Backups are always a good idea and there are lots of good suggestions above. I wouldn't jump to a 200W mod from where you are now, but if you do want to upgrade, I would suggest a mod that puts out 50 - 75W. It will have a bigger battery capacity and will last for days on a charge with the tanks you are currently using. If you ever decide to upgrade your tanks, it will have enough power to carry you through 1 or 2 more steps as well. If you want to keep using your current tanks, you might need 510/eGo adapter. Most of the iStick mods come with one. Also be aware that the higher power mods don't always have the option to fire at really low wattage. Most of the big boys won't go below 7 - 10 watts, and they tend to put out more than that even when you set them that low.
If you don't think you will ever want to chase bigger clouds, there are still better devices that you can pick up for about $20, but they use 18650 batteries so consider the cost on that. Batteries are around $6 - $7 each and a charger will run you about $20. These mods won't require an adapter for your eGo tanks:
Zmax V3 Kit by Sigelei $19.99
VAMO V5 Kit $19.99
Good place to get authentic batteries cheap. Get at least 2 for a single battery mod or 4 for a dual battery mod so you won't have to stop vaping when your battery dies. These are some of the best batteries for use at 85 watts or less.
LG HG2 $6.99 3000mAh High Drain IMR Battery INR18650HG2
Very decent charger. Not the best, but good. Any charger will work, just make sure it's not one of the cheap ones that plugs directly into the wall and has a single LED light on it.
Efest LUC S2 Charger $22.95 - Charger - Accessories
If you don't think you will ever want to chase bigger clouds, there are still better devices that you can pick up for about $20, but they use 18650 batteries so consider the cost on that. Batteries are around $6 - $7 each and a charger will run you about $20. These mods won't require an adapter for your eGo tanks:
Zmax V3 Kit by Sigelei $19.99
VAMO V5 Kit $19.99
Good place to get authentic batteries cheap. Get at least 2 for a single battery mod or 4 for a dual battery mod so you won't have to stop vaping when your battery dies. These are some of the best batteries for use at 85 watts or less.
LG HG2 $6.99 3000mAh High Drain IMR Battery INR18650HG2
Very decent charger. Not the best, but good. Any charger will work, just make sure it's not one of the cheap ones that plugs directly into the wall and has a single LED light on it.
Efest LUC S2 Charger $22.95 - Charger - Accessories
