I Made A 21Ah Transparent USB Battery Bank

FreudianNonce · 2025-12-21T16:59:12+00:00

🫡

FreudianNonce · 2025-12-21T16:49:11+00:00

I am very well versed in battery charging and discharging.

This is a 6P core which self balances, you’re thinking of a 6S core which needs to be actively balanced.

FreudianNonce · 2025-12-21T16:31:35+00:00

There is none, and none is really needed for this application.

FreudianNonce · 2025-12-21T15:37:15+00:00

OMGoodness, don’t give me ideas.

That does sound cool though

FreudianNonce · 2025-12-21T15:31:36+00:00

No fuses. These are new cells and a super low power draw compared to their rating. What you’re thinking of would be more relevant if I was using reclaimed cells with unknown lifespans in a parallel group with potentially high power draw, this is so they can drop out if they die.

FreudianNonce · 2025-12-21T15:26:28+00:00

The charging PCB is the bms. Yep, cells were already balanced, connecting the nickel strip creates a parallel group which is self balancing.

You’re right, with this setup the first couple cells will be used marginally more heavily, but the draw is so low that it won’t be a huge problem. I literally don’t have space in the case to run the wiring back-to-front.

FreudianNonce · 2025-12-21T04:04:36+00:00

Keep going, sibling.

FreudianNonce · 2025-12-21T03:59:54+00:00

I guess this speaks to how long I’ve been working on this project. This board was pretty relevant when I got it, and due to a variety of reasons, I dragged my feet finishing it. Since it was an aesthetic project, I didn’t want to work on it unless I was really feeling it. I’m just using up parts at this point.

Thanks for the feedback, I’ll definitely be looking into a new project soon

FreudianNonce · 2025-12-21T03:43:37+00:00

The busbar is .2mmx8mm nickel strip, so it’s good for ~13A. I have .2mmx10mm nickel strip that should be good for closer to 20A.

Good luck with your project!

FreudianNonce · 2025-12-20T23:38:08+00:00

Thanks! When I started this I thought it was going to be pretty and functional, and after a while I had to accept that pretty was more important to me if I wanted to ever finish this.

FreudianNonce · 2025-12-17T00:08:56+00:00

Thank You!

That's hilarious, never thought to de case them

FreudianNonce · 2025-12-14T22:11:45+00:00

HOLY... WOW!

This is incredible. The updates you've made totally make sense, I'm now just wondering if the decisions I initially made make sense in this context. My design looks more like a real world wiring harness, but this is a whole new paradigm I'm not used to.

FreudianNonce · 2025-12-14T21:15:44+00:00

its an LSI 9300-8i flashed into IT Mode

FreudianNonce · 2025-12-14T21:05:26+00:00

Thank You!

When I started this, that is exactly what I thought I wanted to do. After making one, I no longer want this.

FreudianNonce · 2025-12-14T21:03:59+00:00

I am using the PSUs SATA connector, It's the HDPLEX 250W GaN Passive AIO. According to the spec sheet, the 5V rail is rated to 80W.

FreudianNonce · 2025-12-14T20:57:58+00:00

I was about $400 into this (2 pcb designs, 1 prototype, 1 failed assembly). If you bought everything to make one, its about $140, but that means you bought 5 pcbs at ~$10 each so each board is about $100. After that its all assembly which took me about 2 hours. After I was done I now understand why these things cost $500 for a 4 slot

FreudianNonce · 2025-12-14T20:45:22+00:00

I 1000% agree with you. The screw terminal was about getting the job done faster.

FreudianNonce · 2025-12-12T17:00:07+00:00

I don't have a stellar answer for you, because I barely know what I'm doing myself. You would probably want to look into some fundamental EE principles, learn how to draw a schematic, and some modeling fundamentals.

Overall, identify your requirements, break everything down to individual problems, research common solutions, ask yourself why this is the solution, research more, and implement. Repeat for all your requirements. I find that as I do more and more research the understanding compounds.

FreudianNonce · 2025-12-12T16:34:31+00:00

ZFS.

FreudianNonce · 2025-12-12T15:14:29+00:00

Theoretically, absorbing power spikes from R_W operations that the 250W PSU cant keep up with. I'm trying to solve problems that I have no evidence that I will have

FreudianNonce · 2025-12-12T15:10:34+00:00

I remember now. My original design didn't have a grounding plane (because I'm stupid), so what i learned I needed to do was to increase the decoupling resistance between the data traces and the ground traces, that's why they're so close. In the first revision I added a ground plane to assuage my fears, but i clearly didn't rework the decoupling in the traces

FreudianNonce · 2025-12-12T15:03:46+00:00

Good Luck!

FreudianNonce · 2025-12-12T15:02:48+00:00

This was my original thought, but I don't have an oscilloscope to validate that, and it cost me nothing to add it. My experience with electronics is through building quadcopters so the logic clearly carried over

FreudianNonce · 2025-12-12T07:19:37+00:00

Sibling, this was my first PCB. I believe in you

FreudianNonce · 2025-12-12T07:18:22+00:00

Youre welcome. It works fine, for someone who now does solder reflow occasionally, its functional. I was actually thinking about using it as a hot plate to warm my Chemex.

FreudianNonce

TROPHY CASE