External battery connection - C182

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CT583

Pre-takeoff checklist
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CT583
I recently left my plane off the trickle charger and the battery drained during start. So I called up the FBO and they tried to jump start using the Tug. Actually two Tugs since they thought the first one didn’t work.
Apparently, I’m not getting power through my external 3 prong plug on the cowl.
The first indication was it not starting while plugged in. Second, I wasn’t showing any increased voltage on the volt meter or my JPI.

Has anyone had issues with this particular connection being compromised?
I would have thought it was a straight wire to the battery or at least starter to get the plane going.
 
There is a relay for that connection that is probably bad. You should hear a click when the aircraft is connected to power. Also, check the POH for the proper start procedure when connecting.
 
CT583 said:
I would have thought it was a straight wire to the battery or at least starter to get the plane going.
Click to expand...
It's not a straight connection. Each aircraft can be a bit different so what year, specific model, and last 5 digits of S/N and we'll check a diagram. In most cases the wire on the small pin breaks which actuates a relay or if there is a dedicated external power relay that relay may be hung up from lack of use.
 
There is often a small diode and a resistor (and often a fuse) in that circuit to control the contactor. They are subject to burnout. I found one diode in a shorted condition so that it slowly drained the battery.

Like Bell206 says, the make, model and S/N matter.
 
Prongs clean? I’ve put it on and off a few times until the connection improved. Of course always at night in winter away from home lol
 
CT583 said:
I recently left my plane off the trickle charger and the battery drained during start. So I called up the FBO and they tried to jump start using the Tug. Actually two Tugs since they thought the first one didn’t work.
Apparently, I’m not getting power through my external 3 prong plug on the cowl.
The first indication was it not starting while plugged in. Second, I wasn’t showing any increased voltage on the volt meter or my JPI.

Has anyone had issues with this particular connection being compromised?
I would have thought it was a straight wire to the battery or at least starter to get the plane going.
Click to expand...

Have to make sure the ground power supply have the small pin hot to activate the relay. Not all ground power supplies have the small pin hot but most that have seen can be switched on or off for different setups.

Then the small wire on the small pin on your 182 may be broken since it is a small brittle old wire that maybe broken a long time ago and you would never notice until you want to connect ground power.

Which BTW is not made to "jump" your plane. It is there to power your panel but will charge some depending on the output amps if you leave it plugged in long enough.
 
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Here’s a pic of a Cessna external power diode/resister block. It was a fine line crack across the board and wire when I found it. I tried to remove it for repair and it broke into the pieces shown. Like the others have said, there’s a lot of different configurations. Be sure to check your s/n effectivity
 

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I will have to check out the diode/resistor..

I really appreciate the help and will let you know what I’ve found.
 
FWIW, the 182Q POH is different, stating that external power can energize avionics, if so desired.
 
Jim Carpenter said:
the 182Q POH is different, stating that external power can energize avionics, if so desired.
Click to expand...
I might be mistaken but I thought only the restart 172s/182s could use external plug to power the avionics equipment via a dedicated, switched avionics buss. Do you have a reference?
 
Bell206 said:
I might be mistaken but I thought only the restart 172s/182s could use external plug to power the avionics equipment via a dedicated, switched avionics buss. Do you have a reference?
Click to expand...
POH for my R says the same
 
Bell206 said:
I might be mistaken but I thought only the restart 172s/182s could use external plug to power the avionics equipment via a dedicated, switched avionics buss. Do you have a reference?
Click to expand...
I learned to fly in a S model 172s and spent some time at the flight school with the ground power cart to learn the panel. Mainly after they got the G1000.
It was a small unit not made to jump the motor.

When was the first year for a avionics switch for a 172?

My 1980 N 172 has a avionics switch, 28 volts and seems to operate just like the school planes? One of the first things I invested in was a GPU for my 172 to ground fly the plane, especially handy after I got a new panel. It puts out about 20 amps when the battery is low. Then within a few minutes the amp draw goes down as the battery takes a charge. It is not made to jump the plane I don't believe?
IMG_0307.JPG

It has been very handy. When everything is on the plane draws about 5 amps not counting the rear beacon.
IMG_0301.JPG

I use it regularly after my plane sits outside at night on the ramp with the under wing lights on so hopefully no one drives into it since we don't have much lighting by our hangars. I have some pull breakers that I can shut off and have only the LED under wing lights on. Sometimes I leave it out there for an hour or two if I want to use the hangar and then when I push it in I plug it in to ground power and the battery charges back up.
4475.jpg

Or use the plane as mood lighting.
079_2.jpg
 
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Gary Ward said:
One of the first things I invested in was a GPU for my 172 to ground fly the plane, especially handy after I got a new panel. It puts out about 20 amps when the battery is low. Then within a few minutes the amp draw goes down as the battery takes a charge. It is not made to jump the plane I don't believe?
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A ten-amp charger won't start the airplane, for sure. That starter can draw 250 amps.

We had a different unit for powering the airplane for electrical maintenance. It wasn't a charger. It had a 28-volt output that was heavily filtered to mimic battery current. Most older chargers will have a ripply output due to the full-wave rectification of the 110VAC, though the ship's battery will absorb a lot of the noise. Newer electronic smart chargers don't use transformers. They take that AC and break it up and reassemble it into the voltage and waveform they want, and they might be smoother. I have one but have never put the oscilloscope on it. I'd need a high-wattage, low-ohm resistor to mimic the battery's low resistance to do that, since just putting the 'scope across the battery will find a smoother wave due to the battery's damping. And the smart charger won't put out much if it can't sense a battery.
 
ktup-flyer said:
Yes, 78 Q and later do
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Must be the 28v system that triggers the avionics master. The only 28v 100 series I messed with were all restarts. I had installed a few "avionics switches" on the 12v systems to "reverse" the split buss EPU relay. Didn't realize that last production model had upped to 28.
 
The 172M (12V) had a split bus, with the avionics bus controlled by an NC relay that was opened if external power was used, or during start. There was no "Avionics Bus" switch, at least originally. After 50 years, for many of these airplanes, there will be a lot of departure from this diagram.

upload_2022-2-16_17-49-56.png
 
Dan Thomas said:
Newer electronic smart chargers don't use transformers.
Click to expand...

Actually, they do. A transformer is the most practical way to isolate the charger output terminals from the AC power line, which is required for safety reasons. The difference is that a high frequency (>20kHz) transformer is used. This transformer uses a ferrite core and is much smaller, lighter, and cheaper than a laminated iron core 60Hz transformer of the same power rating. Good filtering is much easier at the high frequency and this facilitates implementation of the "smart" features.
 
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