Just wondering - big difference in charge time

[Train2]

I have one Efest IMR 181650 LiMn battery.
Got it new, it looks exactly like this image below.
It takes like twice as long to charge as my other 18650 batteries!
(including AW IMR, CGR18650CH and NCR18650PD)
Any reason/explanation or cause for concern that it takes longer to charge? Performance seems fine otherwise...

 

[Switched]

You didn't give us much to go on ??? e.g mAH of each of the depicted cells.

A wild guess regardless of how new they are, internal resistance.

 

[Train2]

That eFest is 2250. Don't know internal resistance...and can't measure it.


I'm comparing to
Panasonic CGR18650CH, also 2250 mAh
Panasonic NCR18650PD, 2900 mAh
and AW IMR 18650, 2000 mAh

 

[Ryedan]

The mAh (milliamp hour) rating is how many milliamps the battery will discharge when it's completely discharged in one hour. Just like the amp hour ratings on our car batteries. The higher that number, the more energy is stored in the battery (and should be taking longer to charge, all things being equal).

Chargers charge these batteries for the first about 2/3rds of the charge using a set number of milliamps. Some chargers let you set that and some don't. Then the charger slowly lowers the current until the charge is complete.

Assuming you used the same, good, charger and discharged the batteries to the same level, say 3.3V each time, the battery with the highest mAh rating should be taking the longest to charge, the NCR18650PD in your case.

So first off, are you using the same charger for all the batteries? Are the batteries about the same voltage when you put them on the charger? If you're not sure about that, are they all being used in the same PV and if not which batteries are you using in what? Also, are the batteries about the same ~4.2V immediately after charging?

 

[Train2]

I get the battery basics, and this seems unusual, that's why I ask - whether there's something else that determines charge rate.

Yes - all batteries are getting charged from about the same level 3.4 (+ or - 0.1 v). All are reading 4.2 when charged. All charged on a Nitecore that's never given any hint of trouble.

With the slight difference in mAh, I'd expect a slight difference in charge rate. And I understand a battery's got an internal resistance than can effect both performance and the charge rate. But the eFest literally takes almost twice as long as others, which surprised me.

 

[Switched]

... its called battery chemistry. Albeit the Efest do well out of the gate, it is a known fact they fail in the stretch. "Internal resistance"