[Fwd: Re: [Elecraft] What battery to use?]

[Paul Heller]

Robert Tellefsen wrote:

>Paul
>What is an AGM battery?  Don't think I've heard that term before.
>Thanks and 73
>Bob N6WG
>
AGM = Absorbed Glass Mat

As I understand it, the original application was for military aircraft - 
they can be mounted in any position and don't give off hydrogen under 
normal circumstances.  I've used the Optima 'D31M Blue Top' model in 
several long-run UPS applications and they've really worked out well.  
Wal-Mart marine batteries are cheaper (1/3 - 1/2 the cost of AGM) and 
supposedly have more AH capacity, but the AGM batteries seem to have 
significantly more capacity, last for years, and you don't have to worry 
about acid spills or fumes or hydrogen.  Supposedly they won't leak even 
if the case gets cracked, though I haven't tested this scenario and hope 
not to ;-)

There are some vendor writeups with more info at:

http://www.reactual.com/metaefficient/archives/deep_cycle_batteries/index.html
http://www.windsun.com/Batteries/AgmTech.htm
http://www.1st-optima-batteries.com/
http://www.dcbattery.com/agmtech.html

A number of eBay sellers carry these.

/Paul

-- 

 /Paul Heller W3PH
  ph at his.com
  http://www.his.com