Ali Express my man!

Hi Simon, I used two Meanwell Power supplies. From Memory, one is a 5v 55a version for the TP charging modules. (Overkill!) and the other was 12v 25a for the Opus Chargers. Again, probably do not need that much, but I had them laying about.

power2spare.net

batteryclearinghouse.com

batteryhookup.com

jag35.com

Hi Elvezio, I approached IT recyclers to get most of my batteries. It took a while to find them. Also join a few facebook groups. Look up ‘DIY Powerwall’ on Facebook and see what you can find. Good luck!

Hey AK, I let the cells sit for weeks before retesting them. Generally, I aim for at least a month of resting before checking voltage again. After that, I did not put anything in my wall that had fallen below 4.14. After testing a few thousand I did notice that some brands of batteries just do not like sitting up around that 4.20 mark for long. Plus I don’t really trust the opus chargers to put them up to 4.20 properly. 4.10 – 4.15 seems reasonable to me to keep.

thank you very much for your great article and your great work.

You write about “self dischargers”: What is the critical voltage where you decide if you have a self discharger or not? Do you let the cells rest for a few hours after charging to 4.20V and do a first measurement which you compare with the result of the measurement after a week?

BR,
AK

Thank you very much.

Hi Antonio, you could try a few places. Start with any IT recyclers, after this you could try to approach some IT repair companies. Usually, they only have small volumes though. After that, you can purchase new ones. Also, check out the many 18650 Facebook groups. Usually, they have a few going. Good luck!