On 1/17/2011 12:09 PM, Morgans wrote:

"Ed" wrote in message
...
Thank you, Eric, this is a good start knowing that I have to upgrade a
bit.

How about a different route. How about adding a small 20 amp alternator
to the engine to charge the battery? You charge it on the way down with
a short engine run, or on the ground, assuming you left enough in the
battery to start the engine.

I don't know the Grob 103 details, but most self-launchers do have an
alternator. If not, finding a way to mount an alternator in what is
usually a very cramped location, and making it sturdy enough to keep the
two-stroke engine from vibrating it to pieces, and integrating it into
the electrical system would be a major project.

The recharge current is limited by the battery size, and the 28 Ah
battery means a limit around 5 or 6 amps. Since the current drops off as
the battery charges, replacing 6 Ah means an engine run of at least 1.5
hours. Nobody wants to put an hour and a half on their engine to top off
a battery - the noise alone is enough to seek other solutions!

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)