[450] battery backup project

[n1ujs at toast.net]

Thanks for your input George.  Always good to hear
from a man of science.  I tend to be more reckless in
my "mad scientist" endeavors of course, but will take
your warnings under advisement!



------- Original Message -------
>From    : George Andrews[mailto:gandrews at ntplx.net]
Sent    : 12/13/2009 12:25:30 PM
To      : 450 at lists.vhfwiki.com
Cc      : 
Subject : RE: Re: [450] battery backup project

 
Bob,
 
I would only trickle charge the batteries as a 
routine (100 mA or less) once they are brought to
full charge. Much better is to 
charge such batteries as needed. These do not appear
to be SLA's, so there will 
be venting. What gets vented is Hydrogen gas
(flammable, can have an explosive 
concentration issue and over time, years, will belch
a very tiny amount of 
dilute sulfuric acid). Hydrogen flame is invisible
unless it is burning 
something else. I would keep such a setup out in a
well ventillated 
garage and consider the fact that car batteries can
explode. Hydrogen 
builds up, there is an arc inside the battery or a
source of ignition external 
to the battery. This will splatter the sulfuric acid
over an area and on people 
if you happen to be nearby. Then there is the
shrapnel from the battery 
case!
 
I had a battery blow up in a 64 Chevy. It was a 
Sears battery with a year or so to go on the
warranty. I thought I was the 
victim of a car bomb (radical politics days-thought
the Birchers got me) and my 
ears were ringing for hours afterwards. The only
idenfifiable part of the 
battery case was th botton inch or so and some of the
lead plates. It was 
terrible decontaminating everything under the hood!
 
The inverter will be expensive and might generate 
noise on HF.
 
All my stuff is 12 V, including a CFL that lights 
up the shack.
 
The 130 A/hr telcom batteries at the hamfest are a 
better idea.
 
You could build a Schottky diode device to trickle 
charge and automatically switch over to battery on
power failure.
 
George

  ----- Original Message ----- 
  From: 
  Bob 
  To: 144.450 Mailing List 
  Sent: Sunday, December 13, 2009 11:44 
  AM
  Subject: [450] battery backup 
  project
  

  Successfully revived two Orbital batteries for 
  backup purposes. 
   
  
  Battery specs. are here:
 
http://www.remybattery.com/Products/Exide-Orbital-ORB78DT-84-Starting-Battery__ORB78DT-84.aspx
   
  The plan is to tie them together as a backup 
  supply for the entire shack in conjunction with an
inverter (anyone got one 
  cheap to trade or sell?).  
  Total cash outlay so far, $18.00 ("core 
  value" for the two batteries).  They were new, but
on the shelf at 
  work since '05.  
  They seem to be good as new after charging with 
  my Samlex APS 1215 (shown below, 15A cont., 20A
surge) which will be devoted 
  to keeping them charged.
   
   
   
   
   
  
  

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