Mounting battery - PC680 and box

[Nathaniel]

Anyone else have the Odyssey PC680? The PC680 and box are bigger than stock and I'm curious how the rest of you mounted yours. In the same position (top of firewall, starboard side) it covers up a firewall pass through, no big deal, I can drill another. But mounting it with clamps seems troublesome. The box has brackets on the side I could easily match drill for screws and anchor nuts. Flush rivet the anchor nuts to the cabin side of the fuselage and screw the box through the firewall to those. It would have 6 screws and be resting on a piece of the engine mount. Sturdy enough? Or does it have to be clamped to fuselage tubing?

I've attached a couple quick photos. You seen in one pic where it would rest, basically the same position as stock except wider. The other pic you can see the through hole I would be covering up and see the mounting holes in the box's brackets. Three down each side.

[jdmcbean]

I do not know of anyone that has used the PC680 and the box in that location on the SS. The ones I have seen have been mounted inside the fuselage.

The stock battery is an AGM battery and box works great and fits nicely. It has been in our aircraft since 2003.

Knowing that you did not have the battery or box with your kit is their a reason you chose the PC680 ? I know it is a great battery.

[Nathaniel]

I have no prior experience with the AGM batteries, so I can't speak against them. All I can say I have high praise for the Odyssey batteries. They seem to be the go to replacement for everything I've ever had that needed a battery. Figure I'd just make the switch right up front and save the hassle of a swap-out in the future.

Looking at the tensile and shear strength of the rivets and screws I'd be using it seems I'm more than covered with mounting it on the firewall. Any "g" forces strong enough to damage the battery box or firewall and those things would probably be the least of my worries.

[Dave S]

Nathaniel,

Passing along a couple thoughts in the form of photos. Our aircraft has 2 of the PC 680 Odyssey batteries - one in the engine compartment and the other behind the seat.

These are slipped into builder fabricated aluminum boxes.

The one in the engine compartment - you can only see the top of it; however, the aluminum fabricated box is secured with the same hardware that the poly motorcycle battery box was that came with my kit (different than the box you have) meaning that cushion clamps are used on the sides and bottom and a SS band goes around the battery with securement above the battery to the firewall.

The one behind the pilot seat is the same kind of aluminum box secured with cushion clamps. Please ignore the two fuel filters in the feed lines from the wing tanks - they are gone now......

Sincerely,

Dave S
St Paul, MN
K7 Trigear
912ULS Warp

[megawatt]

Your battery location setup looks great. I assume GA aircraft have theirs in the same "firewall" location for a reason, strength and CG. I have just purchased a V and the previous owner was installing the battery in the tail. Is the tail an acceptable location for a Kitfox battery? Was the tail location a consideration for your plane? Thanks, Dave

[SkyPirate]

the only reason why I could think of anyone putting the battery in the tail ,..they were planning on a larger/heavier engine ,..I personally still would not put the battery in the tail though,..that means longer leads ..more wire,..if they were light duty wires and a hard start was to take place ..those wires get hot ..
not only that but the way electronics progress,.including batteries ..not all batteries weigh the same ..if it ever had to be replaced,..the different weights of battteries would have a big effect on CG.

was he going to have a trap door underneath the tail to get to the battery?

Chase

[megawatt]

Unfortunately I plan to put in a larger than Rotax engine. I expect you are right about the previous owner planning the same. I can't afford a Rotax. I already have a Lycoming and have been told by more than one mechanic to use it.
Thanks for the reply. My first thought was to your mention of the cable running all the way back and the weight it brings. My next thought is the weight of a "battery" all the way back at a long moment arm during flight operations, much less an accidental spin or spiral. Wouldn't a battery at that location add to a ground loop tendency? Thanks, Dave

[SkyPirate]

well unfortunately ..if a larger motor is used ..CG must be found and applied ..so it's either add a little weight to the end of the arm "tail" or allot of weight closer to the fuselage, as for ground control .. yes ,the less weight at the end of the arm " tail" the less inertia you'll have to compensate for.. a larger motor ..more weight ..in most cases a higher burn rate for fuel ..you've got a good 1/4 mile racer if thats the goal, ( in a racers perspective)..or add fuel capacity,..more weight, to get back to longevity of flight.. also the more weight the less the payload ,..the list goes on,..it is owner/pilots preference as to the type of flying he or she wants their aircraft to be capable of doing,..

Chase

[DesertFox4]

Megawatt, only reason, as Chase posted, to put a battery in the tail is to off set the weight of Continental , Lycoming or Subaru engines. Not sure if you or the previous builder had the wings swung forward to help with the forward CG of the heavy engine. Sometimes both mods are needed to make the CG come out right. I think both are needed for a Subaru.
As far as the flight characteristics , spins ect. I've never heard that the heavier engined Kitfox's have any adverse flight characteristics. I would want a quality tail wheel with good springs for the extra weight like the one John McBean sells.

I already have a Lycoming and have been told by more than one mechanic to use it.

The last part of this sentence is always a clue to the lack of knowledge most aircraft mechanics have about the 4-stroke Rotax engines. Unless they've worked for an FBO/flight training school that uses Rotax equipped trainers , they have no idea of the quality , reliability or economics of the Rotax.

[Nathaniel]

Several builders have also installed the battery behind the left seat. Helps with the CG and it's not all the way in back which can be troublesome for the reasons mentioned.

Because of the bigger battery and box I've decided to wait until I have an engine before I do the install. Started to mock it up yesterday but had more questions than answers, so I'll hold off a bit.