A couple of notes on the Li-ion 18650 batteries, charging, and the Rim-C power mod (more experienced users, please correct and add!):
1) External chargers, while slow, are considered to charge more completely and are healthier for the battery itself. That said, I frequently just charge within the Neo for convenience, and will accept the consequences of a shorter usage time.
2) The Neo's power mod is capable of quick charging (Qualcomm QC3.0) at 2.4 amps. The actual charge time will depend on the output current of your wall plug or computer. At 2.4A, it should fully charge an "empty" 2400 mAh battery less than an hour (less, because they're never fully empty). At 1.0A, it will take ~2.4 times as long. Some wall plugs are only 0.5A, so those would take ~4.8 times as long.
3) Eleaf's safety protocols allow for the mod to be used during charging (with a long cable). Out of an abundance of caution, we do not recommend that you do this.
4) Buy a reputable battery brand Samsung, Molicell, Vapecell (new brand, but getting solid reviews)...
5) The battery compartment is tight. Some batteries might not fit. 65mm +/- 0.5 should fit fine. 66+ probably won't fit. We had problems with a couple of Sony/Murata batteries due to their length.
6) When inserting the battery, holding it relatively flat while putting the + side in first seems to work best.
7) The charge capacity of all Li-ion batteries degrades over time. So, you might eventually notice that the usage time per charge begin to get shorter.
Cautions and safety notes:
- Do NOT overdrain your battery. If it falls below a certain level, it will not recharge.
- NEVER short circuit... while that might sound exciting, these are high discharge batteries and it's dangerous. Be careful where you put it when not in use.
- Beware of high and low temps. Never allow the battery to be in freezing temps, nor direct summer sun.
- If the battery looks swollen or damaged, do not use.
What other recommendations do folks have?