[time-nuts] UPS for my time rack
Ben Hall
kd5byb at gmail.com
Sun Oct 11 13:16:54 UTC 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,
ben, kd5byb
More information about the Time-nuts_lists.febo.com
mailing list