I read most I think of the old posts on underseat batteries, and am trying to understand the advantages - compared to a lighter weight one to replace the original in the tail.
As I can tell, the underseat batteries allow a shorter cabling run, and hence can deliver more starting amps?
But is the disadvantage that you have moved the weight forward for balance reasons?
Is there a preference for location on a 150/160 cub?
And a preference on 180hp cub?
thanks,
The under seat advantage is shorter cabling and easy to charge or jump start.
theres lots of good reasons to move your battery, first getting ride of your gill 25 or 35 wet servicable led acid boat anchor @ 29lbs for a sealed oddysy battery @ 13.5 lbs that can be sent any wheres in the us mail non hazmat, & cheaper to replace! shed about 8' of heavy starter cable & battery box, shelf ect, Atlee makes the best under seat bracket out there but dans aircraft has the whole nine yards in an stc'd kit, your battery is now under the pilot seat. more fwd c/g ( liter tail) & it's getting some cabin heat ! easy to charge or jump or remove.its also a lot stronger of a battery I love mine.
those who hesitate shall inherit the earth.
For me, it’s more of a package of parts.
Along with the under seat battery, I replaced the starter with a lightweight B&C gear reduction unit and replaced the stock copper/brass Harrison oil cooler with a lightweight Niagara unit. The combined effect of these parts retained the original cg location.
I also replaced the stock two fuse system with a single 35 amp breaker that’s easily accessible by the pilot.
The end result is a permanent loss of about 25 lbs, longer battery life, faster cranking, cooler running, a more user friendly electrical system, and a net gain of about 1000fpm climb.
Ok, I’m lying about the gain in climb but, the rest is true.
It’s a package deal.
I concure with Lawn Dart! but dude ! got a 2000 ft climb rate! sum ting wong? .....I jokes...
those who hesitate shall inherit the earth.
In milder weather, not as worried about the cranking power, would you instead just put a lighter weight, more modern, battery in the original location - plus do all those other mods suggested (lighter starter, etc) instead of going underseat?
These new technology batteries really crank the engine over when combined with one of the new light weight starters. If you've ever cranked an engine over untill the battery went dead, you will like the new setup. So many areas of the Super Cub have improved since the 50's and 60's, this is just another one of them. Navigation; compare a Garmin 296 to an old Nav/com or ADF and that is how the lead acid battery compare to a new dry cell battery. Take care. Crash
Here’s my take on it.
All of these planes are a little different so you’ll have to do your w/b calc prior to purchase.
Check the Type Certificate. Certain batteries are certified in certain locations. The new smaller batteries aren’t certified in the stock location (that I know of).
If it’s not TC’d, TSO’d, STC’d, PMA’d or otherwise BFD’d, can you get FA'd? If not, you may feel like you just contracted STD’s.
If it doesn’t blow the regs, or blow your cg out the front of the graph, what’s the harm in going modern and lighter?
I have helped take out the old battery from its location, and install the new ones under the pilots seat. Very clean neat set up, I like it. I know it shortens the battery cable alot. As far as I could tell, jump starting would be a little hard. its laying down and the seat is close to it and the solenoids hide the battery posts. Maybe Im wrong, but it seems pretty tight under the seat for jumper cables. I did stop by CubCrafters awhile back and they are moving the battery under the back seat. Just lift the seat up and there is the battery posts looking right at you next to the door. This would help the C.G also. It only saves about 2' of the battery cable from what I could tell.
Bill
Warm batteries charge better. Cold batteries barely charge at all. Fact.
SB
I think I would prefer to put the gelcel battery under the rear seat, with the under-seat storage box, primarily for CG considerations. I have seen this done on the experimentals. Is there an STC for certifiied installations?
Volunteer, in charge of Political Correctness
CubCrafters have the rear battery installation STC for the cubs, also have a box and lid that covers the battery. Im thinking the same thing for the C.G. Looked like a pretty good set up and easy to get to. It goes right under the rear seat next to the door.
Bill
I agree with everything said so far on the small batteries, except for a couple details:
1) The Hawker batteries, specified in Dan's STC are in fact, tso'd. Therefore, they are an airplane part, by FAA definition. They are also a battery. Therefore, if you want to install one in the original location, in the original battery box, you should be able to do so as a minor alteration, and this should not require a field approval. I've run that by our FSDO, and they are totally on board with it. Your experience may differ, however, depending on which FSDO and mechanic you are dealing with.
2) My experience with these "dry cell" batteries is that they don't seem to care whether they are cold or not, as far as charging goes. I have flown several "brand x" airplanes with the Gill battery in the aft location, as in cold, and we had to use a battery blanket to keep them warm at night, or they'd gradually lose all their oomph over a period of several days, cause they never warmed up to recharge. I've never put any sort of heat to the replacement Hawker batteries, and they chug along in -35 to -40, spend the night out, and still take a charge in the morning. I don't know why, but that's my experience.
3) CG: It is always better to have a forward CG empty. This allows you to load more stuff aft and still be safe (I'm not talking legal here, I'm talking able to control the plane). Having the battery under the front seat is a distinct advantage in that realm. Load some survival gear far aft in your rear baggage compartment, that stays with the plane at all times, and you've addressed the CG issue.
4) I agree that the under front seat battery is a bit hard to get at. But, my experience with these batteries is that they require precisely zero maintenance, so I woulnd't worry about accessability much. If it gets dead for some reason, hand prop the dang thing. Piece of cake, and a skill everyone should know in any case.
MTV
Here's a little reading to explain about batteries such as Odyssey's, which are AGM type. Scroll down to the following paragraph and read about the effects of temperature on batteries. This site is that of the premier solar power suppier on the web. If you're into solar, these guys are a fantastic resource. (I use and am a supporter of solar electricity.)
http://www.windsun.com/Batteries/Bat...at%20Batteries
SB
From Hawker Energy Products' web site:
Additionally, the battery's thin plate technology provides greater cranking power, especially effective at cold temperatures. For example, the PC 2150 has 70% more starting power at -4oF (-20oC) than wet cell batteries, and can start vehicles at temperatures as low as -20oF (-29oC).
They call this a VRLA (valve regulated lead acid) battery, not an AGM type, whatever that means.
And, that is way more than I know about this stuff.
I do know that these batteries seem to be totally happy at very cold temperatures, and maintain their charge, even after having been run in the cold for a week at a time without ever getting warm.
MTV
Another advantage not yet directly mentioned is that rear battery box removal opens up that space for a nice upper extended baggage area.
Also, not sure anyone mentioned what happens when a wet battery dies, freezes, and cracks open. It leaks electrolyte when it thaws.
Anyone mention how a lightweight battery handles an overcharge situation? Not common, but it can happen. When it does, the larger battery would have a heat dispersion advantage due to it's mass.
Everything's a tradeoff. I like the compromises of the lightweight batt. better.
DAVE
Bill - at least according to the Cub Crafter's website their underseat storage box and battery set up are not STC'd which is fine for experimental aircraft but not for certified.
Here's the link. http://www.cubcrafters.com/cci/rebui...eatstorage.asp
Stand your ground, don't fire unless fired upon, but if they mean to have a war let it begin here. - Capt. John Parker, Lexington April 19, 1775.
Gunny
I really like Mike's "take" on the PMA battery issue. Next time the Decathlon needs a battery, I convert! Spilled acid has caused an AD on the aerobatic Champs.
As to jump-starting a Cub? There are a lot of airplanes that are going nowhere with a dead battery; the Cub is not one of them. Get some instruction on hand-starting; it will "go" on the fourth blade. Be prepared for it to start even before you turn the mags on; it happens all the time!
Except on floats.
except on floats....except what? We can't read your mind.Originally Posted by Yard Dart
I had a dead battery when moored in deep water hard to prop a 180 on floats.
The only thing that bothers me about the underseat location is that it represents about 20 KWH of stored energy that could suddenly turn into heat, and as a bonus, is strapped to your butt. Not often, but it would only take once.....
I've had one under the front seat for 5 years, zero maintenance.
Well, sure, but like I said, it would only take once. Has anyone ever even heard of a gill battery or dry battery that suffered an internal short and self-destructed???????????????????????????????????????? ?????
I just encountered paperwork that involves Dan's battery change. The aircraft had a C/G of 72" before Dan did his magic. Then he weighed it, changed the datum to the Leading Edge, and came up with a C/G of 5" - or 65" using the AFM datum.
I have not worked it all out yet, but if I just do the math and pull the Reading battery out without adding a thing, I still get around 7" (or 67). I assume the Odyssey or Hawker will move it aft from there.
But the real problem is if a Cub comes out with an empty C/G too far forward, it becomes difficult to operate under normal conditions. I assume Dan's scales are ok, but he apparently missed the real problem.
we had one guy flying in bad snow squall and pucker down in seat so far as to short a seat spring to battery... he was quite stinky when he landed back at airport still, battery was all melted, bottom seat cushion was partialy burned.. luckily it was winter and he was on skis and just sat it down where he was.... of course he was kinda depending on the gps at the time the electrical went out....
The only thing that bothers me about the underseat location is that it represents about 20 KWH of stored energy that could suddenly turn into heat, and as a bonus, is strapped to your butt. Not often, but it would only take once.....
since then we never leave bottom seat springs in when doing under seat battery, always do a .050 2024 T3 hinged lid....
I gave it alot of thought since I made a few posts on this subject, where to put the battery. My plane has a stock battery that gave out, located in the stock position.
I bought the Odyssey battery. I already have a new Atlee under the seat bracket installed when I bought the plane. I talked to everyone I could about it and seen several under the seat Odyssey's with the relays installed. I left the original battery box in and also in the stock location. Installed the Odyssey battery in that box. Installed the light weight starter and it works great. Really spins that motor over. To jump start if needed just remove the battery cover on the tail of the plane, put your ground clamp on the ground bolt from the battery to frame. Then the hot jumper on the solinoid terminal (hot side of Battery) Jump in and start it. Easy. Most important to me was the weight thing, CG Lighter on nose and still some weight on the tail. The battery is so easy to get to this way. Next I will put a Borer prop on, then a Baby Bush wheel on the back, again more tail weight. I agree with Mivion about the CG. But also listen to other cub driver's about keeping some weight back to keep from going over on its back in the rough stuff. Just my own way of thinking
Bill
If I had to pick one plane, it would be the Super Cub. Im going to build one and try to find a 180 to put in it. I will need your help. Thanks
Mike:
The Odyssey is on its side. How did he short it out?
Bob:
There is no published empty weight CG for a Cub that I know of.
Thanks TJ - that is what the type certificate says, but at 5" you cannot legally fly the airplane with most normal loads. Maybe with a Moose in back . . .
Turns out that Dan had reasonable scale numbers, but when they were applied to the Piper equations shown in the AFM, There was a significant error. That is easy to document, and gives me an excuse to say the entire process was flawed. Then I compute all the changes from factory numbers and come up with a lighter aircraft that can be flown with any legal load, including single pilot no ballast.
Now I need some help: Does anybody know how much an AmSafe inertial reel seatbelt setup adds to the weight?
How about BLR VGs? I can find out Monday, but as you can see, I am closing in on the correct answer to my latest problem.
Yahoo!
he got the seat spring pressed down to positive post, and boy was that spring long after it cooled off from shorting out, straitened it a bunch!... also this may have been pre odyssey when we used those same size black sealed lead acid ones from frigid north... but i seem to remember the melted orange battery in my mind....
I put an O360 in my cub last spring with the stock battery location. We checked the weight on floats with certified scales and the CG is at the forward limit with just the pilot. For my cub the under seat battery is not a good choice. I have a lightweight starter, rear mount oil cooler. To help get keep the CG back, I always take some survival gear, and it goes back as far as possible.
Last edited by M1; 12-11-2010 at 09:45 AM.
Five years ago MVivion wrote this...
"1) The Hawker batteries, specified in Dan's STC are in fact, tso'd. Therefore, they are an airplane part, by FAA definition. They are also a battery. Therefore, if you want to install one in the original location, in the original battery box, you should be able to do so as a minor alteration, and this should not require a field approval. I've run that by our FSDO, and they are totally on board with it. Your experience may differ, however, depending on which FSDO and mechanic you are dealing with."
Did I read someplace this has been reinterpreted in the last few years and requires a field approval now? That would be a shame.
Aviationinfo
the odyssey (same?) is pma'ed for a PA-18, but had to get a field approval to use it in a scout a few years ago.....
If you fly around lightly loaded by yourself I would leave the battery where it was originally. It moves the cg way forward which if you are always loaded is great but if not you are nose heavy. It all depends on your mission and how you load the plane.
I install the Hawker battery in the stock battery box with a 1" wide .032" 4130 strap and two AN3 bolts. There is an STC to install it in the Pacer and Tri-Pacer battery box which is the same as a Super Cub box. I make a simple log book entry and weight and balance revision.
Steve Pierce
"When everything seems to be going against you, remember that the airplane takes off against the wind, not with it."
Henry Ford
Hawker is/was the manufacturer of Odyssey batteries. Same same. The SBSJ-16 battery used to use the Hawker name while the non-PMA version used the Odyssey name. I think they're all using the Odyssey name now. Hawker/Enersys/Odyssey makes several approved aircraft batteries but for small GA planes the SBSJ-16 model is the popular one. It's PMAd for PA-18/19. Approval in other small planes has been easy. I believe Burl has an STC for that battery on the firewall of a Cessna 180. Lots of 180s have field approvals for Odysseys other than the SBSJ-16 model, too.
In any case, the advantage of moving the batteries forward? Odyssey batteries are small and light and can be mounted in any position other than upside down. That allows installations in places previously unavailable allowing for much shorter cable runs. Like under a seat and on a firewall. Both are great options.
SB
Last edited by StewartB; 12-11-2010 at 08:29 AM.
My understanding is that the FAA-PMA approved version of the Hawker battery is actually used in some transport category airplane as a backup to the backup, and this is where the PMA came from. It is STC'd in the underseat location of the Super Cub by virtue of Dan's modification. PMA simply means it's an airplane part. You still have to have some basis for installation, IF you're moving the battery.
I've had both done: Installed in original location as a replacement battery, and installed via a Field Approval. So have folks down here. The only kink I've heard of is when trying to install a battery in other than the original location, which will likely require an STC nowadays, and the fact that some airplanes may not be able to use the small battery due to load calculations. Depending on whether the airplane is a part 23 or CAR 3 airplane, that may or may not be an issue.
MTV
with my survival gear that stays in my cub,i don't have to worry about the battery weight forward,if ya'r flying around even in the lower 48 without even the basics,ya'r not thinking,imho!!!!
jr.
I am getting to the almost done point. At first, I thought the battery change had rendered the airplane unflyable without a moose back in the back, but I found one giant math error and two smaller errors, all of which move the center of gravity aft. It is now a normal airplane. Three times during the computations I got sucked in to using the leading edge for a datum, and I know better.
The AFM uses 60" forward, but then it gives you an envelope graph based on leading edge, and an equipment list based on the same thing. Every single Cub weight and balance I have ever looked at had at least one small item using the wrong datum, and some even have the gear in the wrong spot, by as much as 4 1/2 inches! That shoots you in the foot, if you are weighing the thing.
the W&B guy here gets like $250 I think. to weigh it and make up a new equip list and whole beautiful booklet with type cert, loading graphs, etc. and laminated erasable loading cards for your seat pocket.... we used to fly him out to naknek 20+ years ago and get a bunch of airplane people together to defray the trip costs....(he also dyn balances props)
so if there's much question or changes its usually cheaper to have him come reweigh it....
plus when you get ramped and you have that all current... um....
The T.C. for the 18's and 22's calls for a Reading battery only. Enyone ever seen one? I never have in the 43 years I have tweaked on them. Ran into a problem of using a Gill battery in a 22/20 during a recertification. The FAA would not sign off until 337 Field Approval was issued. As far as I know around here, that is the only legally installed Gill in our local Cubs and Pacers, and there are a lot of Gill and Concords running around in these planes.
Steve
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