Aluminium lipo boxes (AUS)

[Hyena]

Here comes Mr Asia to tempt you with my latest offer

So, it's no secret I'm a fan of lipo and unless you're a nancy who wouldn't be
I'm also a fan of making a long thin battery box strapped to the top or down tube of the bike.
I've posted before about using PVC down pipe which is cheap and cheerful but it does deform a little and is a tiny bit too tight readily fit most 6S packs, you can't get end caps for them and it's difficult make something that fits due to the pipe flex, thus also isn't very water resistant.

I've hunted around everywhere trying to find the right size aluminium tube and haven't had much luck, until now. I've found a mob willing to make me the size we need for 6S packs 2 wide but I need to order more than I'd care to have laying around at my house for the next little while, plus I figure you guys may be able to make use of it too.

So, it's lipo tube group buy time

Wadda ya get:
Rectangular aluminium tube with an ID of 107x57mm.
Wall thickness is 1.5mm which should be tough enough to survive any crash you get in to. And if you manage to get into a crash that does break the box, damaging your lipo packs is going to be the least of your worries!

This will accommodate 12S or 18S packs or anything else you can manage to jam into the above stated dimensions (eg multiples of 4 or 5S packs)
It will take:
- all turnigy 6S 5000mah packs (15C up to 40C and nanotech up to 70C) with a few mm spare for wiring. (4x turnigy 25C long packs will fit like a glove for a 12S10ah pack)
- all zippy 6S 5000mah packs (15C up to 40C) with a few mm spare for wiring (30C packs will fit but will be very tight on the wiring)

I'm also going to get some end plates manufactured to go on each end. These will be just cut to shape from thin aluminium sheet. Stick them on how you wish - epoxy or screw. For my own ones I'll probably epoxy one end on and epoxy 4 little nuts to the internal corners of the other end to screw into so I can remove it. I could possibly even have L shaped end plates made (eg like on most controllers) for direct frame mounting, though you'd want to use good epoxy on the nuts if they're going to hold the whole thing to the frame...

Time frame: 6 weeks for the next production run.

The cost:
12S length (310mm) $20
18S length (500mm) $30
End plates - $5 (TBC but I can't imagine they'd cost much to get cut)

Let me know ASAP if you're keen. If there's only a few people it doesn't matter but if there's a big demand I'll need to order extra and I need to place the manufacturing order this week.

[adrian_sm]

Interesting. I need to think about this a bit, and sketch up a few ideas on end caps and mounting. If I come up with something good I'll be in.

Are you flexible in the lengths? Or will they all be pre-cut to length for you?

Some of the ideas I have in mind have thicker endplates recessesed in to the tube ends, with CSK screws through the tube wall securing them. This would require the tube to be a bit longer than 310mm.

What sort of internl/external radius will the corners have?

- Adrian

[Hyena]

Interesting. I need to think about this a bit, and sketch up a few ideas on end caps and mounting. If I come up with something good I'll be in.

Cool, I'm open to suggestions if you can come up with something better, I was just trying to think of the easiest option and was thinking of copying basically what controllers do.

Are you flexible in the lengths? Or will they all be pre-cut to length for you?

Nope length can be anything you like (within reason for shipping purposes) I was going to get them to cut a few 12S and 18S sections worth up front and then I'd just have the rest in 1-2 long lengths to cut as required. No doubt their cuts would be neater than mine so the more I get them to cut the better! I also have to be able to get it home so lugging >5m lenths doesn't suit me! I can probably post up to 1m lengths easily through Aus post if you're after bigger lengths

Some of the ideas I have in mind have thicker endplates recessesed in to the tube ends, with CSK screws through the tube wall securing them. This would require the tube to be a bit longer than 310mm.

Yep I thought of something like that but though it'd end up more expensive to have something machined / CNCd and end up costing just as much as the length of the tube itself which people wouldn't be happy with. I'd even be happy with plastic plugs if something the exact size was available.
Eg;

What sort of internl/external radius will the corners have?

That's a good question and I'll ask when I ring back to pay for it. It's basically 110x60 OD with a wall thickness of 1.5mm - so it's not going to be hugely rounded corners. I was more concerned with fitting the lipo inside, which it will do regardless due to the few mm clearance it has with most packs.

[nonlineartom]

sounds pretty dam sexy. What would shipping be like on a 12s section to the UK? Would there be enough room to fit something like a parallel port for balancing?

[Glenn_M]

Jay - put me down for one length 12s
Exactly what I am after.
cheers mate,

Glenn

[adrian_sm]

A place like Eplas, will cut sheet plastic stock to size for you for a pretty reasonable price. Then you could router four corners to match internal rads. Then let people drill their own holes, but supply the correct thread forming screws to secure the end caps in place.

The controller style end plates rely on the more complex extrusion dies that have the screw holes extruded in place. This would up the ante on MOQ to pay off the die. So you would be up for probably a hundred meters to make it worth while, which will blow it out of the water most likely.

I couldn't quite visualise your glue nut in tube concept. Wouldn't the nut get in the way of removing the LiPos?

Be careful cutting it too short (i.e 1mm lengths), you will end up wasting a greater percentage of the lengths. Best would be to firm up the end plate design, and get them to cut to size and deliver. But if you have to do custom lenths, get the stock in the longest lengths that you can handle/store/cut easily.

Did you have an idea of how to mount the tube to bike? We might be able to incorporate some features in the end plates to make life easy with a bit of thought. I'll try to find some time tomorrow to doodle something up and post.

- Adrian

[Hyena]

Would there be enough room to fit something like a parallel port for balancing?

Sure would! I plan to fit a 6 pin anderson plug and 24 or 36 pin centronics plug in the end of mine
Room wise I can cut them to any length, what I posted before was more just an example.
I'll have to weigh it exactly when it arrives but I believe at this thickness it's 1.35kg/metre, so a length long enough for 12S (say 300-350mm) would be just under 500g
According to Auspost that $13 by sea mail or $22 by air

Jay - put me down for one length 12s
Exactly what I am after.

Done. Just the pipe or are you after some sort of end caps too ?

A place like Eplas, will cut sheet plastic stock to size for you for a pretty reasonable price. Then you could router four corners to match internal rads. Then let people drill their own holes, but supply the correct thread forming screws to secure the end caps in place.

SO more like a plug than an end cap - still showing the cross sectional cut through the pipe ?

The controller style end plates rely on the more complex extrusion dies that have the screw holes extruded in place. This would up the ante on MOQ to pay off the die. So you would be up for probably a hundred meters to make it worth while, which will blow it out of the water most likely.

Yeah that's in the too hard basket! Plus it makes the overall case bigger.

I couldn't quite visualise your glue nut in tube concept. Wouldn't the nut get in the way of removing the LiPos?

Yeah probably, just bash em out with a hammer in the event a pack needs replacing

Be careful cutting it too short (i.e 1mm lengths), you will end up wasting a greater percentage of the lengths. Best would be to firm up the end plate design, and get them to cut to size and deliver. But if you have to do custom lenths, get the stock in the longest lengths that you can handle/store/cut easily.

Definitely, the end cap design was just a consideration I was thinking about. The tube comes in almighty lengths (as I said over 5m) so I've got weeks to decide on the cut sizes.

Did you have an idea of how to mount the tube to bike? We might be able to incorporate some features in the end plates to make life easy with a bit of thought.

Other than a L style bracket like on controllers, not really. I normally mount my PVC ones with stainless steel hose clamps and it does a pretty good job. That said the last 2 bikes I've done don't have perfectly round tubes and one actually uses square tube which is perfect. I'm not too concerned with being able to revert a bike to standard when I do a conversion so I usually drill holes in the frame and mount brackets. An L bracket bolted to either side of a round tube makes a good platform for these to sit on, then held with a stainless hose clamp. There'd be neater ways to do it no doubt.

I'll try to find some time tomorrow to doodle something up and post.

Cool, I'm happy for any input

[adrian_sm]

Yeah plug probably describes what I had in mind.

Here is a quick sketch with no corner fillets shown, and a couple of PP45s and DB25 connectors for scale. PP45s are mounted using these.

end_cap_basic_1.png (23.98 KiB) Viewed 1213 times

Would still require some silicone to seal it up, as the eplas guys will only cut cheaply to ~0.5mm tolerence. They are usually supplying to companys that order rough sizes, and machine accurately to size themselves. But order a bunch of blocks and they would only be a couple of bucks each.

The hose clamp method is pretty effective in performance, and cost. Hard to argue there. But I would love to nut out some way to make it easy to install & remove. But I'll shut up now as thats off topic.

[Hyena]

OK your hand and software >> me and my MS paint skills
Did you already have models of those connectors on hand or draw it all from scratch ? Either way very nice

Here's another few options I was thinking of - if we were to just a flat end cap the size of the OD of the tube. Both options would be removable via screws in the side to allow removal of lipo if necessary

In pink are 2 solid blocks - sort of like the heat sink bar fets are screwed to in controllers. They could be bolted to the side of the case the end plate screwed to those.
The purple outline one is a similar idea but using L brackets - again bolted through from the side with a flush sitting end plate screwed to that.

pipe1.jpg (71.55 KiB) Viewed 1208 times

[adrian_sm]

Yep. That would work. Would also allow you to compress a flat gasket between the flat end cap and the pipe, which would be nice. Bit like the controllers.

I would probably put the block/brackets on the long side so you can get the screws more central to minimise the bow when reacting seal forces.

The connectors model were off the net, one of the beauties of using Google Sketchup is the "3D Warehouse" where people upload models, that you can then search, download and use. Very handy.

P.S. Is that the actual pipes in the image ???

[chroot]

Look like heavy aluminum box. I'll stick with ultra light weight fiberglass battery case.

[Hyena]

Is that the actual pipes in the image ???

Hell no, I suspect they're used to build bridges or similar
I just googled for an image of rectangular pipe to cut down on blowing everyone away with my awesome MS paint skills

Look like heavy aluminum box. I'll stick with ultra light weight fiberglass battery case.

As above that picture was just for illustration, the actual weight is around 135g per 10cm. Heavy-ish I suppose but in the grand scheme of things a few hungred grams on the overall weight of a bike with a 6+ kg hub motor on it isn't much for protecting your lipo investment. And your gonads
Yeah FG is nice but there's a huge amount of work involved and it wouldn't survive a big knock that these would

So, planning a little in advance, what sort of lengths would people rather I have them cut to for 12S and 18S applications ?
Do you care if it's an inch longer than it needs to be to allow flexibility for those who want to do different end cap designs ?

[teklektik]

With a little jigging, it's easy to cut ABS, Delrin, PVC, MDF, etc with a dremel router so you get a solid plug with a shoulder that will slip inside to be fastened from the side as above. Or fasten together two pieces of plastic to achieve the shoulder. You can also use a couple spring latches or straight loop latches (no spring) to hold the plug in place, making access super easy.

[Glenn_M]

Jay,
End caps not needed, I'm planning to machine some from ABS. A bit extra space (1" or so) for plugs would be nice.

Glenn

[Hyena]

I'm planning to machine some from ABS.

Have you got the gear to do it yourself or know someone ?
Care to share with the class ?

[Glenn_M]

I'm planning to machine some from ABS.

Have you got the gear to do it yourself or know someone ?
Care to share with the class ?

No - I haven't got the gear to do it but I do have some gear (router, mini lathe, drill press, files, sanders & beer). Always willing to have a crack anyway

Plan would be:

Find some ABS or Delrin or other suitable
Machine to size / corner radius to fit inside the tube
Leave a small rebate on the edge to stop the plug slipping into the tube. Maybe could use a rubber gasket here for weather proofing.
Machine holes for cables/connectors
Drill and tap holes in the edge for a M4 hex bolt (much like Adrian's "sketch" but with a rebate

That's the current idea anyway. As always - ideas under constant revising. More than happy to share as we go. Just need to get the plastic.

Cheers,
Glenn

[teklektik]

Tapped threads in plastic are workable do not generally hold up well for repeated use - particularly for fine threads like M4. You might consider a threaded insert (if Delrin) or epoxying in a rivet nut if ABS or other plastic that will take glue.

Also - not sure if it was just for reference or not, but the Centronics connector you showed was for PCB mounting - you need solder cup pins. Something like this: Centronics connectors - the female comes with a shrould but can be panel mounted (you generally don't need the standard retaining bails on the ends...).

[adrian_sm]

Count me out Jay. Sorry, I just couldn't get a design in my mind that suited my needs.

But for the record I would be happy with screwing directly into the plastic plug if done right. It is not something I would be opening everyday, only if something goes wrong. I would also try to avoid tapping the screw holes if possible, too time consuming. Come to think of it, I would be tempted to not mount the discharge connectors on the end cap either, rather just have a sort cable. Much easier to seal on the wires. Still need to cut a slot for the balance connector, but it shouldn't be too bad to seal up.

- Adrian

[Hyena]

No - I haven't got the gear to do it but I do have some gear (router, mini lathe, drill press, files, sanders & beer). Always willing to have a crack anyway

haha no worries, sounds like a good setup for your own projects but not enough to bother making stuff for others. I know a place where I could get perfect CNC plugs made but they'd probably end up costing just a much as the length of pipe itself. If there's sufficient interest I'll look into it but it sounds like there's not

Tapped threads in plastic are workable do not generally hold up well for repeated use - particularly for fine threads like M4.

There's no need to repeatedly open the case, likewise there's no need for latches. Once the packs are in there the only time I can see you'd need to open them is in the event of failure.

Also - not sure if it was just for reference or not, but the Centronics connector you showed was for PCB mounting - you need solder cup pins.

Yeah it was just for reference - I like them as they're easier to connect and disconnect in terms force and there's slightly less chance of shorting the pins than with DB plugs.
With a 36 pin connector you can also parallel the main -ve and +ve leads from each pack to a few pins to potentially charge at up to 15 amps through that connector.

Count me out Jay. Sorry, I just couldn't get a design in my mind that suited my needs.

No dramas, as I said I was planning to buy a bit anyway so if people come along later and want some I should still have a bit available.

Come to think of it, I would be tempted to not mount the discharge connectors on the end cap either, rather just have a sort cable. Much easier to seal on the wires.

Yeah true, though andersons could probably be made fairly waterproof if you filled up the back and surrounds of them with silicon or epoxy or something. That said the most basic deflector/shield would be suitable for light wet weather applications.

[voicecoils]

Just had 10 lipo packs fly off my bike and drag along the ground. Only 5 cells out of 50 in 3 packs torn open but still...

I think these aluminum boxes are a good idea

[Hyena]

Ouch!
What was the aftermath like ? any flames/smoke ?
I imagine carrying the pack home would have been a fun experience
A: Because you had to do it slowly under pedal power and
B: You'd be worried what they might do for the rest of your trip home! (in a backpack ? on a rear rack behind you where you couldn't see? strapped between your legs ? )

[RallySTX]

Ouch is right, what a heart stopper that would be. Count me in for this deal. You're talking about aluminum tubes that hold two 6S packs, side by side right? You also mean these tubes can come long enough to hold multiples of pairs right? I'm gonna need 13 of them. I will be stagger stacking first 6 then 4 then 3 for different setups. All single pack length tubes, prefferably with ends that have andersons. Gotta get at least ten so I can do one bike, and use parts of that pack to run the other bike. I have some cash now, but will most likely need to wait til April for the rest.
Brian L.

[teklektik]

I like them as they're easier to connect and disconnect in terms force and there's slightly less chance of shorting the pins than with DB plugs.
With a 36 pin connector you can also parallel the main -ve and +ve leads from each pack to a few pins to potentially charge at up to 15 amps through that connector.

Yes, I use them myself - the pins are rated at 5A and are available for inspection/cleaning on both the male and female parts. Also - the DB connectors actually rely on floating pins which frequently get kind of rigid when attaching semi-heavy gauge wiring. This can make them difficult to seat properly and fail prematurely.

[Hyena]

You're talking about aluminum tubes that hold two 6S packs, side by side right? You also mean these tubes can come long enough to hold multiples of pairs right?

Yep 6S packs, 2 wide x how ever long I cut the tube. So 12S2P in the shorter length or 18S2p/12S3P in the longer length I proposed. But as I said I'm getting it in big lengths so can cut to what ever size people want.

I'm gonna need 13 of them.

13 ? really ?? Damn man, what the hell are you building ?

All single pack length tubes, prefferably with ends that have andersons.

At this stage I'm just ordering the tube itself as it's the hard part to get hold of in the right size. Working out the end caps will come later and will likely be a DIY affair if you want cut outs for andersons.

Gotta get at least ten

I'm happy to send it across to you but it'll cost a fortune in postage - like $85 by air or $60 by sea...

[RallySTX]

I knew the shipping would be high, but if that's the price of helping out a member, and getting something I need, so be it. What I gotta do is buy a bunch of your short ones, and stack them six high, and four high, to complete the Spoiler battery box. Then I can take the four piece stack and use it on thr Stripper for daily rides. But we're talking about tubes cut to hold four batteries, or six batteries, as I just discovered. So that means I will only need five, and I will have to cut them in half myself right? End plates would be nice. That means, $100 for tubes, $100 for end plates, and about $80 to ship? If you are willing to cut them to order then mine should be cut to hold just two batteries, side by side or 12S, So each tube would be 57mm x 107mm x 160mm. so I can stack them like this.

Brian L.