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ealex / eta3000_module

2S balancer module based on the ETA3000 inductive balancer IC
Apache License 2.0
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Hello #1

Open jharvey opened 2 years ago

jharvey commented 2 years ago

@ealex It appears we have common interests. I'm currently working on a MPPT solar panel / BMS / pure sine wave generator. My goal is to have a solar panel which I can move from location to location and plug in devices like a refrigerator. I found you as I'm starting to look into the BMS component of it now.

If you're interested my project is found here. It's a work in progress. https://github.com/jharvey/Solar_Kit

It sounds like you are having some ETA3000 boards assembled, I couldn't find the chip at JLCPCB. Are you assembling or did you get an assembler like JLCPCB to assemble it for you?

ealex commented 2 years ago

@jharvey Hello. I found the chips on Aliexpress and I don't know if they're counterfeits or original. I plan to assemble them myself - the PCB is very simple (just hot-plate re-flow) I'll have everything in 1 or 2 weeks and I'll update the README with some basic tests My plan was to have some "basic building blocks" that I can easily use to handle larger packs. 1 board for a 2S, 2 boards for a 3S pack, etc. - just glue them on some support

For the BMS you can also check https://github.com/ealex/protection_BQ7790522PWR I've build several boards an I'm already using it in some small power packs. Also, I could get that part from Mouser ...

You've got an interesting project - I plan to use these in a stationary pack - trickle charge them from a small panel and periodically power a low voltage pump to keep a reservoir topped up. Right now I plan to use some Aliexpress MPPT modules, but might be an idea to brew my own, once I get some micros that are still easily available

Try to keep the safety part in mind, from the very beginning:

Also, try to be gentle with the cells - reduce the charge current when the pack heats up, stop the charge when it's too hot, do not charge when it's too cold, etc.

One thing that I've seen: packs made from good quality cells tend to stay in balance for a long time, even when abused. I've managed to trigger the thermal protection inside a cell from a 4S pack (i did not know it had that feature, but I was lucky - it could have burned my car) and the cell dropped to ~1V when I managed to get to it and get everything to a safe state. (basically the welded tab on the positive rubbed trough the plastic insulator and was touching the outer case - 21700 cells) I've recharged the cell on a tester and it's like new - no capacity loss / no extra leakage.

jharvey commented 2 years ago

@ealex In my case I'm planning on lead acid. I can re-capture the lead and melt it down into new plates. I should be able to get a long life out of the materials. I also need fairly small amps compared to what a typical battery can produce. So I'll likely try relatively small lead plates, with a larger bucket of acid, then pump the acid with a peristaltic pump. I'm looking for a 48V pack, and I'll probably use the BMS to balance the individual cells. I may also be looking for the BMS to increase or decrease the pump rate of the acid. I'm likely doing something that is a bit odd. For a smaller incremental step. I may use off the shelf deep cycle batteries.

Good to hear you got your parts from Aliexpress. Good luck with the project.