Inquiry about 14S40P PCB with Cell Holder and Fuse for Powerwall Project 18650

paulchen87

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Joined
Feb 16, 2024
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Dear Second Life Storage Community,

I am currently embarking on an ambitious DIY Powerwall project and am seeking some guidance from the wealth of experience within this community.

I have at my disposal 580 EVE ICR 18650 cells that I intend to utilize in constructing a 14S40P battery pack. My goal is to create a robust and safe setup, and to achieve this, I am in search of a PCB solution that caters to the following specifications:

  1. A PCB that can accommodate a 14S40P configuration.
  2. Integrated cell holders on the PCB for easy and secure placement of the 18650 cells.
  3. A fuse for each parallel group for added safety.
  4. The PCB should allow for the connection of a BMS cable to each 'S' group.
If anyone in the community has leads on where I could find such a PCB, or if you have recommendations for a custom PCB manufacturer that could assist in designing one, I would greatly appreciate your input. Additionally, any advice on the construction and safety precautions for this Powerwall would be highly valuable.

Thank you for your time and assistance. I look forward to your suggestions and being a part of this knowledgeable community.

Best regards,

Paul
 
Here's a search for Beryllium: https://secondlifestorage.com/index.php?search/511933/&q=beryllium&o=date
Along with that search is multiple articles that include similar design construction and why it's probably a bad idea

In short, if you plan on low current draw, then you may be fine over a long period. If you plan on pulling heavy current, 2A+ per cell, then you risk weakening the springs. The Beryllium springs will hold up better under these stresses.

Expensive overall. PCB of that size will not be cheap. Small PCBs that mount to a single holder might be better feasible and then mount them all onto a master plate of some sort. Interconnects will then be the issue.

Now, if this is part of a school/college/etc project for grades, then go for it. It'll be a great learning experience and you should get high marks if you include all the pros/cons of the project.
 
If you insist on the PCB route - then jag35.com has done a fair amount of practical work / youtubes to build larger batteries. You can find options on jag35.com and search "18650 PCB". Here's an example - https://jag35.com/products/18650-battery-module-board-10x - of basic stackable boards and they have support for integrating a BMSs. Youtube @jehugarcia is the creator these - many youtubes on building them - and the jag35.com website. @jehugarcia and jag35.com are legitimate offerings. :)

In my opinion, as a practical matter, you're better off spot-welding (1st) and soldering (2nd) as options. The 1st packs in my powerwall were built in 2018 and I've never touched them since - they just sit there and work. I have on occasion de-soldered a pack to disassemble the individual cells (unsolder the fuse wire) and pop the cells out - less than an hour for a 100cell pack.

The real effort is to follow good test procedure to make sure the cells are suitable for building into a pack or battery in the 1st place - and then you too should have a battery that's good for many years regardless of PCB, spot-weld, or solder.
 
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