Solar charging question

"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.

It has the added advantage of being able to recharge in flight, if the need
arises.
--
Jim in NC

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)

"Eric Greenwell" wrote

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!

I see your points, but still am not sure that some increased charging system
could not provide a good answer.

Most engines like that have a flywheel magnet and stator system, and are
pretty anemic in the amount of current they put out. One of the small
alternators from something like a small tractor could be mounted, and a
larger battery installed, probably a wet cell, or other type that could
handle more charging current. If not able to fill the larger battery in a
20 minute run to altitude, it would be darn close, and the larger capacity
would have more than enough to run your electronics all day, even at only
1/2 or 2/3rds capacity. I agree about not running an engine a long time,
just to charge, but if you ran the battery down one day on a marathon
flight, a little run would keep your electrons zinging around the
microcircuits!
--
Jim in NC

On Jan 18, 3:17*pm, "Morgans" wrote:
Most engines like that have a flywheel magnet and stator system, and are
pretty anemic in the amount of current they put out. *One of the small
alternators from something like a small tractor

After suffering for years with motorcycles that could barely light a
decent headlight, it was fantastic to get my current bike, a 1995 BMW
R1100.

It has an 800W alternator. That's a lot of amps at 12V!

I don't know how many of those amps it can put into the battery. It
has power outlets for both rider and passenger intended to plug
electrically heated clothing in to for winter riding. (not necessary
in NZ, so I've never investigated properly)

On Jan 17, 6:17*pm, "Morgans" wrote:
"Eric Greenwell" wrote



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!

I see your points, but still am not sure that some increased charging system
could not provide a good answer.

Most engines like that have a flywheel magnet and stator system, and are
pretty anemic in the amount of current they put out. *One of the small
alternators from something like a small tractor could be mounted, and a
larger battery installed, probably a wet cell, or other type that could
handle more charging current. *If not able to fill the larger battery in a
20 minute run to altitude, it would be darn close, and the larger capacity
would have more than enough to run your electronics all day, even at only
1/2 or 2/3rds capacity. *I agree about not running an engine a long time,
just to charge, but if you ran the battery down one day on a marathon
flight, a little run would keep your electrons zinging around the
microcircuits!
--
Jim in NC

Last time I checked we were talking about an aircraft and associated
weight and balance, saftey and regulatory concerns. Adding a larger
generator and a flooded battery is not something more practical people
would even consider to solve a problem that can practically be solved
with a larger solar panel or a DC-DC charger.

Darryl