I love my Sigelei 150w and would highly recommend it. With a dual battery mod, you'll need to get new
batteries and pair them; mark them in a way you use the 2 paired batteries together and charge them at the same time, and it helps to rotate the side where the battery goes, so after recharging, swap their positions on the mod. I like Illumn.com for my batteries, and for a charger I use the Xtar VP4, which I would also recommend. I use Sony VTC4 batteries, and would recommend getting at least 4 batteries so you can have 1 pair recharge while another one in the mod, but 6 or 8 batteries, 3-4 pairs, would probably work best to give your batteries more downtime.