why not vertical stacking of 18650 battery pack

[guctony]

Hi everyone,

I searched the forum but I could not find a reference. and I am a newbie so My question might be naive. Having said that I plan to build a battery pack for my ebike. But I would like to know why no one is packing batteries vertically one on top of each other like a flashlight set up then combine parallels. Is not safe to rely on batteries terminal to touch each other directly. Would it lose connectivity. it seems this way easiert this way it will reduce the amount of work.

 

[Matador]

If you stack them in series like in a flashlight, then yes the connection would most likely not be reliable for the kind of currents ebikes uses. Plus the positive side is not like in AA batteries were they have a nipple to exerce pressure on the next cells negative terminal.

 

[guctony]

thanks for the reply

 

[guctony]

what about adding nipples or magnets

https://www.ebay.com/itm/6-Flat-Top-to-Button-Top-Li-Ion-Battery-Adapters-18650-14500-18500-18350-/274368688990

https://www.fasttech.com/product/2157806-stainless-steel-flat-top-cover-cap-for-18650

 

[Matador]

Magnets or not very good electrical conductors. They have bad resistivity, add weight, and can loose their magnetic fields if overheated. Magnets are a poor solution for anything with EV range power needs.

 

[Matador]

As for "adding" or welding nipple. Best to just spotweld the cells with nickel tabs. Solderless packs looks elegant in theory, but in practice, involve a lot of engeneering overcomplications that usually lead to poor practical yields cell imbalances.

 

[Hillhater]

Try a search..
There are multiple threads on this method of pack build.

 

[john61ct]

The keys to solderless is

firmly clamping the cells to keep them fixed in place

both laterally against each other and/or the housing walls

also maintaining the pressure and low-resistance conductivity of the end connection points

in the face of extreme shock/vibration

the plastic wrap not being reliable enough to prevent shorting through the wear points.

The fact that the walls of the whole cylinder is a negative terminal is a big obstacle.

But these are not insoluble engineering problems, as the market grows effective and cheap solutions will emerge to replace the current welding standard.

We're just not there yet.

Amateurs muddling through their own solution might just help lead the way, but for us these are not trivial issues.

Material science has not yet given us a robust permanently flexible but highly conductive substance yet afaik, so a specialist spring design would be another approach.

 

[guctony]

I just Received my sony VTC6 C6 batteries they have build in nipples as they were for Vape devices. I guess I will try to design a 3D print case to individually store 15S5P battery pack linear to cancel spot welding. My problem is here in middle east it is very hard to get Lithium batteries. So I dont want to spor weld them. As every 6 month I would inspect them individually to repack them.

I will share my designs as I would need alot of advice from the pros.

 

[goatman]

what about adding nipples or magnets

https://www.ebay.com/itm/6-Flat-Top-to-Button-Top-Li-Ion-Battery-Adapters-18650-14500-18500-18350-/274368688990

https://www.fasttech.com/product/2157806-stainless-steel-flat-top-cover-cap-for-18650

ive been playing with magnets and plasti dip, using upto 10amps with temps upto 100f. its an easy solution for someone without any special tools and on a budget

https://endless-sphere.com/forums/viewtopic.php?f=14&t=106190&start=75#p1563730

 

[999zip999]

Check this out
https://endless-sphere.com/forums/viewtopic.php?f=31&t=88051

 

[guctony]

Hi I just wanted to update for my battery pack custom 3D case for stacking my 15S5P battery pack.

 

[guctony]

AND these are proof of concept prints

 

[john61ct]

I see at least three completely different fundamental ideas there.

Are those either-or, or are you imagining combining them?

 

[guctony]

I started with the 14S2P setup as to get some experience ant that wast the only practical fit size form my Frame. In the end I decided backpack case. As 14s5p vruzen box is not going to fit anywhere in my frame.

But the 2nd iteration is still on the table for down tube fixation. Geometric design are just case study of how to hide battery box in the frame.

 

[guctony]

 

[john61ct]

Personally I prefer the look of fully filling the triangle, plain flat side panels for a clean look.

If there is empty space still available at the top to hold all the controller etc electronics maybe a little roadside toolkit, so much the better.

 

[guctony]

well its going to my first battery pack and even though I buy a battery case for 14S5P from Green bike. I am not inclined to spot weld. Sony VTC6 18650 batteries. Because in middle east it is very hard to get quality lithium Ion 18650 battery. Its not allowed by air freight.So something goes wrong I will be having hard time reversing the problems. And it is also very difficult for me to design an triangular Vruzen battery back as I its my first pack design and vruzen architecture is not easy I guess to make it triangular.. I like to keep it simple and plain rectengular shape for the time being.

 

[guctony]

Hii I wanted share my finished 3D printed 14p5s Battery case project with some test run I the desert.[youtubehttps://youtu.be/NY7uRMDsB94[/youtube]

 

[R0bb1e]

Nice work!