battery charger to get through Piper power port?

(John_F) writes:

What you need is a REGULATED lab power supply that has adjustable
voltage and current adjustments. I use a 0 to 33 volt at 0 to 30
amp power supply that has digital readouts for voltage and current
that I bought surplus.

The last thing a pilot wants in a hangar is a lab-grade supply. They don't
tolerate abuse well...

The regulator-modules I referred to, such as
http://homesecuritystore.com/ezStore123/DTProductZoom.asp?productID=1037
or many other units, produced regulated 13.8v/etc to charge the
battery. I'd not worry too much about current limiting; the wallwart
powering it helps there..and the regulator will as well. (The units
typically produce an amp or two at best; & with most wallwarts, far
less....)


You cannot feed the power into the APU port for a long time (more than
10 minutes) or it will generally fry the APU port relay because most
are not rated for continuous operation.

True! That's another reason I did not suggest such. It's a Bad Idea.

Install a charging jack on an inspection panel and wire it direct to
the battery with a FUSE at the battery that will support the expected
charging current from your power supply.

This is an approach as well. But the OP likely wanted to avoid drilling
more holes in his aircraft....I wonder why?

These voltages need to be adjusted some what if the
temperature is not close to 70F. This voltage verses temperature data
can be found on the internet for the type of battery you are using.

True, but you can just err on the low side; you do NOT want to
overcharge the battery. Note the alternator does not know the battery
temperature, either.


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Kyler:

However...using the existing power port is handy. The best thing about
it is that it's externally accessible.


A downside is the size and $$$ of the mating connectors.

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

: 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...

I haven't really been following this thread too closely, nor have I looked at
the schematics, but it sounds like it's wired from the factory with a safety
interlock that you are proposing to bypass. When I worked on the HEV project at UIUC,
we had a similar setup with the big charging plug... basically in order to charge the
car, there had to be 14v present *in the car* to close the relay to enable the
high-voltage contactor. There were also diodes present in the HV line to make sure it
was impossible to discharge the battery out the charging port. Granted, a lot of
safety issues are reduced when both sides have a max of 15v, rather than the 350 I was
working with, BUT...

The way it was wired from the factory no doubt was pontificated upon a great
deal. I suggest you consider *ALL* possible failure modes and do the appropriate
official paperwork approved. Making big sparks in an aluminum plane is not good for
its structural soundness. Even if "Cooter the Airplane Mechanic" has done it 100
times before, it only takes one error to have a 1" hole burned in the side of the
plane.

-Cory

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************