Make sure you get protected, high-drain batteries. They are the safest. I vape on a single 1850 all day. They say it's safer to not double-stack your batteries like you can do with 2 18350's. If you use only one 18350 you can take out the extended section and have a more compact device but you will lose stamina. The charger will be the sort you use with rechargables and most places you order from will offer some semi-universal chargers for those. Make sure you don't skimp on battery quality and you buy the button-tops. AW's are good and E-fest aren't bad.
No offense to DeathsMistress, but this post contains several inaccurate statements. Since most of us simply want to vape safely and enjoyably without having to get a P.hD from Battery University, I'll refrain from picking it apart.
I will add the following
suggestions to address some of the OP's concerns:
For single battery function in "full size" mode, you will be fine with:
- AW IMR 18650 (1600mAh or 2000mAh)
- Efest IMR 18650 2000mAh
- Efest 18650 Hybrid IMR 2250mAh
- Panasonic CGR18650CH 2250mAh
There are a variety of other brands of 18650's that would be suitable for use in the Vamo, but the above four are the most widely available for purchase at numerous vape oriented vendors. Button top vs. flat top batteries is a non-issue for use in the Vamo, but I'd recommend button tops when given the choice.
For single battery function in "mini" mode, you will be fine with:
- AW IMR 18350 700mAh
- Efest IMR 18350 800mAh
Again, there are other brands of 18350's that would be suitable, but the above two are readily available and proven to function safely and reliably. Go for button tops when given the choice. Single battery configuration is fine for single coil attys/cartos that aren't being powered at the high end of the voltage/wattage settings accessible when using the Vamo.
For stacked 18350's in full size mode, buy pairs of either:
- AW IMR 18350 700mAh
- Efest IMR 18350 800mAh
Label them in whatever fashion necessary to keep them in use as matched pairs. Stacking batteries in the Vamo is perfectly safe and will provide the power necessary to fire dual coil cartos/attys at higher voltages/wattage.
Finally, all batteries should be recharged with a "smart charger". They are reasonably priced and readily available for purchase. The best three options are:
A resting period of a few hours prior to recharging as well as after recharging is a good practice to adopt.