Got my first bunch of protected 16340’s the other day. All arrived with a charge of 3.7v and a stated nominal voltage of 3.6 v on the wrapper. I charged them in a Sysmax i4 charger and they stopped at 4.2 volts and then bled down to 4.15 volts. Is that normal?
Do I need to “groom” these batteries or break them in? I am familiar with 18650’s and the Li technology, but have never used the 16340’s so I am unsure whether this is abnormal behavior.
All 8 of these seem to charge up to 4.2 then bleed down to 4.15 within an hour or so.
I’ve found the same thing with smaller LiIon cells too. Both my 14500 and 16340’s will drop to 4.15-4.17 after a day or so.All my small cells are AW and even the IMR versions do the same thing.I have not been that impressed with the smaller cells due to this and they just don’t seem to be as consistant as 18650 and 26650’s.I do have a pair of ultra-fire grey 14500’s that have been retired…they were really bad(not even the same length).The cheap 18650’s are bad enough, I wouldn’t dare use cheap 16340 or 14500’s.
of a small battery is probably on the order of 10 minutes, with ~one hour to stabilize at room temperature so there must be some other effect at work here.
Termination current is too high, it should be capacity/50 to capacity/20.
Your charger most likely terminates somewhere around 100mA, which is fine for 18650 - C/50 = 50mA for average 2500mAh cell, C/20 is 125mA, so 100mA is well within this range.
Yet for 16340, nominal capacity of which is most likely somewhere around 600mAh, termination current should be 600/50 = 12 to 600/20 = 30mA.
There are no disadvantages for a little high termination current, apart from cell getting slightly undercharged (for some, this is an advantage, because cell will last longer when undercharged).
If you charge in a non-terminating charger like the TrustFire TR-001, they will top up fine. It’s still (basically) safe to use, just take them out after a few hours.
I will note that almost anything other than 18650 is based on a second-rate technology. The state of the Art is in 18650 because billions of them are made every year. The other sizes are considered specialty and do not get the R&D effort so they are stuck in the battery ‘stone age’. Sad but true.
