[450] battery backup project

[George Andrews]

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.

   





------------------------------------------------------------------------------


  _______________________________________________
  450 mailing list
  450 at lists.vhfwiki.com
  http://lists.vhfwiki.com/cgi-bin/mailman/listinfo/450
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.vhfwiki.com/pipermail/450/attachments/20091213/3a221033/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: samlexaps1215.jpg
Type: image/jpeg
Size: 8395 bytes
Desc: not available
URL: <http://lists.vhfwiki.com/pipermail/450/attachments/20091213/3a221033/attachment-0001.jpg>
-------------- next part --------------
_______________________________________________
450 mailing list
450 at lists.vhfwiki.com
http://lists.vhfwiki.com/cgi-bin/mailman/listinfo/450