Posted by
Lynn W. Taylor, WB6UUT-2 on
Aug 31, 2017; 5:46pm
URL: http://elecraft.85.s1.nabble.com/Wattage-Draw-K3S-100-vs-KPA500-KAT500-for-UPS-tp7633842p7633910.html
I'm going to add that nearly every UPS made is meant to bridge the time
between when the power goes out, and the (automatic) generator starts.
If you don't have a generator, the UPS signals the computer(s) so that
they can shut down gracefully and turn the UPS off.
The (typically AGM lead-acid) batteries are sized for maybe 15 minutes,
which is way too fast. Drawing a lead-acid battery flat in 15 minutes
will kill it in only a few cycles.
What I did as part of my ISP was to remove the batteries from my UPSes
and replace 7 or 12Ah batteries with 100Ah batteries outside the case.
That didn't get me to the 10 hours for maximum battery life, but it got
me to 8 hours.....
Jim's suggestion also lets you size the battery to run all the gear for
more than a few minutes.
73 -- Lynn
On 8/30/2017 8:55 AM, Jim Brown wrote:
> A FAR better way to provide UPS for radio gear is a 12V deep discharge
> lead acid battery or 14.4V LiFePO4 that is float charged by a suitable
> power supply. And as has been discussed several times, LiFePO4 batteries
> have the major advantage that their operating voltage stays above 13V
> for most of their discharge curve, while lead-acid batteries are below
> 12V for most of their discharge curve. This system is as quiet as the
> power supply used to float-charge the battery.
>
> With either battery type, care must be taken to not overcharge the battery.
>
> 73, Jim K9YC
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