Thanks everyone for the replies & great advice!
Nightshard, I think the charger must be bad. It's the Kamry one I got with the K103. After I bought the brand new Sony 18650. (2100) I put it in the Kamry charger & the next morning (~12hrs) it was still not green.
Yesterday morning I put the Kamry 18350(900) in the kMry charger & 8 hours later even that was not charged.
Nightshard, I think the charger must be bad. It's the Kamry one I got with the K103. After I bought the brand new Sony 18650. (2100) I put it in the Kamry charger & the next morning (~12hrs) it was still not green.
Yesterday morning I put the Kamry 18350(900) in the kMry charger & 8 hours later even that was not charged.
18650 doesn't take 13 hours to charge.
There are several possibilities:
1. Your charger is defective.
2. Your battery is defective.
3. You over used your battery dropping it below 2.5V and by doing that ruined it.
First of all take a volt meter and test your battery voltage.
Which charger are you using?
You need at least 2 batteries so you could charge one while using the other.
Get to know your batteries and don't over use them.