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[aprssig] backup pwr systems

Ray McKnight shortsheep at worldnet.att.net
Mon Dec 4 06:55:18 UTC 2006


I just managed to find this.
It is the "BB" (battery backup) modification for Astron
Power supplies.  Ben, do you chaps have Astron's in VK-Land?
If not, this mod might still be useful if your PSU is of similar
Design.  I am sending this to you separately as I don't think
The SIG allows attachments.  In effect, this mod adds a current
Limiting resistor in line with the voltage regulator IC's feedback
Lines.  It protects the IC from damage.  Other schemes add a Schotky
Diode between the battery and power supply to prevent voltage reversing
To the supply when the power is off.  In this scheme you must increase
The supply voltage to compensate for the forward loss of approx 0.3vDC
Across the diode.  In any event, the supply voltage presented to the
Battery must be high enough to achieve a 100% charge, as the last 10%
Is the hardest and longest to do.  It's around 14.2 volts but I should
Verify that, I also recall a 14.35 or 14.38 depending on battery type,
And that might be charging voltage, not idle voltage after the battery
Has settled down.  Of course, the best way to determine charge is by
Specific gravity.

I'm a firm believer in backup generators.
Generating more than a few hundred watts for extended periods
Is just too much work with solar, wind or battery banks/inverters.
A combination can do it pretty well, but the cost becomes prohibitive
Compared to a generator which can deliver 5000 watts (2500 average at
50% load) using only 1/2 gallon of petrol per hour.  Here in the Seattle
area when I lose power it's usually a minimum of 6 hrs, often 24, and
has been as long as almost 3 days.  I also insist on doing it correctly,
not running extension cords and power strips all over the place, use
a GenTran panel and wire it in according to code, and then you can easily
manage the load, balance the gennie, get 240vAC for stuff like water 
heaters or a 2KW HF amp, and turn circuits on/off as needed easily 
and safely.  Plus you cannot possibly fry the poor power line workers
dangling in a bucket 35 ft above your head in freezing or rainy wx,
trying to get your power restored!

Simple is better, candles work well, as do Coleman camping lanterns,
But in the long run, more than a few hours, I find the generator the 
Cheapest and simplest solution, and safer than inverters and such,
No massive battery banks to deal with and replace periodically, and
It keeps my freezer and fridgerator cold/frozen and I can still watch
Movies in Dolby 5.1 surround sound and take a nice hot shower.

A single deep cycle battery is fine for a few days for a VHF transceiver,
But beyond that I need the convenience a gennie provides.  Everyone should
Evaluate their required needs during emergency power, NOT just what they
Consider comfortable or things they don't want to give up.  In my
Experience more than a few hundred watts of EITHER 12vDC or 120vAC
Are most easily provided by a generator.  VERY IMPORTANT for USA Hams,
It's IMPERATIVE you stabilize your gasoline when you store it or when
It's in the gennie for more than 30 days, otherwise the gas turns to
Jello and ruins the generator very quickly.  I just got mine back from
A major overhaul because old gas gummed the engine after only a few
Hours and it bent a push rod and threw the valve train all out of whack.
Plus the inside of the engine looked like I was burning molasses for fuel.
For the price of gas nowadays you'd think they'd stabilize it for us, but
NO, the 40-odd additives we now must suffer only serve to hasten the demise
Of our engines, not prolong them.

-----Original Message-----
From: aprssig-bounces at lists.tapr.org [mailto:aprssig-bounces at lists.tapr.org]
On Behalf Of Ben Lindner
Sent: Sunday, December 03, 2006 14:46
To: TAPR APRS Mailing List
Subject: [aprssig] backup pwr systems

Hi all,

What sort of backup power systems do people use these days.  ?

eg.

Running a rig from a standard PSU while charging a battery at the same 
time and when the mains power drops out the battery will take over and 
run the radio. Then when the mains power is returned every thing is back 
to normal, battery is charged again from PSU and radio runs from PSU.

Any body have any ideas on how to work this or has a circuit that I can 
build

Ben Lindner
VK5JFK

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