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Stu:

"Aircraft" batteries are bad news. They are expensive, they are built in short
production runs and they leak a fluid that is about as friendly as the blood in
the creature from "Alien". Automotive batteries are poorly suited for the
vibration and G loads. Lithium Ion and Nickel Metal Hydride are expensive and
require special chargers plus Lithium Ion will catch fire if abused. Marine deep
cycle may be a good choice.

The best jolt for the buck in my book are the GR Lead Acid. Their chemistry is
tuned so that the gas products from electrolysis are recombined (GR, gas
recombinant, get it?). These batteries represent the next generation after Gel
Cells (gelled or immobilized electrolyte), were developed for the UPS (the
uninterruptable computer power supplies, not the guys in the brown shorts) market
and are made in high volume by Matsushita, aka Panasonic. You can get them from
Allied or Digikey but I would recommend B&C Specialty.

These batteries can be mounted in ANY orientation, have lots of cranking amps and
you could cut one in half without that alien blood gushing out.

A 12 volt, 28 amp hour battery is 6.5 x 4.92 x 7.07, weighs 24 lbs, costs about
$75 and will easily hot start a Lycoming 540. I use two 17 amp hot batteries (7.3
x 3.0 x 6.58, 14 lbs) in series in my IV and replace them every two years on time
(not because of performance). A 17 amp hour battery with a B&C geared starter
should wind up a 360 just fine.

Remember to always disconnect the ground wire (usually the negative) on the
battery first and reconnect it last. This way when the other end of your spanner
touches something metal it won't give you a lesson in Ohm's law.

Brent

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