18650 with high self discharge?

I have four Efest 18650's of this the model is rated at 3000mAh with 20A continuous discharge and 35A bursts. They are unprotected flat tops. I bought all four at the same time from the same vendor. They have between 75 and 100 cycles. One of them has developed a very high self discharge.


I did this test three times. Charged all 4 let them sit in a box for 2 weeks the checked the voltage. Three of them had voltage >4.1V and the other had 3.5V. I did a capacity check on all 4 right after a full charge and they all were about 2750mAh and they all can deliver 10A and not get hot. I don't have any test equipment that can discharge at greater than 10A unfortunately. The IR's on all four are also very close and under 80. It seems to me like the battery has it's capacity and it's discharge current at least close to when it was new but the self discharge is the highest I have ever seen for this chemistry.


Has anyone else had a battery wear out like this? This is a first for me.


Thanks in advance


Frank

Sounds like it might have an internal short.

I myself would quickly Get Rid of It !

Don't give that questionable cell a chance to FAIL !

< just sayin' . . . . >


_

Yeah, at that rate of discharge, you might actually be able to feel the cell is slightly warm to the touch. At least for the first day after charging. (Self-discharge probably slows down as the voltage gets lower.) There's probably a short through the separator inside the cell. Get rid of it.