I bought a huge box of 18650 batteries to build a power wall for our off grid homestead.
I got this box from Philip20 on YouTube at a good price. He had sorted through about 2,000 of these at one time and picked out the good ones. Later he lost interest in the project when he got his Nissan Leaf batteries to power his home with.
This box contains six super capacitors, some battery retainers, some battery packs and about three hundred 18650 batteries.
I still have to charge these up and test them all to see what their capacity is before I can start using them. Meanwhile I have to buy the supporting hardware to put together the lithium battery power wall. I will need balancing circuits and charge controllers to run these.
I figured that with 300 batteries at an average of 2,200 mAh capacity, I have about 75 battery banks at 15 volts each. This gives me about 165 Amp Hours of battery capacity for a solar power wall.
You can find Philip20 here: https://www.youtube.com/channel/UCXwk6f8UMq_zyEYIUfJs0_g