Adding External Power Receptacle

[Browncbr1]

is there something wrong with hooking jumper cables up directly to the battery terminals if a jump start is needed?

Is the whole purpose of the plug to eliminate the need to reinstall the battery box top and tail door after starting?

Edited November 21, 2016 by Browncbr1

[Marcopolo]

Hooking jumper cables directly to the batery to run the avionics for long periods of time would be ok, but to jump start the airplane would be troublesome.  Putting the battery box cover on with the enigine running and the airframe vibrating and trying to keep the avionice door from blowing away in the prop-wash seems like too much work.

 

Just sayin!

 

Ron

[carusoam]

Convenience, simplicity, no mistakes...

no magic... 

You can start the plane and taxi away, after somebody with minimal training disconnects it...

Best regards,

-a-

[Cyril Gibb]

I'll be a contrarian here.  I see two potential uses for the external plug; running avionics on the ground and jumping a dead battery.

A battery charger is almost as easy for avionics practice on the ground and is inexpensive.  Secondly, if you jump start a dead or almost dead battery and then fly, doesn't the subsequent extreme charging rate risk overheating the plates and damaging the battery?  Also, I think that rapid charging of a lead acid battery can generate a reasonable amount of hydrogen gas in the tailcone.  Enough to be a concern?

If I killed my battery,  I'd just do a slow charge and go get a bite to eat. 

[Raptor05121]

1 hour ago, Cyril Gibb said:

I'll be a contrarian here.  I see two potential uses for the external plug; running avionics on the ground and jumping a dead battery.

A battery charger is almost as easy for avionics practice on the ground and is inexpensive.  Secondly, if you jump start a dead or almost dead battery and then fly, doesn't the subsequent extreme charging rate risk overheating the plates and damaging the battery?  Also, I think that rapid charging of a lead acid battery can generate a reasonable amount of hydrogen gas in the tailcone.  Enough to be a concern?

If I killed my battery,  I'd just do a slow charge and go get a bite to eat. 

This. Exactly.

If the battery is dead as to not able to start the airplane, its technically un-airworthy if I read my Concorde pamphlet correctly. And these battery doors bypass the battery and go straight to the solenoid, at least the one on my D model does. I have no need to power anything on my instrument panel so its useless to me. I wish it was a charging receptacle.

[mooniac15u]

50 minutes ago, Raptor05121 said:

This. Exactly.

If the battery is dead as to not able to start the airplane, its technically un-airworthy if I read my Concorde pamphlet correctly. And these battery doors bypass the battery and go straight to the solenoid, at least the one on my D model does. I have no need to power anything on my instrument panel so its useless to me. I wish it was a charging receptacle.

There are airworthiness standards for certification and for capacity testing. Can you point to a specific FAR that prohibits flight with a partially discharged battery?

[Raptor05121]

I'll have to find it. IIRC, it has something to do with having so many minutes of battery life left in the event of an alternator failure.

[mooniac15u]

Just now, Raptor05121 said:

I'll have to find it. IIRC, it has something to do with having so many minutes of battery life left in the event of an alternator failure.

Are you talking about 23.1353?  That is a certification standard.

[Bob_Belville]

I've been running avionics and charging the battery this week with a charger connected directly to the battery posts which requires taking the door and the battery box cover off. That's no big deal for those tasks but as has been mentioned above I would not want to do that to jump start the engine with a weak battery. For one thing jumper cable clamps are not that secure and the POS clamp could easily slip and short out to the metal battery box.

With the help of a couple of MSs I think I've found the parts I needs from a salvage plane. I'll have to do some repairing and painting but it will be handy to have.

As Cyril Gibb observed, a running engine (alternator) will charge a battery at a much higher current that a battery charger will. Several months ago my avionics shop thought they were working on my plane using their big external power supply but it must not have been connected so the whole panel was actually powered by my 12V Concorde for 4 hours. Nice warm day and the plane started right up! But the JPI was indicating 50 amps. I watched that for a while and called the shop from my cell phone. We watched the EDM for a while and figured out what must have happened. Amps backed off a little, probably still 40+, so I took off and flew home uneventfully. I would not want to make a habit of that.    

 

 

[Yetti]

14 hours ago, Cyril Gibb said:

  Also, I think that rapid charging of a lead acid battery can generate a reasonable amount of hydrogen gas in the tailcone.  Enough to be a concern?

If I killed my battery,  I'd just do a slow charge and go get a bite to eat. 

The rear battery box is positive vented with tube facing forward and a vent facing back.  There is a seal on the lid.   To get the back cotter pin in on the latch up against the rear firewall is a PITA.  Good luck with the plane running and bouncing around.  It may be time to replace the cotter pin with a tractor pin spring key thingy. But it is only a several times a year thing.  If you killed your battery and wanted to charge it correctly, you would need lunch, dinner and probably breakfast. Had the line guys jump a 172 with the plug on the firewall.  I was scared for them.  It violates my rule of moving in front of the wing with the prop turning.