At 10:02 AM 5/21/2003 -0400, you wrote:
> I've ordered an Orion and for the first time will be
>using an outboard DC supply (a used Astron RS-35M
>is on the way). I often get short power glitches since I am
>in a rural location and am concerned about getting resets
>on Orion since I understand it takes awhile to reboot (how
>long?) I'm thinking of getting a small battery (motorcycle)
>to place between the RS-35M and Orion. This would stay
>fully charged and might help prevent unwanted resets by
>brief power glitches.
>
> Has anyone ever done anything like this?
I go one step further, but I'll save that for the moment...
I would recommend going with a small gel-cell battery. You can
find 7-25 amp-hour batteries used from people who maintain life-
critical equipment for reasonable prices ($5-$30). Then you can
use a battery charger -- *NOT* a power supply -- to keep the battery
at full charge (float level).
The reason to use a gel-cell over a wet-cell is that wet-cells produce
a very fine mist of electrolyte when charging. You *really* don't want
sulfuric acid mist around your shack, any more than you would want salt
spray there.
Another reason is that if you knock it over, it doesn't matter. If you
do that with a wet cell, again you have to worry about sulfuric acid
effects on your floor.
The reason to use a charger instead of a power supply is that the charger
will detect the amount of current needed to keep the charge even and
deliver it cleanly. Better ones will compensate for the temperature.
For gel-cells, there are two types of charge, bulk and float. (Wet
cells also have an equalize charge.) Your power supply will either
charge inefficiently or overcharge, and you only overcharge a gel-cell
once before it is destroyed.
> Is it even
>necessary or is there enough residual energy in the PS
>filter caps that brief interruptions (typically <10 sec) are not
>a problem?
Filter caps won't hold that long. You can handle the droops with a VERY
LARGE capacitor bank, but very large capacitor banks have their own problems,
including safety, initial charge, and surges. (Do you really want to see
what a 10 Farad capacitor bank does with a dead short?)
> I don't really want to buy a UPS large enough
>to power Orion but is there a simpler solution?
No, buying a charger to charge batteries to run an inverter to run a power
supply is not the most efficient way to go... :-)
You could do what I suggested. If you want to put the battery outside,
you could use a marine or other deep-cycle wet-cell battery in a battery
box, charging from your power supply through a low resistance high-wattage
resistor for current limiting purposes.
I went all out. Since the western power grid collapse in the mid 90s,
I run entirely solar for my ham gear and receivers, and have a 1.1kW
sine-wave inverter with transfer switch that the computer gear fails
over to. (Items like the RX-340 are plugged into the inverter directly
and are never inflicted with mains power.) I bought 8 25 A-H gel-cells
for $11 each and 1 50 A-H absorbed-glass-mat cell for $20 which provide
power for the inverters and the 12 V rigs. A battery balancer/power
supply provides 24 V to the 24-28 V rigs. The system was built slowly
over time, a couple bux here and there, but the panels alone are probably
worth $3000 now. (The charge controller, a pulse-width-modulation 3-stage
charger with sense wires and profile selection for battery chemistry, along
with automagic battery voltage selection, was less than $60.)
In summary, you can use batteries and they can be quite useful, but
do some serious thought before you jump in.
> 73, Bill W4ZV
>
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--
Eric F. Richards
efricha@dimensional.com
"The weird part is that I can feel productive even when I'm doomed."
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