Clearly, it was only designed to be run
for a small length of time.
(It's the same case for the transformers - on several removed
transformers, I've tried to use them backwards to get 12 VAC from 120
VAC, and they overheat quickly at more than 50% load.)
If you add external batteries, likely you will overheat and fry the
electronics as they get far hotter than they ever intended.
thanks much and 73,
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