Frugal Power Wall

This guy built a power wall out of recycled 18650s.

I guess he saved some $$$s.

Anyone wanna split a kilo of 18650’s?? :cowboy_hat_face:

Recycled batteries. In order for that to make even a little sense, diagnosis needs to be performed on each and every cell to discard sufficiently damaged and/or ruined ones.

I prefer a good set of new, quality cheap cells. In order to maximize lifespan, I'd restrict charging voltage to 14/15th of maximum to dispel voltage related stresses (3.92/4.2V, for example). In such case I'd need ≈50% additional cells for the same capacity/energy, with a fourfold lifespan (or more so). Source: BU-808: How to Prolong Lithium-based Batteries @ Battery University

He actually did test them all to rule out ones which have a low initial voltage, which heat up, are below 2000mAh capacity or self discharge.

He charges to 4.11V.

Charge balancing, proper charging algorithm?
I just skimmed the article but ebay circuitry and mismatched batteries is an explosion waiting to happen.
What i would love is a per battery independent circuitry and infinitely expandable, with selectable charge and discharge points (ie set for 4.0V at fully charged) and we could buy batteries as we feel like it (or recycled) and keep expanding with no risk from over charging/discharging.

Yup uses batrium stuff for charging/balancing along with longmons on each pack.

Whats the big deal.

Just get the mother of all voltage boost circuits and run them 1S 5000P

Add more any time you like. auto balanced


whats that?

very interesting, and very expensive

An interesting home solar project for sure. Pete has a list of everything he used to build his system and much detailed info here:


When I looked at doing something not quite this large, I decided it was worth reading out the BMS information so I could avoid the trouble of tearing apart and testing cells from packs that were unlikely to produce a good yield.

My preliminary results were very promising. For about 30s effort/pack, I could identify most packs that had cells that were low-voltage and/or low capacity without ever cracking the pack. In the end though I decided that it didn’t make sense to proceed given the increasing availability of packs from totaled EVs, not to mention declining prices for large, new, commercially produced packs. Some details in my sig.

Pretty sure this was only a money saver if his time is worth nothing, but hey, if he enjoyed himself, who am I to judge?