[Milsurplus] Batteries for PRC-47

[aGEnuine ham]

On Sun, 8 Sep 2002 16:29:26 EDT UHFSATCOM@aol.com writes:
> This may sound kind of dumb, but I'm a machinist...not an 
> electrician. I have 
> a PRC-47 I'd like to run on batteries. If I put four 6volt/7AH gel 
> cells in 
> series...will that give me the 24vdc
YES
/25ah
NO
 I need for the PRC-47? And 
> if so, 
> would I use a 24vdc charger..and at what rate? The reason I ask is 
> that it 
> seems almost impossible to find a battery made for the PRC-47 but 
> you can buy 
> Powersonic 6v/7ah batteries for 14 bucks a piece. 

When you series batteries, the voltage adds, the current capacity stays
the same.  When you parallel them, they discharge each other, but if they
didn't the voltage would be the same, and the ampere hour capacity would
be added.  To do what you want, you need to put 4 ea. 6V 25 AH batteries
in series. Or 2 ea. 12V 25 AH batteries.  For gel-cells, you need a
constant voltage charger, set up for about 2.40 volts per cell, depending
on exact chemistry, to fully charge them, and 2.20 volts per cell after
they are charged to float them.  This battery charging is a complicated
matter to do correctly, which is why so many people experience such short
lives and complain about them a lot.  Most people take the easy way out
and use deep discharge RV batteries, which are messy, generate hydrogen
when charging, and are heavy.  Too bad you weren't in Texas last year. 
There was a fellow selling 12V 30AH gel cells at Ham Com for $15 ea.  $30
and you're set.

Good luck,
73,
W5VPQ


________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today!  For your FREE software, visit:
http://dl.www.juno.com/get/web/.