Re: [IRCA] Lead Acid Cells

["Guy Atkins" <dx@xxxxxxxxxxxxx>]

Hi Charles,

I think you would want a deep cycle ("RV" or so-called marine) battery.
These are designed to endure the occasional full discharge, which for
regular lead-acid batteries (as in a car) drastically shortens their
lifespan.

I've used deep cycle batteries for years for 12vdc DXpeditions away from
powerlines and various AC-related noise sources. Walmart sells one that is
the best value I've found; it costs approx. $56 in my area. It is called
"Everstart Marine", and has a rating of 116 amp-hours and 160 reserve amps.
This battery will power your frequency standard for a *long* time before
needing recharging! According to the calculator on this Web site, this
battery would provide 460 hours of operation @250 mA current draw:
http://www.spectrumbatteries.com/calculator/batcalc.htm


It's not wise to run down even deep cycle batteries on purpose periodically
(to my knowledge), but they aren't harmed by it the way standard lead-acid
batteries are.

Guy Atkins
Puyallup, WA 
www.sdr-1000.blogspot.com




Date: Fri, 15 Sep 2006 21:58:23 -0400
From: Charles & Leonor Taylor <calltaylor@xxxxxxx>
Subject: [IRCA] lead acid cells
To: irca@xxxxxxxxxxxxxxxx
Message-ID: <6.0.3.0.2.20060915214526.02a984f0@xxxxxxxxxxxx>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Crew,
I have a 12-V secondary frequency standard that draws 250 mA. It has a 
proportional temperature heater on the crystal and was a surplus out of 
some quality synthesizer. Excellent stability.
I want to power it from an auto battery, as NiCads or such are just too 
expensive for me now. So I know someone out there can give me good advice 
as to what type gives good value/price.
Another thing, would it be wise to let the battery run way down
periodically?
I suppose GPS is simpler, but that's not fun. I like to be able to say I 
can maintain dead-on accuracy simply by knowing the aging rate of the
crystal.
73,
WD4INP
Charles & Leonor Taylor
Grifton, N.C. 

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