Thoughts on my PCB holder for 18650

Hey Guys,

I was wondering if you could give me some feedback on my PCB and whether you think it will work well. I wanted to use the LiOn holders I bought on amazon so i could hot swap batteries if they fail. I wanted to make it modular so that the overall battery cell could flex across the PCB array.

https://www.amazon.com/gp/product/B071K5FCM1/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

the PCB is meant two hold 2x 4pack batteries to create a 4P cell, which then feeds to the adjacent one. SO in a sense is 2S4P per PCB, then i’d use 12AWG wire to interconnect 5 PCB’s to create a 10S4P pack. I put a connector for the BMS, two per PCB.

Hopefully my explanation made sense. Thoughts?

1 Like

I don’t think those battery holders will be able to deliver the full amperage that the batteries are capable. Do you know the max amp rating for those holder?

Save space and elminiate the inteconnection terminals and the balance terminals. Have one side of the PCB be positive and the other side be negative and use the opposite side of the PCB for the series connection.

And skip the battery holders.

So basically scrap the idea… :frowning:

Whats wrong with the battery holders? I’ve seen them used in other battery pack builds and it doesnt seem like there were issues with them

If you’re going to go the PCB route they’re superfluous. Just use hotglue to secure the cells and fishpaper to insulate.

Think about this layout:

No through-holes to solder, and you can achieve a higher cell density. just make your connections on the exposed bus.

Check this out: https://www.electric-skateboard.builders/t/no-words-just-pictures-delete-words-use-pm/2992/3036

Same idea, just a single P-group.

I see… I dont want to get a spot welder though… I thought my route would be easier and only requires the tools I have

Gotcha.

Honestly, I wouldn’t try this approach. It’s going to cost you a good amount of time and money to try and get a usable pack that may or may not work and may or may not be reliable. It sucks, but bite the bullet and get a spot welder.

You can also use the backside copper layer for current handling. What I usually do with high current traces is to remove the solder mask on top and add solder manually. That way you can get much more power from a trace than the copper is rated for.

hmm thats an interesting idea, im not sure how to remove the solder mask on the traces… Have you done something similar to what I’m doing?

The terminals on those holder are probably made of misture of steel to maintain springiness. Steel is a poor electric conductor and heats up. So if you have 18650 cells capable of delivering 15 amp continuously you need to have good conductivity of else you will bottle neck you batteries. Thats why people use nickel or copper to build batteries, allowing a complete battery pack to deliver 60 amp and more.

However, from what i know, there are two main attempts to build 18650 pressure battery holders:

These kits are made of copper connections and allow for high amp conductivity. However, add size and cost.

I’ve seen those options you linked, i read that the pressure holders over time can come loose if there’s too much jarring happening… seems like everything has a trade off.

I guess i can try it out and see how it works, the one good thign about this is that I can take the batteries out and try a different approach

1 Like

NESE is well tested for vibration

http://18650.lt/index.php/2017/05/01/vibrotion-test-results-of-compression-pad/

He’s on the forum if you have questions.

1 Like

I wonder if using these systems and adding a shrink wrap over it would help with the issue, but then you could potentially get a loose nut rattling around within the wrap once it come loose

Depends on what design software you are using. Usually you have to draw the same trace on the f.stop/b.stop layer. I used it for a connector board of a 2000W supply before.

Wanted to post an update since I got my boards back and soldered two “packs” together. I tested the voltage across both connected packs and make sure it came out to 13.68v (4*3.42v). Sure enough, it’s all good.

I like your 2S pcb design, great idea! I’ll probably do something similar pcb wise when the time comes :wink: