AC to DC Converter for APU

[Newps]

Jim Burns wrote:
> This is for all the RV'ers and/or pilot/campers in the group. I'm wondering
> if anybody has ever made an "APU" out of an RV type AC to DC power
> converter.

I do some airplane camping each year as well as own a fifth wheel.


>
> I was wondering if something like the RV converters that take 120AC and
> convert it to 12DC could be used to hook up to the apu plug of our Aztec. I
> can think of several uses that take more amps than what a little battery
> charger would put out, plus it would be super portable.

Where does the DC come from? You're not starting with your airplane
battery are you?


>
> I see that there are several different output amperages available. 30 amps
> would probably do everything I'd want.

A rule of thumb for these setups is you need 10 amps of battery power
for each 100 watts of AC power generated.


Our cabin heater, fans, and fuel
> pump draw a max of 20 amps. If it is even possible (and safe) could it be
> used for jump starting the engines?

Are you asking if you could use the aircraft battery to jump start the
airplane? That makes no sense. If the battery can't start the plane
the normal way then hooking up an inverter, which has some loss to
inefficiency, will never start the plane. If you want some electricity
the easiest way is to find yourself a Honda 1000 watt generator. They
weigh hardly anything, are very quiet and run about 20 hours on a gallon
of gas. They can be found used on ebay for between $400-500.


Each starter draws about 15 amps max.

Yeah, but in reality once one is started you got free juice right?

[Newps]

Jim Burns wrote:
> Oops... what I'm talking about is backwards from what you are talking about.
> I'm talking "converter" not inverter. I want 12volts DC from a 120AC
> outlet.
> Plug a power cord into a 120 volt AC. Plug the female end into the DC
> converter. Wire the converter output leads to a Piper APU plug. Plug it
> into the nose socket to supply 12 volts to the system.

That's easy. Get a bigger charger than what you originally were talking
about. Like this one from Sears.

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=AUTO&pid=02871222000&adCell=P9

[Jim Burns]

This is for all the RV'ers and/or pilot/campers in the group. I'm wondering
if anybody has ever made an "APU" out of an RV type AC to DC power
converter.

I was wondering if something like the RV converters that take 120AC and
convert it to 12DC could be used to hook up to the apu plug of our Aztec. I
can think of several uses that take more amps than what a little battery
charger would put out, plus it would be super portable.

I see that there are several different output amperages available. 30 amps
would probably do everything I'd want. Our cabin heater, fans, and fuel
pump draw a max of 20 amps. If it is even possible (and safe) could it be
used for jump starting the engines? Each starter draws about 15 amps max.

Has this been done? tried? or is it nuts?

Jim


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[Jim Burns]

Oops... what I'm talking about is backwards from what you are talking about.
I'm talking "converter" not inverter. I want 12volts DC from a 120AC
outlet.
Plug a power cord into a 120 volt AC. Plug the female end into the DC
converter. Wire the converter output leads to a Piper APU plug. Plug it
into the nose socket to supply 12 volts to the system.

Clear as mud huh? :)

Jim



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[David Lesher]

"Jim Burns" > writes:

>This is for all the RV'ers and/or pilot/campers in the group. I'm wondering
>if anybody has ever made an "APU" out of an RV type AC to DC power
>converter.

>I was wondering if something like the RV converters that take 120AC and
>convert it to 12DC could be used to hook up to the apu plug of our Aztec. I
>can think of several uses that take more amps than what a little battery
>charger would put out, plus it would be super portable.

You can use a bigger battery charger, provided it's "smart" as most
all are now-a-daze. That's all that's in a "RV" unit...unless such
also has a DC->AC invertor, and you don't need that.


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A host is a host from coast to
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Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[Dave Butler]

Jim Burns wrote:
> Each starter draws about 15 amps max.

Just based on my intuition, that seems low. You sure? If only 15 amps why do
they put such whoppin' big cables on 'em?

--
Dave Butler

[Newps]

Dave Butler wrote:
> Jim Burns wrote:
>
>> Each starter draws about 15 amps max.
>
>
> Just based on my intuition, that seems low. You sure? If only 15 amps
> why do they put such whoppin' big cables on 'em?

I would think starters would hit 50 amps with some regularity and spike
up to 100 amps.

[David Lesher]

Newps > writes:



>>> Each starter draws about 15 amps max.
>>
>>
>> Just based on my intuition, that seems low. You sure? If only 15 amps
>> why do they put such whoppin' big cables on 'em?

>I would think starters would hit 50 amps with some regularity and spike
>up to 100 amps.

Are we talking starters as in Kettering & engines? Try 100's of amps.

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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

[Don Hammer]

>>>> Each starter draws about 15 amps max.

Maybe a 15 amp breaker for the starter control circuit. A starter is
series wound and will draw the current it needs straight from the
battery. I would think that several hundred amps peak would be
normal. The starter/generators on small turbine engines draw as much
1200 amps when you hit the button then taper off as the load
decreases. I've seen GPU power cables jump 6" off the ground from
the initial surge!

If you want to use a power supply to keep the battery from running
down while the aircraft is powered up in the hangar, most any source
of DC capable of putting out the amps drawn will work. What I don't
know is how well one of those converters filters out ripple. Since
one end is plugged into alternating current, unless there are some big
capacitors in there, you will get pulsed DC out the other end. I
don't think that would be good for the avionics, but I imagine that
the battery in the circuit would smooth things out.