FlexiPack, no soldering, no welding, battery pack building method. Looking for participants for testing phase.

DIY Builds Battery Builds
,
#1

Hey,

I’ve been developing another battery related product alongside my BMSs (for synergy), which is an easier method for building battery packs, especially for people without spot welding equipment. It’s quite beginner friendly.

I have a couple of prototypes built for my own development and testing. I initially started with 3D-printed parts, but I have now transitioned to actually custom ordering parts directly from China via alibaba and have gotten the parts and I’m interested in scaling up the testing to a few interested participants here in the forums.

Mechanically the system is similiar to the trampa/vedder battery pack structure, but not identical. I came up with the mechanical concept for my own design with a colleague at the office before I had even checked the trampa’s version (picture below of it).
image

My pack design uses honeycomb cell packing with minimal wasted space in-between cells, so it allows for high degree of packing efficiency. It’s also a lot more simple, as it only consists of 2 different main mechanical pieces.

At this point I want to keep the design still non-public, as it’s still a WIP. So I want to get a few interested people and run a private group thread in the PMs on the forum for the duration of the testing and then either run more development on the design or if it seems ready for publishing, then publish the results on this thread.

So preferrably, people with battery pack building experience (or at least know the proper use and safety around loose lithium cells) that want to build a new pack with 21700 cells (ie. Samsung 21700-50E. ), because that’s the cell mechanic that I developed the first prototypes for, so that’s what I have the first round of hardware ordered from the China for.

I will make custom pack designs for the participants based on what they want and will require payment for the parts and shipping, I’m not asking for profit at this point. You will need to source your own 21700 cells though, I will not be shipping any. Depending on the wanted pack design, I’m estimating a cost of 15€ for a 12S1P or 25€ for 12S3P + shipping (20-30€ via DHL), just to give some idea of want kind of price range this initial testing will be for. Payments will need to be done via a bank transfer and an invoice that I will write for the parts and shipping.

Are you interested in participating? If so, below is a generalized poll about your experience in building battery packs, the answers are public.

Battery pack building skill
  • Professional battery builder, I build and sell packs for people
  • Hobbyist battery builder, I have built multiple packs for my own use
  • Beginner battery builder, I have built 1-2 packs for my own use

0 voters

If there are other questions or inquiries then feel free to reply and start a discussion.

6 Likes
#2

Depending on the layout I’d like to build a 12S3P battery, how flat can the packs be?

#3

Are you talking in the cell length or width direction? In cell length direction it’s 76mm and then on the width direction, depending on which orientation you measure it, either the cell is the thickest part or there is about +3mm extra mechanical distance.

Can you provide a sketch of your planned layout, so I can give a more detailed mechanical dimensions?

2 Likes
#4

I’d be interested in looking at this, but are you only doing 12s?

3 Likes
#5

I’m doing any cell configuration you want. Even to higher S-series than 12S.

1 Like
#6

I’m interested in testing! Novel battery building solutions really interest me. I have a mountainboard I can easily swap batteries in, and I need a few spare 12s4p batteries for extending the range on my other boards.

The mountainboard is a great high-vibration environment for testing. For example, NESE cell holders failed on this setup:

#7

Hmm I’m interested then. There were some major problems with the Trampa one though, especially centered around not having enough pressure on the cells.

Arcing occurred, similar to the NESE problems, and some of the fiberglass pcb material has been shown to break. Not to mention the battery fire that we saw years ago

Are you aware of all of this? I have not seen your method yet of course, just putting this all out there

1 Like
#8

I would be very interested in designing a test pack for you to test. I checked your thread for the damage with the NESE design and I would be very interested to see if my design would survive the use.

My design uses the pcb as one of it’s main mechanical parts, so I’m very curious to see if it holds up. Do you have any more specific information how the PCB broke in the trampa’s design?

1 Like
#9

I’m fairly certain it was posted on this forum but I can’t say where, sorry. If I find it I’ll put it in here

2 Likes
#10

Extremely interested in testing. I’ve had many issues welding my own packs, but I have a ton of cells on hand to use.

The main issue I have is vibration and shock. Welds can come loose with the abuse I put my esk8s through.

Let me know. Very very interested.

#11

Welds shouldn’t be holding much load to begin with in a well designed battery pack, but I digress

8 Likes
#12

Yeah I know a lot of things shouldn’t happen, but in my experience anything that can go wrong, absolutely will go wrong.

2 Likes
#13

I have had my 5+ years old 10S6P with samsung 35E cells built into a pelican style case hold without problem with 12000km+ ridden with it. Most important part has been isolating/damping the pack from the walls of the case via foam padding.

IMG_20230214_194610
IMG_20230214_1946101600×914 447 KB

IMG_20230214_194641
IMG_20230214_1946411600×737 241 KB

1 Like
#14

I’m speaking more of underslung flat packs where my issues have been evident.

I’ve only just welded a brick pack and haven’t rode with it yet, so I’ll soon know the results of that.

Is your system only for brick packs in topmounted cases or will there be a version for underslung flat packs?

1 Like
#15

It can also be used for underslung flat packs.

1 Like
#16

I’d be interested in a 10s pack, no battery building experience though, have done my research for building my own but never got around to sourcing materials etc

2 Likes
#17

This just became very intriguing. How much space does it take up in a flat pack configuration? Like how much additional space would I need in terms of thickness, length, and width?

2 Likes
#18

Here’s an illustration of the spacing. 12 cells in a row (electrical connections not shown in this case), my design on top, optimal packing on the bottom.

Regular welded pack (cells touching each other) optimal total length with 21700 is 21mm*12 = 252mm, width 21mm.
In my design the cell spacing is 22mm, cell diameter + 1mm, so with 21700 → 21mm + 1mm = 22mm. With 18650 it would be 19mm and this goes for the whole honeycomb pattern. Width of the cell is the outmost dimension. The mechanical structure adds 2,55mm to both ends.

image
image1491×565 7.43 KB

EDIT: my design also has the added benefit that the cells can’t mechanical and electrically come into contact with each other, unless the pack mechanically fails.

EDIT2: In the cells length direction it’s about 76mm in total with the mechanical structure.

3 Likes
#19

@rusins
How big were those NESE modules in the cell’s length direction? I’m just wondering how much space you have in the pelican style case that you used with the NESE-modules?

image
image1411×821 113 KB

1 Like
#20

Each 1s6p Nese module dimensions are: 140.7 × 80 × 23.5 mm
My box’s INTERNAL dimensions are 235mm x 170mm x 95mm.

My 11+1s 7p battery brick really had to get squeezed in to fit. Shouldn’t be an issue with any 12s4p battery I think, as long as the parallel rows are staggered in a hex-shape.