question about rentability

Hello guys, i have an opportunity to buy 970x usedcells from a range 1200-1399mah for about 250 Euros

Do you think it can worth to build a system with that ? after all , it is about 4.4kwh ?

In my opinion it worth it, but i prefer to ask experienced builder

That's about $0.80/cell. A little low on the capacities, but a decent price. The big question is, what was the original capacity of those cells? If there were 3000+mAh, then I'd be leery.

If this is to help get your feet wet and get building, then it'd be a good deal as you can build a full 14s string.

I would be more concerned with the original capacity spec and the amount of capacity loss / degradation they have. You may be looking at cells that are close to their end of life.

Even for most used batteries I am finding, most of the old, end of life, or near unusable ones are coming in around that capacity. The cost per cell is also higher than I would want to pay for that capacity.

Personally anything under 2000mah (2250 or higher preferred) I dont even consider building with because density makes a huge different in the overall cost to build. Using any system (cell holder, spot welding, PCB) 1500 vs 3000 mah doubles all your consumable costs, and you have a project physically twice the size for the same capacity.

Crimp Daddy said:

Using any system (cell holder, spot welding, PCB) 1500 vs 3000 mah doubles all your consumable costs, and you have a project physically twice the size for the same capacity.

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I can see that. This would effectively be calculating about $1.60/cell for a 3000mAh variant. It's still a little cheap, but as you mentioned, you need twice as many cells, and need twice as much wire to connect them (not to mention holder if going that route).

2x wire to connect
2x time to solder/spot weld connections
2x the solder/nickle-strips
2x the size of bank/space

However, that's about all the further it goes. All the other equipment is the same regardless. So just need to weigh in if it's really worth "your", or in this case vivi0512's, time worth it. That's the ultimate question here for this type of purchase.

Another thing to consider, if these are 100% working condition (no duds or self draining cells), then it's an overall decent haul. Just don't expect to be running and heavy loads from them, that's all (like oven, air con, electric water heater, etc)

Thanks for your answers but it is 0.25euros / cell

How do you get 0.80euros / cell ( or dollars because euro and dollars are close )

So 28 cents USD per cell... for 1200-1400 mah (cell of unknown condition, health, or remaining life ?) I assume they have been processed by someone and thats their sell pile?

Just for comparison, what I get works out to about 12 cents USD for cells, and most of the time they end up being very healthy 2800-2900 mah cells from medical packs. Twice the capacity for half the price.

That said, even if you are comfortable with the price, which is fine (I've paid more for cells before when I bought model packsfrom people like Tom / BatteryHookup) its the cycle count and remaining service life. All I am saying be aware of what you might be getting into.

If you have self discharges, or they are old cells from laptop packs which have a high cycle count, then the deal might not be as good as it seems.

I know this stuff is fun or can get exciting, but I've walked into poor cells enough to become extremely picked about what I spend my money on. Not trying to turn you away from your deal, but just be aware of what ur getting and have realistic expectations. I personally have just had terrible luck with laptop packs due to high cycle life and degradation.

vivi0512 said:

Thanks for your answers but it is 0.25euros / cell

How do you get 0.80euros / cell ( or dollars because euro and dollars are close )

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Yes, correct. I'm not sure how I got the .80. I wonder if I added an extra number in the calculator w/o realizing it. Ok, 0.25/cell is a "lot" better


If you can get a list of cell identifications, then you can see what the "original" rating was. Then you can make a much better educated guess. If they were originally 2000mAh, then they probably have a lot of life left. But if they were 3000mAh, they are almost on their death bed. Just sayin....