to install Piper style ground power receptacle or not?

[scard]

I am interested in comments about the usefulness of going to the effort of installing a Piper style ground (aux) power receptacle. I have one on hand and think it would be nice for ground ops and for when the wife forgets and leaves the master on away from home when I'm not around . The problems that I see are:
- That thing is a big honkin' piece of equipment.
- would require a pretty big wire through the firewall to the battery.
- I've been flying 13 years and have never had to use ground power away from home (to my amazement now that I think about it).

Potential mounting location would be in the floor on the passenger side right behind the firewall. Comments?

Thanks,
Scott

[Ironflight]

I installed just such a ground power receptacle on my -8 for the following reasons. They might or might not apply to your own situation, and I think that prior experience one way or another will affect each person's decision...

1) I liked the idea of being able to easily feed the airplane external power during the build process. You can also accomplish this by just connect external power in the shop to the battery cables...

2) My previous airplane was a big-engined AA1B. It had a high-compression O-320 on the nose, and the little bitty battery in the back - it was marginal for starting on the best of days. With no external plug, I had to drag jumper cables through the cockpit, over the baggage area, and through the access door ever time I needed to jump start - which was more frequent that I care to admit! I swore my next airplane would have an external jack....I actually found myself canceling trips in the winter because I knew that I would have a tough time getting started away from home - not a good way to utilize an airplane.

3) With my aft-mounted battery, I put the receptacle on the belly, right under neath, so the cable length is about ten inches. Yes, it weighs a couple of pounds. The battery is not easy to access (Odyssey battery, no normal access required), and I have had to jump start twice when I had run things down when demoing the EFIS to folks for long periods of time. (I learned my lesson, and now hook up the external power before doing that!)

Paul

[f1rocket]

I have never installed one......but I wish I had. I've had a couple of instances where I've need to jumper the battery. Install it close to where your battery is located to minimize the wire runs.

[rv8ch]

If you plan to need a jump start pretty often, then the big honkin' piper-style connector is good. If you only plan to charge the battery, then a charger on a cigar lighter-type connector should be enough. That's my plan, but I have an electrically dependent engine. If I can't start for some reason, I'll stay on the ground until I know that both batteries are fully charged.

[Vern]

Yes-install one, but it could be a much smaller lighter design.You might even make one with a Clothes dryer plug or something similar.

My 6A with Odyssey battery is on battery #2 with still less than 100 hrs. I put a 'battery keeper' small charger on the battery terminals to top off the battery when I've been playing with electricals in the hanger but I've still needed to use a regular battery charger several times in the last few months when the keeper would not recharge the battery.

An external receptical would make life so much easier.

[atreff]

After being stranded many times in my '66 Mooney that did not have a gnd power recept, I vowed to put one in the RV-8.

I mounted mine on the rear baggage floor.

I also did the overvoltage/reverse polarity getup per Bob Nucholls:

http://www.aeroelectric.com/articles/grndpwr.pdf

Enjoy,
Art

[fodrv7]

Scott,
I too, installed one on my -7.
I have used it at least a dozen times as a builder, but not yet as a pilot.

During construction and Electrical fit out it proved indispensable to be able to leave the Master switch on and have the ground power connected to a battery charger.
If you are fitting EFIS, VHF with memory freq and Transponder you will be sitting in the cockpit for with the master switch ON for hours whilst you set up the systems.
I plan my first long trip to the Outback next month, so I will spend a few hours loading the Flight Plans into the GPS (GRT in my case) before I leave, with the Master Switch On and the charger connected.
However, the prime reason I fitted Ground Power, is that I don?t fancy trying to Prop Start a fuel injected IO360 with high comp pistons in the middle of the Australian Outback. I?ll just flag down the next passing FWD for a jump start.
If you plan to go ahead, email me (rvseven@bigpond.net.au) and I shall send you some pics and a description on how I did it on my ?7.
Pete.

[gmcjetpilot]

I vote for NOT. I DO think you should have access to charge the battery but not jump a dead battery to start.

I don't have the same experience of others needing multi jumps all the time, at least in my RV. Some one needs to learn how to turn the master off. The one boo-boo where I drained my battery, I just charged it before flight, which took a little over an hour. I would rather have a fully charged battery to start a flight than a dead one, especially now a days with electrical dependant panels and engines. I am never in such a hurry or MUST FLY situation that jumping makes sense to me. This is pleasure flying not national defense fighters on standby.

If your battery is so dead, do you think it wise to jump a dead battery and than jump in and go fly?

I DO suggest having direct electrical access to the battery for charging. That can be done with a little plug reachable thru the cowl oil door or from inside the cockpit, either thru a cigarette lighter jack or some plug you can reach under the panel. The wire gage can be fairly small, say 18 gage to handle the charging which will be much less than the 100's of amps to jump a plane. That's just my opinion. A Piper Jack is a big whammer jammier, heavy and also not cheap I recall.

I just don't buy the NEED for a jump jack on a little plane. A good battery can run the panel for pre-flight and than start with no problem. If the battery is dead all the time or need to jump your plane often, you have other problems. I personally don't think you will get your moneys worth out of it. In my opinion it's not worth it for the one time every 5 years you might need it, if you are unlucky or really careless with the master switch. If you don't forget the master you will eliminate the prime reason for dead batteries in aircraft. Put in a waning light or buzzer if you must. When planes had rotating beacon's on the tail I left it on all the time. If the master was on it was on. That way walking away from the plane you could look back and see if the master is on.

Wheather to install a jump jack is both an option and an opinion, with no right or wrong, but consider the added weight and cost. It's not only the weight of the jack it's the weight of the large gage wire and terminals.

Electrical schematics which do incorporate a "battery/starter jump jack" incorporate an isolate solenoid (relay), a large heavy contactor. This is actually a good idea. It isolates rest of the electrical system, like the avionics, from the battery and jumping power source when you connect anything to the jump jack. WHY?

I know of many cases of battery jumps gone bad. When Mr. Ramp Boy hooks up that 24 volt battery cart to your 12 volt plane or reverses polarity, causing massive damage, you'll know what I mean. It's happened and will continue to happen, all the time. You can be careful and always supervise the procedure, but it takes at least two people to jump a dead plane safely. You are opening yourself up to error. There's a big differnce in hooking up 6 amp battery charger and a battery that can provide 300 to 1000 amp surge. I am just not big on jumping, as you can tell.

Just be careful if you do jump your plane. The location of the Piper Plug fwd of the firewall thru the cowling makes sense for the RV-7/8 and 9, because the battery is on the forward side of the firewall. You can put plug anywhere but it requires longer and heavier cable runs. Its dangerous working around a spinning prop, including hand prop accident (which I am not a big fan of on high compression engines).

A better place for the JACK is behind the wing, but that's a long (heavy) battery cable if you leave the battery on the firewall. There have been tragic accidents of ground personal involving electrical jumps of planes, all sizes and types. In one case a pilot tried it solo and ran into the prop. If things are not near 100%, I am not flying, but that is just me.

[f1rocket]

I can think of several instances where charging a low battery and flying is perfectly acceptable. Now, if your battery is chronically dead, I agree with George, you have other problems.

BTW, connecting up a mini-charging system is an excellent way to short out your entire electrical system. If these wires short for some reason, you'll bring down the entire electrical system. I think that's one of the reasons for the extra solenoid. It is also there to protect your system from the charger too.

I agree that it is more complication and weight. But if you're going to do it, I'd follow Electric Bob's suggestions. They appear to be well founded to this electrical dummy.

[fodrv7]

Hey George,
Hard to get 240volt power for your battery charger here.
But if you wait a day or so, a Landcruiser should appear in a cloud of red dust.
Pete.