RG Battery Charger by Jim Weir in Kitplanes

Hi,

As an 8-year (or longer) Kitplanes subscriber, and longtime electronics tech
(Army Aviation-trained), I read with interest the articles Jim Weir wrote
about building your own RG battery charger (Kitplanes: March, April, & May
2004). This looks just like the ticket for my application, but I did have
two questions:

First, would sealed reghargable lead-acid batteries (such as the Yuasa
NPH5-12 12V 5Ah) be an applicable model to recharge with this charger (is a
gel-cell a gel-cell a gel-cell, etc.), and what would be the best way to
reduce the charging current to the c/100 that is recommended? Secondly, is
there an easy way to provide a parts list (with quantity, type, current
capacity, and tolerance) for the components in these circuits? These would
be a HUGE help!

As I still rent from my local FBO, and they have apparently had a few acft
returned in the past with dead batteries, they have summarily disabled all
of the cig lighter sockets in all of their acft. I fly with a PDA-based GPS
which requires a 12V source for power, but only drains 250mA during
operation, so I keep a small gel-cell battery in my flight bag with a cig
lighter socket pigtailed to the terminals. It works great, but I'm afraid to
attach that little battery to my auto batt charger, and don't think a 13.8V
wall-wart charger has enough current to push into the battery. The RG
Charger in Jim's article looks like the ticket, but I wanted to be sure that
I was using the right tool for the job, and needed a shopping list to take
to Radio Shack.

Thanks.

Kevin M. O'Brien

Seffner, Florida.