electrolyte as there is with a conventional
flooded-cell battery.
Finally, the AGM batteries are more
expensive. As I’m writing this, a flooded-cell
Gill G-243 battery with acid lists for $644.44
and can be purchased at Aircraft Spruce for
$343.95. The comparable Concorde RG-24-
15 AGM battery lists for $935.95 and sells at
Spruce for $439.
Please note the huge markup on aircraft
batteries! If you have your shop replace your
battery, be warned that they’re likely to
charge you list price (this is standard industry practice). If you replace the battery
yourself (which you are permitted to do
under the FARs as preventive maintenance),
you may save many hundreds of dollars.
WHAT TO BUY
Two companies make starting batteries for
piston GA aircraft: Teledyne Battery
Products (who sell them under the “Gill”
trade name) and Concorde Battery
Corporation. As I’m writing this, both sell
both kinds of batteries: flooded-cell and
sealed AGM.
Many owners prefer the “
maintenance-free” sealed Concorde AGM batteries,
particularly for aircraft based in hot climates
where the lower self-discharge rate of the
AGM battery offers a decisive advantage.
The AGM batteries are great if you are careful not to let them discharge too far. Use of a
GPU during maintenance is a must with
these batteries, and use of a trickle charger
during periods of disuse is highly
recommended.
In Part 2 of this article in the next issue
of EAA Sport Aviation, we’ll discuss the care
and feeding of aircraft batteries, including
charging, conditioning, capacity testing, and
how to decide when it’s time to replace.
Mike Busch, EAA 740170, was the 2008 National Aviation
Maintenance Technician of the Year and has been a pilot for
44 years, logging more than 7,000 hours. He’s a CFI and an
A&P/IA. E-mail him at
mike.busch@savvyaviator.com. Mike
also hosts free monthly online presentations as part of EAA’s
webinar series on the first Wednesday of each month. For a
schedule visit
www.EAA.org/webinars.
