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JUMP STARTING

A

Andrew Hamilton

Member
Not so much an RV-7A question, but all RV's with the battery on the LHS of the firewall.

Due to the time involved in removing the cowls I was thinking of placing some remote battery terminal posts possibly fastened to the engine mounts below the oil filler door.

Couldn't find any posts on the subject so was wondering has anyone else done something similar.

If posts were mounted below the oil door they could be easily accessed for the new mini jump starters that are now quite common.

Remote posts could be fabricated or bought as parts from the many cars that have a similar thing when their battery is placed in the boot/trunk.

I have enough suitable cable left over from the build so am wondering if there is any reason not to try this.

My thought was to run the positive lead straight from the battery but maybe the negative lead as an earth from the engine as it is closer.

The posts could be suitably capped when not in use. I think these points could also be used for charging the battery too ?

Would appreciate any thoughts on if this sensible and the best way to go about it.

Cheers,
Andrew Hamilton
Australia
RV-7A
 
Good question Andrew and I am sure you will get an opinion of an engineer. I jumped my airplanes a dozen times over the years. I used the battery of my and jumping cables from autoparts store. The stock cable can't grab the positive terminal bolt the clamp is too thick and clumsy. Using a Dremel tool I filed the clamp and cut little teeth for better grab. I also wrapped the positive clamp with insulation tape in case if it slips it doesn't shorten on firewall or battery box cover.

Edit; I fit the jumping cables through the oil door. They have to be long enough and they have to be secured (I tape them to the cowl). Otherwise the slip stream and engine vibration will create inconvenience :)
 
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Tony Rome said:
Attached below is a link to a EAA web video. It describes a method to solve a dead battery issue. Actually, it's pretty clever.

Best,
Tony

http://www.eaavideo.org/video.aspx?v=1009394733001
Click to expand...

I watched the video and would not recommend doing this. Mixing common AC plugs with hard connections to a battery is asking for someone to figure out how to plug your battery to AC power.

There are hundreds of options to do this using unique connectors that will not be mistaken for something else.

Carl
 
I feel the same way. That 14AWG cable is marginal for a jump start.

I bought a piper style power socket and wired it directly to the battery with the appropriate guage wire. The piper plug is concealed behind a used cessna oil access door glassed into the bottom of the engine cowl near the battery.

Also bought a set of jumper cables to match for 1/2 price on ebay and carry those in my bag of tie down equipment.

I've had to use it once already. Very easy and safe to get to it.

Bevan
 
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Incredible! DANG! WARNING! I did this two weeks ago and did not see this vid but did the exact thing, but I hooked up the male plug to my NEW high tech LI ION battery charger.......can you see where this is going.....so the next day I walk in the garage and thought I would charge my new battery and so I plug in my new set up and POP! plugged in the 12 v DC output into the wall.......there goes 150.00
 
Carl Froehlich said:
I watched the video and would not recommend doing this. Mixing common AC plugs with hard connections to a battery is asking for someone to figure out how to plug your battery to AC power.

There are hundreds of options to do this using unique connectors that will not be mistaken for something else.

Carl
Click to expand...

I don't know that I completely agree with this. I do agree with the other comment that 14AWG wire is not good to jump it with, but it is good enough to charge it with then start the engine after it's charged. The way he does this uses the female on the battery side. Unless you have a hardware store that sells male-male extension cords, you can't accidentally plug it in wrong. It's actually a very simple and clean way to charge it up IMHO.
 
FWIW, charging a dead battery is pretty hard on an alternator, and in the hazards of flying on a already dead battery and charging is probably a better option.
Tim Andres
 
tim2542 said:
FWIW, charging a dead battery is pretty hard on an alternator, and in the hazards of flying on a already dead battery and charging is probably a better option.
Tim Andres
Click to expand...

I agree.

In my shop, we will only resolve a no start problem by charging the battery long enough that the engine will crank and start on its own. That usually gets it charge enough that it is not a huge charge current from the alt. to the battery after the engine starts.
 
Charging cord

I use a polarized dc plug that matches my trickle charger on the end of a 12' piece of 14 gauge duplex stranded wire. Color coded clips on the other end. The short pigtail with the matching polarized plug is near the oil door and power goes thru a 10 amp, self resetting RV breaker. I made two of these up so I have no excuse not to have one with me. Actually charged up battery one time from a groundskeeper's riding lawn mower in the time it took us to walk over to a bench, talk about airplanes and politics and then walk back to start the plane. Never even attempt to crank with it connected. Just top it off for 20 minutes or whatever it takes. Works great for me.
 
Jesse said:
I don't know that I completely agree with this. I do agree with the other comment that 14AWG wire is not good to jump it with, but it is good enough to charge it with then start the engine after it's charged. The way he does this uses the female on the battery side. Unless you have a hardware store that sells male-male extension cords, you can't accidentally plug it in wrong. It's actually a very simple and clean way to charge it up IMHO.
Click to expand...

I've seen many less than sailor proof setups get used wrong and this one screams "go ahead - try me". Why do this when there are simple and better options?

As far as jump starting, I'm in the camp that a jump started airplane is less than safe as there is no telling if you killed the battery, or how long you will fly with little to no battery reserve. If the battery needs to be charged, charge it. If you abused it and it does not hold a charge, replace it - then go fly.

Carl
 
While I largely agree with Carl's statement above, one must understand there are some circumstances where a jump start is the only option available. This particularly applies to remote locations where no charging facilities exist (I can think of quite a few places I've flown that were several hundred miles from the nearest 115VAC outlet...).

Having the ability to jump start the airplane without putting ground crew at undue risk is a great idea. I haven't yet decided on a solution for our particular aircraft but am leaning towards a Piper-style plug on the underside of the engine bay, likely mounted such that it would be accessed through the cooling air exit area. This would make it easy to carry a mating plug in the aircraft with large alligator clips to allow attachment to a battery or booster cables. To reduce the risk of shorting I would employ the super-easy technique of having the (+) and (-) leads cut to different lengths so the alligator clips cannot make physical contact with each other.
 
Carl Froehlich said:
I watched the video and would not recommend doing this. Mixing common AC plugs with hard connections to a battery is asking for someone to figure out how to plug your battery to AC power.

There are hundreds of options to do this using unique connectors that will not be mistaken for something else.

Carl
Click to expand...
He's showing the female end to be left with the plane. Going to take quite a bit of effort to have someone accidentally connect a male-male 120 volt extension.

Personally, I use a 12-14 ga set of custom jumper/charging cables. Large alligator clips on each end. Connects to the battery though the oil door. I've used it 10-15 times over the life of the plane. It stays in my AC tool bag.

BTW, leave the strobes on all the time. It'll help prevent leaving that master on.
 
I would still be careful with those cables, it is still possible for those cables to short on each other. All that is required is for the longer one to have a loop or fold back on itself to use up the extra length so that the normally longer one can still touch the shorter one.

I always clip the ends to the middle of the cable somewhere.


Canadian_JOY said:
While I largely agree with Carl's statement above, one must understand there are some circumstances where a jump start is the only option available. This particularly applies to remote locations where no charging facilities exist (I can think of quite a few places I've flown that were several hundred miles from the nearest 115VAC outlet...).

Having the ability to jump start the airplane without putting ground crew at undue risk is a great idea. I haven't yet decided on a solution for our particular aircraft but am leaning towards a Piper-style plug on the underside of the engine bay, likely mounted such that it would be accessed through the cooling air exit area. This would make it easy to carry a mating plug in the aircraft with large alligator clips to allow attachment to a battery or booster cables. To reduce the risk of shorting I would employ the super-easy technique of having the (+) and (-) leads cut to different lengths so the alligator clips cannot make physical contact with each other.
Click to expand...
 
Jumper cables

I was in the marine supply store today and saw the perfect setup. They have jumper disconnect pigtail kit for a trolling motor setup. 10 gauge Cable with nice polorized connector. Connect the ring terminals to the battery near the oil door and then splice on some 10-12 gauge duplex cables to some alligator clips for the battery. I think I will buy a couple of these to have a spare. Again, charge only, don't crank the engine on it.
 
"I would still be careful with those cables, it is still possible for those cables to short on each other. All that is required is for the longer one to have a loop or fold back on itself to use up the extra length so that the normally longer one can still touch the shorter one."

Steve - as you've so accurately pointed out, care is ALWAYS required when using jumper cables. Nobody likes it when a simple boost turns into a light show! :) This "one short, one long" technique works very well when the difference in lengths is just a bit greater than the length of the typical booster cable clamp - say 8-10 inches. I used to make these up for the fly-away field kits for the helicopter fleet I was supporting. I likely made up 60 or so of them and they received rave reviews from the field crews.
 
I left my master on at a remote airport early this spring and when I came back to the plane a few days later, It was dead. I have a female 1/4" phone plug installed into the lower firewall lip. I filed a notch out of my cowl so that it slips over the plug. It is wired direct to the battery and is fused with a 30 amp fuse. I carry the male 1/4" phone plug in my toolbox in the plane. I inserted the plug and hooked up battery cables to the plug and the ground on the exhaust stack. I let the car Idle about 30 min and it charged the battery good enough to start the plane. Not possible to jump start because of the fuse. Fortunately, it appears my Odyssey wasn't damaged noticeably.
 
Jumper and Charge Cable

I purchased a female Piper type aircraft fitting from Aircraft Spruce. I connected the positive central connector to the positive terminal of my Odyssey battery, using the same gauge cable that I used to the starter motor. The charge receptacle was attached to the engine mount next to the engine oil filler.This was done with a fabricated bracket and 2 adel clamps. The earth part of the receptical was was grounded to the the common earth at the firewall.
When I open the oil filler door , I can either charge the battery or jump start the engine using a fabricated jumper lead set which has the complimentary Piper male fitting attached.

The female fitting inside the cowling is protected with a spring lid so no foreign objects or oil will short out the terminals. The system works well with almost no risk of shorting the system and enables easy battery charge after software upgrades on the ground.

I adopted this system whilst building this plane , having had very poor access to the battery in a previous RV6. I' borrowed' this idea from a fellow builder.

Jeff Rowlands
RV7A
Mansfield. Australia
 
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mr.sun said:
I was in the marine supply store today and saw the perfect setup. They have jumper disconnect pigtail kit for a trolling motor setup. 10 gauge Cable with nice polorized connector. Connect the ring terminals to the battery near the oil door and then splice on some 10-12 gauge duplex cables to some alligator clips for the battery. I think I will buy a couple of these to have a spare. Again, charge only, don't crank the engine on it.
Click to expand...

care to post a picture or a link?
 
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