Adding some Tesla 18650 cells to large pack?

Dala

Dala

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Feb 16, 2018
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Hi
I found an EU seller that has Tesla 18650 cells, already disassembled and selling them in bulk. Seems affordable too at 1.5/cell? Pack has 40tkm on it, so should still last a long time.

Question
How close are these in architecture, compared to regular laptop battery 18650's?
Has anyone here used them in DIY packs?
Anything special to keep in mind when handling these? They seem to come with no wrap.
 
Not sure of the specs of those... but be a bit carefull if the seller is not giving more info.
sounds a bit strange to sell them already disassembled, would make more sense to sell the complete module...
Best to try to get a few, and test them... you might be dissapointed with the capacity of a single cell.
At 1.5 they must be +2200mAh becourse you can get new ones for 1.8 at nkon.nl...

https://www.nkon.nl/rechargeable/18650-size/samsung-icr18650-22p.html
 
They are over 3000mAh, not sure about the exact specs. 3200mAh or 3400mAh maybe, might also depend on what era they come from and if they are early ones made by Panasonic or newer ones made by Tesla. If they come straight from a Tesla module then they won't be wrapped indeed. I hope the seller realizes this and keeps them separated, otherwise they will short on each other :)

Their chemistry is a hybrid NCA with nickel, cobalt and aluminium, LiNiCoAlO2, maybe in Teslas specific own flavour. But all in all they are normal 18650s, comparable to others. NCA cells aren't exclusive to Tesla either, the chemistry is used in other 18650s as well.
 
I believe the Tesla cells have no protection built into the cell at all unlike most other 18650's sono PTC or CID. I saw a teardown on youtube somewhere butcant remember the source. Will try to find it
 
Agreed with Mike, Tesla's packs have a water cooled jacket surrounding all cells, avery sophisticated BMS and a proprietary foam mixture that disperses on the cells when a problem is detected. Its not practical for any DIY project to go to those lengths so if you do go that route at least keepthe cellsif a fire/explosion retardant box :s

Edit: Upon some further research, I'm not sure if they do actually use foam as a protection mechanism but that's neither here nor there ;)
 
The chemistry isn't as volatile as LiCoO, for example. And fuse wires protect against the unlikely catastrophal failure of a cell.
 
Just thinking and observing: Why would pressure build up in the cell? Overcharge? OverDischarge? OverCurrent? Too Hot? ??????

I mention this because if you can eliminate the reasons why a cell would go high pressure, you can not worry about that type of protective measure.

So, if it's overcharge, the bms helps a lot in keeping this from happening. As well as overdischarge and overcurrent. If it's a temperature thing, then the bms can also help with this regard if it monitors that many temp locations. And if you are in an area that gets really hot outside, then take measures to keep the cells cool either actively, or don't have them subject to outside air temps.
 
tesla cell will probably be as safe (or dangerous) as any other 18650, they use them in theirown powerwalls. The reason from my understanding for all the safety features on the tesla battery modules is "risk of high speed" collision, something that will never be encountered in a home powerwall.

Pressure building up inside will vent, I see that many times on powertool batteries. Myself I would have no problem using tesla cells, I would treat them like any other 18650, maybe put a wrapper on them for safety reasons and you would be good to go.
 
Thanks for the input guys, I will take some considering before ordering 200pcs of tesla cells, considering new Samsungs are available at 1.8/pcs (only when ordering 600pcs though)
 
Dala said:
Thanks for the input guys, I will take some considering before ordering 200pcs of tesla cells, considering new Samsungs are available at 1.8/pcs (only when ordering 600pcs though)
Click to expand...

Might be worth trying to organize a group buy. Split among 3 people that's 200 cells each. No PTC/CID would put me right off, even if they were very cheap.
 
thanar said:
Why wouldn't Tesla cells be equipped with a CID?
Click to expand...

I would imagine its cheaper to manufacture in bulk, the external protection systems are top quality and also the chemistry they developedistailored for its use case. No need forCID's when tesla uses them, us, different story
 
Geek said:
Dala said:
Thanks for the input guys, I will take some considering before ordering 200pcs of tesla cells, considering new Samsungs are available at 1.8/pcs (only when ordering 600pcs though)
Click to expand...

Might be worth trying to organize a group buy. Split among 3 people that's 200 cells each. No PTC/CID would put me right off, even if they were very cheap.
Click to expand...

Why do You not check this?

[SELLING]EBAY STORE, cheap tested 18650 cells

[size=medium]https://www.ebay.nl/str/grooter[/size]

I bought 200 and they are all in prime condition.

F. eks. Samsung ICR18650-26Hat 1.20 EUR/ea. They are all above 90% of new capacity, and they have CID built in ;)

ChrisD
 
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