"Denny" writes:

1. Simplest solution is a dumb charger that doesn't know whether it is
attached to a battery or not...

That's where I was headed but, as you described, it wouldn't be good for
long-term use and that's what I really want. I'd like to just plug it
in when I put away the plane, just as I do for the engine heaters. That
way I'd be able to run the cabin heater for awhile when I'm getting
ready for the next flight without worrying so much about the battery not
handling it.

Stepping down the voltage is certainly an option. I'm not looking for a
fast charge.

2. Next solution is to have a small battery attached to the output of
the charger which will supply the load to activate the charger and also
to operate the solenoid in the plane..

I finally stumbled on to that yesterday. I have a portable "jump start"
battery (with a handy inverter attached). I realized that if I connect
that to the power port and then plug its charger into it, I have
basically what I want. It would also be handy for helping to run the
heater after I pull the plane out of the hangar, especially on trips
away from home (where I could charge it at a hotel or in a rental car).

3.. Best solution! Have your mechanic change the Positive lead from
the Piper plug so that it goes around the solenoid and directly to the
battery... This is how I have Fat Albert The Apache wired (and every
airplane I have ever owned) for charging and jump starting...

You had no problem with that?! Cool! I wanted this anyway because I'd
like to make a 12VDC tug and the power port is sitting right there just
begging to be used. (Having my tug not start recently makes this even
more enticing.)

Sidenote: I didn't realize the small airplane tug was invented right
here at Purdue...in 2003 (well after I bought my PowerTow).
http://news.uns.purdue.edu/UNS/html4...fi.towbar.html

Otherwise, pilots have to muscle their planes into place with
a manual towbar or have someone at the airport use a tractor-
like towing vehicle,

There must have been some reason to have the port "protected" by the
relay. Are we sure that this is safe and not (more) likely to rankle
any FSDO types? I sure don't see the harm in it other than producing a
signficant reaction if a conductor is jammed into the port. I wouldn't
mind replacing the solenoid with a manual switch inside the nose
baggage compartment.

Thanks!

--kyler