Capacity test of every individual cell block in a bad ebike battery
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- Опубліковано 4 лип 2021
- Previous video on this pack: • A plague of big crappy...
We previously had a look at how bad this battery was as a pack, in this video I've taken it apart to see how bad things really are.
Throw money at me: / ffcossag
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Time to strip them down to individual cells...
Sooner you than me.
i bet the bms had a hard time keeping it all together lol
i once taken apart a ebike battery with 12s6p with no circuitry at all. no balancer, cheap cells. the only things between the cells and the socket was a 30A fuse to the output , a 5A fuse aswell as a PTC inline to limit the charging current on the charging port. it did belong to some cheapo discounter ebike, literally a bomb.
Theory only, but my idea is that they're re-used cells, extracted from various-state laptop battery packs or the like, stripped of their original heatshrink wrappers and re-wrapped to look new, then slapped together into a pack and sold with an eBike that has a warranty lasting as long as a politician's promises, so when the pack dies, there's no recourse and replacements (which may or may not be in the same crap category) are expensive to buy...
twocvbloke, i must dissagree with you for no reason at all lol :-D
They are indeed a mix of semi spent poo, what a stink :-D
Could be, but china has its share of manufacturers that just produce brand new trash cells. There are factories making 0.4Ah 18650s, with barely any materials inside, some make 2Ah cells that kinda work, but dont last due to impure materials and bad production machinery, etc. Its a huge waste of materials, but china doesnt care.
This is an interesting hypothesis, and I actually de-wrapped a few cells to see if that was the case, and had a look at them under the microscope. Sadly, there are no signs of re-use, and all cells appear identical. No duplicate weld marks, no scratches, nothing.
@@FFcossag Well, in that case, they're probably just plain old shitty cells, which as noted by someone else here is a thing they make seemingly intentionally...
@@FFcossag do they weigh any different?
I suspect intentionally made from rejected batteries bought from back of the truck on the way to "recycling".
Possible!
It is hard to believe such variety! Unless the QC at the factory is so bad, which is hard to believe, they must be lacking electrolyte. Maybe they were badly designed, they weren't sealed properly and the electrolyte could evaporate from them? And the ones that got the most hot had the most of it evaporated, and the lowest capacity?
I'm sure someone good at statistics could point out that you have a significant chance of having at least one or more lemons in each batch and it pulls down the average.
Can you even properly charge them if there is a bad one in parallel?
If there's a severely failed (i.e high leakage current) cell, you can't charge them very well at all. None of these are failed in that way, however.
The owner may not have used it much but did they keep it at 100% charge all the time when not using it, on the charger all the time? That probably wouldn't sit well with cheap cells.
More likely it was stored at a LOW state of charge. Cells become unbalanced, then when charging the higher voltage ones got cooked.
No, it was mostly just sitting around at some random SOC.
The BMS in this shuts off at about 4.3 V/cell, which is way too high, but I know that the customer wasn't "forcing" it. She contacted me right away as trouble began, so I don't think the battery would have had time to die that way. Though it's not impossible. These cells could be overly sensitive to overcharge.
Are they new or do they have fake caps on the ends covering up the spot welds of a used cell. If they're new they are probably Moli brand, because they are carp - secondlifestorage.com/index.php?pages/cell-database/
Too many individuals to make one battery!
What??
Ooow china made junk?
Usefull for light duty use.
The bottom end capacitys are not worth bothering with, one discharge away from the grave lol.