to install Piper style ground power receptacle or not?

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

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

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.

For jump or charge?

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.

Jumper

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.

I Vote yes

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

Invaluable

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 ([email protected]) and I shall send you some pics and a description on how I did it on my ?7.
Pete.

NOT

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.

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.

Outback

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.

Good point

Peter and Randy you all make good points. I never thought about shorting the electrical system with a charger. I always had the rule of NOT leaving the battery charging unattended. The other point about shorts causing damage has me thinking. I never was comfortable running avionics off a el-chepo battery charger. All battery chargers are not equal. Some do have short, reverse polarity and many other protections afforded microprocessors in the better chargers. I guess the lesson is know thy charger.

I am not anti-Jump Plug, just presenting the CON to putting one in. Really the down side is weight and cost. Otherwise I can see IF you needed it, IT could be a real nice to have.

Also if your alternator is weak, it might roll over and die if you demand it charge a discharged battery. Just keep that in mind. A real dead battery will demand as much as the alternator can put out.

One student pilot I had did a solo cross country and made one small boo boo. She forgot to turn the alternator on. It was a mighty C-152 and she just split the master switch accidentally. She noticed it 1/2 way to her destination as the battery discharged and turned the ALT on. However with the battery now charging and drawing A LOT, plus the radio, transponder, lights on, she pop-ed the CB, twice. Well from then on she did everything perfect. She did not try another CB reset, did a 180, shed load and landed back at the departure airport. Of course if she would have shed load first before turning on the alternator, to let the battery charge a little first, before bringing the other stuff back on line, the CB would not have pop-ed. Hey it was part my fault, I did not know to teach her that and never thought the alternator could pop the CB under normal output. It did. I guess the alternator output CB is under sized, which is not uncommon. SO IF YOU JUMP, let the engine run a little time at higher RPM than low idle. Charge the battery before loading on the other stuff.

And I think the real risk exists when you don't have a charger attached. At some point, the small wires coming from your plug have to get connected to the battery. Even if you use an inline fuse or circuit breaker, you potentially can unleash all the power of the battery through this circuit should the power wire short. It would create a fair amount of smoke as that wire burns. I think that's why the battery charger solenoid is so important.

Protection

f1rocket said:

At some point, the small wires coming from your plug have to get connected to the battery.

Click to expand...

That's a great point and it applies to anything connected to the battery. I DO think 18 awg wire, with an in-line fuse, say 10 amps, is pretty safe. That is what I have. If the 10 amp fuse is right next to battery, you will not smoke the wire (82 amp fusing) since it's whole length 100% protected. Shorts are not good anytime on any wire.


Chargers and charging safety

Charger wires should be fused. Some cheap chargers don't have fuses in their external connector wires, but that's easy to solve, put one in. Many of the new chargers are excellent and now have microprocessors which shut down if there is an internal battery short, which could cause an explosion. Of course they also shut down with a wiring short, but still I would not just leave it hooked up unattended.

Charging batteries do have risks, no doubt about it, but you can mitigate that risk with some care, common sense and good charger. Same with jump starting a plane or car, there are precautions.

Clearly you don't want to run extension cords and wires all over the wing, cowl and canopy. A little common sense is good. The Fire Marshal who inspects the hangers will not allow extension cords to be connected in unattended hangers. You can use them temporarily. I follow the same practice at home I unplug all extension cords in the shop when not there. It is easy to understand why. I know many use trickle chargers and leave them for days on their bikes, cars and planes. probably OK but there is a chance of fire.

Some recommend you remove a battery if it needs to be fully charged. They do blow up on rare occasion. If you bench charge make sure you protect your eyes. I consider charging in a vented plywood box. Here is a good charger that does AGM (absorbed glass-mat or SLA - sealed lead acid) with short, reverse polarity and over load protection.
http://www.batterychargers.com/details.cfm?prodid=SSC-1000A&catid=2

The above is a bit of overkill for trickle charger, but if you do get a trickle charger, max volts for a PC680 is 13.6 volts for extended trickle charger. Typically these trickle chargers only put out about 1.25 amps. This is NOT enough to deep charge a battery but just maintain a charged battery. If you have a full charger that does not cut back automatically to trickle charge (13.6 volts) you must manually disconnect it from the battery. It is not suitable to leave connected for more than say 1-2 hours depending on the charger. These chargers can be used to charge but you must monitor them and turn them off manually. Again I would not leave any charger unattended, at least for an extend period. All the above is for new SLA/AGM batteries, not flooded lead acid batteries, which have different requirements. The above charger will also charge your car battery or deep cycle marine bats.



RISK of ELECTRICAL SHORTS

If you install a JUMP PLUG and connect a 2 awg wire to the battery, running it all over the fuselage with no protection that is a welder. A 18 awg with a fuse adjacent to the battery not so bad.

If we really study wiring diagrams of planes, on many there is often a length of unprotected wire somewhere in the wiring. I know many builders run a wire from the master relay to their battery buss with no fuse or CB. There's wire protection for the items branching off the main buss but not the main buss itself? really true story. It's probably OK if the wire run is short and well protected. The saving grace I guess is you can turn the master relay off if you smell something burning or see smoke.


Battery charger wiring:

HOT wire direct to battery is OK, but if you do run a small wire direct to the battery for a remote charger plug/connection, make sure it's fuse protected (6-10 amps is good), 18 awg wire. Protect and shield from shorts, you'll be fine. You are not tyring to jump start, but just charge without removing the cowl. Even though the RV-4/6 battery is in the cockpit it is hard to get at.

Most chargers are 6-10 amps max, and you don't want anything more 6-7 amp charger for a PC680 SLA battery, which is oddysey's recommendation. If you have a larger battery you may need a 10-15 amp charger. There is probably no reason to go to a larger wire than 18 awg, unless you have real long wire run. I recommend you keep it short as possible, at least under 3-5 feet. Besides the battery, even a drained one, will not pull more than the max amps of the charger, except for the first few minutes of charging. Than the current drops rapidly as it charges, say 3 amps, until when charged and the current is a trickle.