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Battery Power Receptacle

Posted: Wed Feb 04, 2009 5:51 am
by 170C
Although I don't think it was an option on C-170's or early 172's, later model single engine Cessna's had an option for the above referenced item which permitted a special jumper cable to be inserted into the receptacle to "jump start" the engine if the battery was too weak to start the engine. I am wondering how complex it is to install one on our early birds. Since the bottom cowling is removable and usually is removed for oil changes, etc., that lower cowling is not the location, IMO, to mount the receptacle. Would attaching it to the lower firewall be the best location? My plane has simply gotten to where I cannot prop it if the battery fails (maybe it is me, not the plane :? ) and trying to put auto jumper cable clamps on the battery posts just doesn't work, especially the + post so if I have to jump start it I have to have someone hold the clamp onto the battery relay. This is unacceptable, especially if there is noone else around to assist. Give me some guidance please. I thought these used to be listed in Spruce, but haven't located them and I suspect most salvage yards would probably have them for sale.

Re: Battery Power Receptacle

Posted: Wed Feb 04, 2009 11:23 am
by 53B
Hi Ole Pokey,

The external power plug was indeed an option for our airplanes (not sure about the 170's). See figure 88 of the Cessna parts catalog P257-12 for our airplanes. If you don't have one, I can try to post the pages later or at least email them to you.

Re: Battery Power Receptacle

Posted: Wed Feb 04, 2009 2:13 pm
by GAHorn
Here's pg 152 of the 170B IPC:
ANPlug2.JPG
Here's pics of my "ORIGINAL (mosty)" installation, complete with oil leak:
MVC-073S.JPG
And from below:
MVC-072S.JPG
I think I may have a couple spares sitting around here, if Ol' Gar hasn't stolen them.

Re: Battery Power Receptacle

Posted: Wed Feb 04, 2009 2:20 pm
by 4583C
Frank
Spruce still has the receptacle. If you're like me the problem in searching for something is proper nomenclature. In this case I searched for "jumper cable" When the description of the cables came up and told me they mated with AN2551 plug, I then put " AN2551" in the search box and found the receptacle.

Re: Battery Power Receptacle

Posted: Wed Feb 04, 2009 2:28 pm
by GAHorn
The IPC calls for a AN-2552-2 plug, which has only two major prongs. The -3 plugs can also be used, just don't attach the 3rd plug to anything, (It normally provides an activation circuit which the 170 installation does not utilize.)

Paul, the AN 2551 plug is the FEMALE plug that is usually attached to the jumper-cable assembly, and plugs into the AN 2552 receptacle.
\
Aircraft Spruce sells the AN-2552-3a plug for about $68. You will also need a mount bracket, and the cables, grounding strap, and two end-fittings, etc. to complete the installation, which is a minor alteration "in accordance with" Cessna dwgs.

Re: Battery Power Receptacle

Posted: Wed Feb 04, 2009 3:35 pm
by W.J.Langholz
53B wrote:Hi Ole Pokey,

The external power plug was indeed an option for our airplanes (not sure about the 170's). See figure 88 of the Cessna parts catalog P257-12 for our airplanes. If you don't have one, I can try to post the pages later or at least email them to you.
Hey Ole Pokey....53B has a plane just like yours..............there might be hope for me someday after all :D If we get our poop in a group we could start a discussion page titled "The 170 and Change Group"..........

Re: Battery Power Receptacle

Posted: Thu Feb 05, 2009 4:12 am
by blueldr
What seems to be the objection to installing this external power connection using the third pin on the male connecter? This pin provides a ground connection to a master type solenoid, the installation of which precludes an open spark when conncting or disconnecting the external power cord if there happens to be any electrical load on the line.

Re: Battery Power Receptacle

Posted: Thu Feb 05, 2009 5:06 am
by 170C
Guess I need to do some checking on possible sources of the receptacle and female plug/cables at salvage outlets. I was told that on at least some installations that there is some type of devise that protects any avionics that may have been turned on, apparently to preclude any electrical spike when using the jumper. Apparently it disrupts the circuit to the bus bar or avionics switch, if so equipped. Looks like the firewall is the logical location for the installation. Any additional insight appreciated as well and thanks for the info.

Re: Battery Power Receptacle

Posted: Thu Feb 05, 2009 6:21 am
by db99577
I just picked up my female plug (sans cables) from Stoddards on Monday. The receptacle was installed when I bought the plane.
I will look into Mr. Elder's observation. It makes too much sense not to look into. Thanks

Re: Battery Power Receptacle

Posted: Thu Feb 05, 2009 6:24 am
by DaveF
Here's how Cessna did it in the '70s. The GPU plug's third pin is connected to (+). It's shorter, so it makes contact last. When the plug is inserted, first the battery contactor is energized and power is sent to the other contactor. When the third plug pin touches, the other contactor closes, and GPU power goes to the battery. Where the schematic says "to starter contactor" also goes to the battery. As BL said, this sequencing prevents a spark from occurring at the plug/receptacle. Power on the third pin also disables the avionics bus relay, as does power from the starter switch. Note the two diodes in series. The original designs had only one, and if that one failed by shorting, the starter would energize when the GPU was plugged in. That's a bad thing so Cessna added a second one. By the way, the avionics bus relays are not very reliable and as they fail they are often jumpered out or replaced with an avionics master switch, making it possible to power the radios on the ground with the GPU.
210GndPwrDescr.jpg
210GndPwrSch.jpg

Re: Battery Power Receptacle

Posted: Fri Feb 06, 2009 4:47 am
by n2582d
gahorn wrote: Here's pics of my "ORIGINAL (mosty)" installation
Hey, "Mr. Originality" are those threaded nutplates in place of the NAS 444 tinnerman anchor nuts I see on that firewall? 8O Better post those pictures with a little less resolution! You might lose your title! Actually, that looks like a nice modification to me as does the battery power receptacle.

Re: Battery Power Receptacle

Posted: Sat Feb 07, 2009 2:50 am
by HA
I'd have kept the tinnermans George, less fiddling around while trying to reach under the pedals to get those screw started :wink:

If I flew my airplane in the cold more often I'd install a GPU plug, and I like George's placement to keep things at least "looking" original. and everytime BL contributes something my respect for his depth of knowledge grows - hey Dick, you want to run over to McClellan and give the mechanic that works on our C340's some pointers for me?

Re: Battery Power Receptacle

Posted: Sat Feb 07, 2009 4:49 pm
by GAHorn
blueldr wrote:What seems to be the objection to installing this external power connection using the third pin on the male connecter? This pin provides a ground connection to a master type solenoid, the installation of which precludes an open spark when conncting or disconnecting the external power cord if there happens to be any electrical load on the line.
Any external power should be OFF while making the connection. Power should be applied only AFTER the connection is completed, when using the originally specified AN2552 receptacle, which is directly connected to the battery as specified in the IPC.

I would like to remind all my friends that my motto is not "originality". It is "an originality nut (mostly)...

Also, I am not "Mr. Originality" (despite Richard Pulley's faux pas.) "Mr. Original Nut-plate", perhaps. :lol:

More seriously, ... I did not install those MS21047 nutplates. That firewall arrived from Cessna with those nutplates already installed. Go figure.

Re: Battery Power Receptacle

Posted: Sat Feb 07, 2009 6:35 pm
by blueldr
George,
In the event you're using an external power cord connected to a battery, how do you turn the power OFF to make the connection?

Re: Battery Power Receptacle

Posted: Sat Feb 07, 2009 6:42 pm
by GAHorn
Do you mean to say that your female AN 2551 plug is connected to the battery-cart directly, with no method of disconnection from the cart batteries? IF so, I'd say that is an unsafe arrangement. The AN-2551 should always have a method if disconnection of electrical service from the source.

The 100 Series Service Manual instructs that the aircraft battery Master should be ON, prior to connecting the external power source. (This is to provide the aircraft system a "shock absorber" using the ship's battery.)

The external power source is only activated after the connection is complete. When disconnecting the external power, the external power source should be powered off first, then the source powered down (if it's generator-powered.) The AN-2551 is disconnected from the aircraft last.