so simple answer is of course i don't have a problem with quality brand named cells. and i bought my last 2 lots of cells from there. but if i can buy a cell 50p cheeper that doesnt have a well known name and still does the job then i will buy it, 50p to 60p a cell cheaper soon adds up. i built my own battery because i got better quality cells and save some money. so probley gonna save £40 or £50 on a big battery.
as we all know just because something has a brand name, it doesnt always make the extra cost worth while.
Where do these cells come from. ? There will be a limited number of lithium cell manufacturers, with chemical laboratories and QC facilities. They produce cells. As with all manufacture products there will be a distribution curve of performance. .. perhaps when the machine was started in the morning the mixing of the ingredients was a little off optimum, the alignment was going out of kilter ..anyone linked with manufacturing knows that these happen.? In some cases if a few items in a batch are found defective, the entire batch is scrapped., even though 80% might be ok.
There are rumours that in some Chinese factories moonlighting takes place where the machines are used to manufacture without the knowledge of the management
.
What happens to substandard cells or batches? .... often it is not possible or economic to simply strip them apart and recycle the innards They are sold off as scrap value and then resold by third parties... That is what you are buying with unbranded product...