Headway cell frames-now with pictures!

[reagle]

We just received our order of cells (direct from Victoria) at work, and she was nice enough to sell us the battery frames/assembly blocks like the ones she was showing on a picture in Headway group purchase thread.
They look like the PSI ones, but dual- each one hold two cells and interlocks with the neighbors. What I can't figure out is how to use them on the positive end of the cell. That end seems to be just a tiny bit wider than the negative one, so I have to force the blocks on it, which cracks some.. Has anyone dealt with these yet?
I know they are pretty new, so maybe they are still tweaking things, or maybe I am being silly and doing it wrong.

 

[dnmun]

is it possible the lego blocks are different sizes for different ends? canyou measure and show pictures? how much cracking and where? i don't think they thought about this in the group buy here. did you get the headway BMS too?

 

[reagle]

I thought so too, but on a second thought it would not work Or at least it will limit the polarity configurations you can get since some time you have to flip one of the cells in the pair. Single blocks like PSi's would be OK, but PSI cells are also symmetric ..
The walls are pretty thin, so once they crack, you see something like a 3mm gap at the end. I'll post pictures later today. I did also order charger and BMS for 8S configuration, but these are coming separately. Cells came packaged in pairs in small cardboard boxes, with assembly blocks and even metal squares for connecting cells. Took less than a week UPS saver from Hong Kong to upstate NY by the way.

is it possible the lego blocks are different sizes for different ends? canyou measure and show pictures? how much cracking and where? i don't think they thought about this in the group buy here. did you get the headway BMS too?

 

[dnmun]

how much did shipping cost for how many cells? you got the blue cells with the short welding tab on each end? 2/box?

 

[reagle]

We got blue S-series cells with screw ends, 2per box. 34 cells +BMS+charger shipped were about $100 for UPS saver

how much did shipping cost for how many cells? you got the blue cells with the short welding tab on each end? 2/box?

 

[dnmun]

ok, you got the pictures up.

the inside looks like it has little bumps that actually snap behind the crimp ring around the cell?

is that what interferes with the positive end? how tight is the negative end and how hard do you push to split it, like 5 lbs or 50lbs?

 

[reagle]

No, they just have a bit of a lousy mold- the inside walls look flat, with no retaining features, but a few areas have recesses (almost like a void). The negative end slides right in with barely any effort, just some friction. Positive one does not at all- I'd guess the effort is closer to 50Lbs for a non-mechanical engineering me On the picture you can see how far it goes in before encountering resistance and starting to pull the plastic apart down the crack.

What's puzzling is that on the pictures in Headway buy thread, those things are on both sides with apparently no problems. They are also yellow and not orange- but who knows how cameras see things..

ok, you got the pictures up.

the inside looks like it has little bumps that actually snap behind the crimp ring around the cell?

is that what interferes with the positive end? how tight is the negative end and how hard do you push to split it, like 5 lbs or 50lbs?

 

[boostjuice]

gotta love the attention to detail of chinese engineering....

 

[reagle]

Or customer support- still waiting for answer from Victoria
I do realize she is a sole point of contact for all of us, and some orders are much bigger than other, but that's when you create sales department
She did not know why they would not fit and was going to find out.That was probably a couple weeks ago. I proceeded anyways and put a pack together, ignoring cracking plastics and all.
Is anybody else still waiting for chargers/BMS ordered from Headway direct? We got the cells, but everything else is delayed for some reason.

gotta love the attention to detail of chinese engineering....

 

[HAL9000v2.0]

I am waiting for chargers and bms for 3 weeks now the cells arrived nicely in a week. She did not responded to my last 3 mails asking where is the bms. Today I send that I don't need it any more.

She was no problem to deal with until now and I do not know what happened so I will wait some time to write my opinion.

 

[reagle]

Same here- it's all prepaid, so I kinda still want to get what we paid for, not to mention I have no BMS on hand to use cells without a risk of damaging them.
There are large group buys going on, so she is probably occupied with them. Not much we can do, but wait (and post here

 

[HAL9000v2.0]

Yes, but to write down "wait another week" and hit send takes 5 seconds.

 

[Lapwing]

Injection molded plastic shrinks as it cools. Every plastic part is designed to take this into account. Different resins and plastics, different amounts/thicknesses, even a color change will matter. Others here can probably fill in the details better than I.

However, just like machined parts- critical dimensions should have a go/nogo quality check.

Obviously this was not done. My guess is it is the moulding at fault, but it could easily be the cell casing dimensions variable during production, or even the thickness of the shrink tube when shrunk. I'm thinking that a redesign of this part to accomodate the variables would not be difficult.

The Lifebatt design lego looks beter designed. did I say that?

 

[reagle]

It's either the wrong material (not flexible enough to snap back), or not taking into account the fact that their cells are not symmetric. PSI/BMI cells are cylindrical, and both ends are exactly the same. Headway cells have a flange like thing on one end and that's exactly what gets stuck. The other end fits fine

Injection molded plastic shrinks as it cools. Every plastic part is designed to take this into account. Different resins and plastics, different amounts/thicknesses, even a color change will matter. Others here can probably fill in the details better than I.

However, just like machined parts- critical dimensions should have a go/nogo quality check.

Obviously this was not done. My guess is it is the moulding at fault, but it could easily be the cell casing dimensions variable during production, or even the thickness of the shrink tube when shrunk. I'm thinking that a redesign of this part to accomodate the variables would not be difficult.

The Lifebatt design lego looks beter designed. did I say that?

 

[Ypedal]

The PSI leggo's have some slop in them, it's not a tight fit, but once you secure all the cells in the leggo's with hot glue/silicone/other and bolt panels on the sides it's a solid pack.. i'll be playing with those tonight with any luck.. pictures to come ! :wink:

 

[AndyH]

...The Lifebatt design lego looks beter designed. did I say that?

Dunno. I didn't hear it. :wink:

LiFeBatt and BMI have the molds for the 4-cell carriers they use for their HPS packs. The single-cell 'lego' block is PSIs design.

'As a dealer for PSI I can purchase the 'lego' blocks but cannot purchase the HPS pack parts.

Andy

 

[reagle]

HAL, any news there? Still waiting here and no answers from Victoria

Yes, but to write down "wait another week" and hit send takes 5 seconds.

 

[boostjuice]

The PSI leggo's have some slop in them, it's not a tight fit, but once you secure all the cells in the leggo's with hot glue/silicone/other and bolt panels on the sides it's a solid pack.. i'll be playing with those tonight with any luck.. pictures to come ! :wink:

Another way - neater in my opinion- is you can just wrap a single layer of electrical tape around each end of the cell and then they fit snuggly inside the lego blocks with no slop.
I would be very concerned about people building packs using the lego blocks and brass/copper connecting straps without one of these modifications. The 'slop' is enough for vibratory pressure to be placed on the studs leading to premature leakage failure. ie one cell moving in its block causes its neighbouring cell to also move and impact within its lego block. Using flexible braid rather than rigid strips/straps would also help minimise this problem.

Or you could custom make vibration absorbing cell retainers out of packing foam using a piece of pipe and a stanley knife....

 

[BMI]

Injection molded plastic shrinks as it cools. Every plastic part is designed to take this into account. Different resins and plastics, different amounts/thicknesses, even a color change will matter. Others here can probably fill in the details better than I.

The Lifebatt design lego looks beter designed. did I say that?

....yep, you said that!
It looks like the type of plastic Headway uses to make their frames is a very brittle, poor quality plastic (looking by the way that frame broke). The BMI cells fit into the BMI frames perfectly and hold the body of the cell just right without being too loose or too tight. I guess it is just a difference in engineering tolerances and material quality.

 

[BMI]

I am building a couple of custom e-bike packs for a regular customer of mine who needs a very reliable long lasting battery since he uses his e-bike daily to deliver advertising pamphlets. These special frames are designed to hold 8 or 16 cells. These end frames are precicion machined from acetal or nylon instead of being moulded and also have precision machined aluminium links for connecting multiple cells together in parallel. An example of one of these frames is shown here-

The whole pack will be assembled using these frames and then the pack will be completely encapsulated in heatshrink. The idea is to make a very lightweight, professional pack. All this and with not even the slightest sign of any duct tape.

 

[reagle]

Oh, I did not realize we have such an easy solution- just get PSI blocks from Andy, take up the slack with some type of a spacer and you have a nice mounting solution for Headway cells. I would definitely feel that to be a much more secure arrangement than cracked plastic and cells hanging by their screws Any issues with brass connections touching whatever metal the cells are made of in terms of galvanic pairs?

The PSI leggo's have some slop in them, it's not a tight fit, but once you secure all the cells in the leggo's with hot glue/silicone/other and bolt panels on the sides it's a solid pack.. i'll be playing with those tonight with any luck.. pictures to come ! :wink:

Another way - neater in my opinion- is you can just wrap a single layer of electrical tape around each end of the cell and then they fit snuggly inside the lego blocks with no slop.

 

[XRuss]

Hi boostjuice. Nice. Could you please expand on how you cut the percision round holes in the foam?

 

[gogo]

I think he said he used the end of a pipe to cut the holes. The method seems an even better solution than the rigid lego type holders because it allows for thermal expansion without stressing the connectors and is easy to customize. You would probably need to have an outer enclosure or separate framework, but that's easy to work into the design of a pack.

 

[boostjuice]

Hi boostjuice. Nice. Could you please expand on how you cut the percision round holes in the foam?

Materials and equipment:

1 x length of 1.5" OD pipe (38.1mm outside diameter) at least 50cm long is preferable so it is easier to keep a hold of with two hands and keep perpendicular to the foam when cutting the holes. This forms slightly undersized holes for the insertion of the 40.6mm OD PSI/BMI/Lifebatt cells which means they fit snuggly with some foam compression. This stops them wanting to slide within the holes, but the foam can still flex to accomodate vibration, impact shocks and thermal expansion which is something that plastic blocks do very minimally.

1 x right angle/barbed hook (can be made out of a coathanger or piece of wire). This is used for removing the cylinders of foam that end up inside the pipe when you press out the holes.

1 x half moon hand file - This is used to remove material from the inner side of the pipe wall, forming the bladed edge needed to slice the cylindrical holes.

1 x hacksaw or stanley knife for cutting the foam blocks. I found a hacksaw gave straighter edges and the serrated edge didnt grab the foam when cutting like i first expected.

1 x ruler and set square for marking out the foam blocks for cutting

1 x marker pen for drawing out the lines on the foam blocks

25mm > 40mm thick packing foam (available from packing material stores, specialty rubber/foam stores and sometimes even the dumpster behind your local whitegoods retailer!) I stress that you must use foam with enough density otherwise you will not be able to cut it neatly - if at all. Soft grades of foam 'fall over' and 'morph' when you try to slice and cut it. Polyethylene packing foam is ideal. Polystyrene foam crumbles and is no good.

Once the foam blocks are cut to size to fit the allocated enclosure/frame, the cell spacing is decided upon and the hole centre locations marked on the foam it is time to bore them out with the pipe. placing each foam block on top of a piece of softwood on the floor, you simply apply downward rotating force with the bladed edge of the pipe onto the foam and it cuts neat holes with minimal pressure required. To align the pipe precisely you simply look through the top of the pipe and line up the crossed lines that mark the centre of each hole location. Its just like looking through a rifle-scope, except you want to centre the crosshairs in the middle of the circle.
The piece of softwood under the foam block is used so that when the pipe cuts through the block, it has a soft surface to cut into that wont blunten the edge.
Once one block is cut, it can be used as a die template to cut the others without marking. You just place the cut block on top of the uncut block and use the preformed holes as guides for the pipe. You just have to be sure that the two blocks are set square and held securely on top of each other. I used a few bricks to make a perimeter wall around them so they didnt move around.
Neat results can be obtained with patience.

 

[XRuss]

A really neat way to go. I'm in with my new HW's from May buy. Thanks juicer for the detailed instructions. CHEERS