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Underseat Battery Installation.

kiwicubber

PATRON
Te Kowhai, New Zealand
I have just purchased the Attlee Dodge kit for under seat battery, and the instructions are to route the wires IAW AC 43.
Just looking for ideas where to mount the battery solenoid?

cheers Bill
 
Kinda like this. My Firewall Atlee installation
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Mount it and starter solenoid on a plate in front of the box between the seat legs. Someone should have a pic.
DENNY
 
Mount the master relay on the front, center, lip of the tray. Route a 4 gauge battery cable down under the floor. Bring it out from the floor between the boot cowl and kick panel on the left side. Clamp it to the fuselage tube that angles up to the top engine mount fitting. What I do here is fabricate a bracket to hold the start relay to the tubes. Then route more 4 gauge cable from the start relay, out the firewall hole that uses the phenolic chafe strip, and on to the starter.

Web
 
4 gauge? Thanks- I was just going to look to see if I could find the specs for how many amps a typical skytec/b&c loghteeight starter pulls, as I’m doing this mod now and getting ready to order wire...
 
If you leave the battery back in the stock position, I'd stay with 2 gauge cable. But under the seat, or farther forward, 4 gauge works well. Shorter cable length allows use of smaller cable.

And be sure to put spike diodes on all of your relays. Your avionics will thank you for that.

Web
 
I went with 4 ga on my firewall installation.


If you leave the battery back in the stock position, I'd stay with 2 gauge cable. But under the seat, or farther forward, 4 gauge works well. Shorter cable length allows use of smaller cable.

And be sure to put spike diodes on all of your relays. Your avionics will thank you for that.

Web
 
This photo ought to give a general idea of what Web was referring to:

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Here’s a good way to route cables thru the floor.
piper bulkhead isolators.
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I install the master relay directly on that forward, upturned lip on the tray. The steel is plenty strong and there is plenty of room for the head of the screws. Just cut a narrow piece of P-tex or phenolic chafe strip and drill clearance holes for the screw heads. Another advantage of the single, master relay on that lip, is that it still leaves room for the brake masters.

Web
 
It does get a little busy under there, brake resivours must be considered if you are going this route:
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I just installed Atlee's under seat battery tray in a flying Super Cub. It was a late model airplane so it had both the starter relay and the battery master relay and I mounted them like the pictures posted above. I ran the battery cable down the left front seat tube, under the flap handle and attached to the diagonal tube that goes up and forward from that cluster. Since the electrics are still in the right wing root I ran the power wire through the hole in the floorboard for the brake line and up the tube forward of the door opening to the windshield post. I trimmed the interior panels for clearance of the wires and used spiral wrap, wire ties and Adel clamps to route the wires and eliminate the chance of chafing.
 
The only one I have seen is like that. Seems to work fine, and battery replacement/brake servicing is not difficult. But it is on an amphibian. I would think that the first thing one would do when installing Wips is move some weight aft?
 
I have been installing the solenoids in tandem above the torque tube... starter on the seat frame, master on the battery tray... this makes it a lot easier to service any style brake master cylinder installed...

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Aluminum bracket pop riveted onto the seat frame for starter solenoid...

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Bracket is bolted via adel clamp at the bottom...

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Solenoids installed..

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This one has a set of my master cylinders installed...

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Battery and wiring...

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Top view... note the access to master cylinders is improved by this setup...

Brian


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How many folks are leaving the springs in vs the hinged plate that comes with the STC kits?

Any issues with springs contacting anything of concern?
 
Talked to a couple of customers that have had the springs connect with 'hot stuff'. I highly recommend fabricating a solid aluminum panel to serve as a seat bottom, in place of the original springs, any time you have electrical items under the seat.

Web
 
How many folks are leaving the springs in vs the hinged plate that comes with the STC kits?

Any issues with springs contacting anything of concern?

do NOT leave springs in... they will short out on battery in flight... Like web said above know of a guy had his short out in flight, scud running using gps, the the seat shorted out melted the battery & seat no electrical system/gps then, seat was one of those sleeping bag ones... almost cost him his plane.... and STINK!!!!! luckily he was on skis and it was winter and he landed quick and got it out...
 
…. I highly recommend fabricating a solid aluminum panel to serve as a seat bottom, in place of the original springs ….

Has anyone used Ceconite for a seat bottom, a la BAS Cessna jumpseats?
The little bit of give they have is a little more comfortable than an aluminum panel.
 
I covered my front seat bottom and the backs of front and rear seats with fabric about 9 years ago. So far, so good.
They're pretty light.
 
I have heavyweight Stits on mine. Works great. You'll probably want a bit stiffer seat cushion bottom.
 
Has anyone used Ceconite for a seat bottom, a la BAS Cessna jumpseats?
The little bit of give they have is a little more comfortable than an aluminum panel.

I did before I moved the battery. It is really a pain in the ass to take the stick out, and take the front seat out to access the battery. With the metal plate you can take the cushion off and flip it up to access the battery


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Years ago there was a Cherokee 140 near here which had the back seat option. The springs on that seat squashed down enough to short out the battery and start a fire. This isn't just a Cub hazard.
 
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We had a PA14 here that a previous mechanic and cleaned up and painted the battery box on. He forgot to reinstall the wood blocks and as we were towing the airplane to the work hanger the battery contacts contacted the lid and shorted out causing a fire. Got the interior and the instrument panel and glass. Pretty scary.

I can't imagine servicing the battery under the springs or a fabric seat bottom. I have always installed the hinged seat bottom.
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