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Author Topic: Fun with power  (Read 732 times)
KC2ELS
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« on: November 14, 2003, 06:09:36 PM »

A similar post was made to rec.radio.amateur.misc.

My goal is to design a station that:
 * continually charges its batteries,
 * maintains power uninterruptedly when commercial power fails, and
 * can handle batteries being switched in and out.

My goal is to use two power panels -- one for consumers and one for producers.  The two panels would be connected together by thick wire terminated in Anderson connectors.
The producer panel would have one connection for the power supply, which leaves four connections for batteries.  The batteries are all the same make and model and age, all large deep-cycle batteries.

Is it really this easy?  Am I missing something?  Should I modify the power supply so it doesn't get zorched when commercial power fails?  Should I install some kind of relay between the battery and the panel to prevent the battery from being damaged by low voltage?  Will I have any trouble with the radio equipment if I plug in a fresh battery in parallel to a nearly-spent battery before unplugging the nearly-spent battery?
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K9KJM
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« Reply #1 on: November 16, 2003, 04:34:31 AM »

I run all of my radio equipment (And lights etc) on
battery power full time both at my own hamshack and
at several remote tower sites. Works great.
The "secret" is to have a charge system that
shuts off to zero when your battery is fully
charged.
I have tried using a number of batteries in the
past with poor results. ONE marine deep cycle
battery is PLENTY to run several radios for
close to eight hours with no charger going......
Just connect all of your equipment to a single
(GOOD) battery, and then work out an automatic
charging system (I use Schumacher automatic chargers)
There is a GREAT article in the latest QST magazine
about battery power.
You cannot connect batteries in parallel without
some type of isolation diode or similar........
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KC2ELS
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« Reply #2 on: November 16, 2003, 06:37:24 AM »

I currently use a "battery tender" to keep my batteries charged.  I don't have an uninterruptible setup at the moment -- that's what I'm hoping to design here.

The reason to support two batteries is bifold -- with Field Day rules, a battery-powered station can charge its batteries offline using wall current or generators and still count; and in a real-life emergency situation, I'd probably want to switch without shutting down everything.

I looked at the latest QST and didn't see the battery article.  Could you tell me which article you saw?
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N8FVJ
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« Reply #3 on: November 19, 2003, 10:24:58 AM »

Regarding isolator diodes, use low forward voltage drop Schottky rectifiers. A 'regular' diode will lose about 1 volt when inline as an isolator. Some radios do not perform well on 10.5 to 11 volts.
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KC2ELS
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« Reply #4 on: November 20, 2003, 05:17:27 PM »

Hmm.  Should I wire the diode in the positive power lead, or across the two terminals, or what?  I'm looking online, and all I can see is that Schottky diodes are good for reverse battery protection, nothing about isolation.
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KC2ELS
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« Reply #5 on: November 20, 2003, 06:55:13 PM »

Oooh!  I think I understand what you meant with regard to the diodes.

http://www.ibexmfg.com/appnotes/app07.htm

This page discusses UPS design.  The second diagram looks like it would meet my needs -- keep the battery continuously charged while running the station, with the station using the power supply to run during normal conditions.  The diodes in the diagram are even Schottky rectifiers.  Hmm.

Thanks for your help!
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KC2ELS
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« Reply #6 on: December 02, 2003, 03:39:08 AM »

I recently received the December QST which has a very nice article on battery power.  Thanks!
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KD7EZE
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« Reply #7 on: February 22, 2004, 12:41:43 PM »

KJM---
  Your statement that you cannot connect batteries in parallel without a diode is TOTALLY FALSE. My entire house, including detached hamshack, runs off of battery power. Solar and wind power, to be more exact. Nonetheless, the solar panels and wind generators charge the batteries. There are 100 batteries connected in a series/parallel circuit, with NO diodes. I tap 12V power for the radios, etc. and the rest is fed to Trace pure sine-wave inverters. The initial cost for such a setup is quite large for the average joe, but it will pay for itself in time. Besides, I have all of the power I will ever need, and I'll never get an electric bill.
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