I third the ipv3Li or the ipvD2. I am not sold on the new Sigelei/Snowwolf chip. I have the 50 watt version, and it is not as refined as the YiHi chips (as in the ipv's) If you are using it at 110 watts or lower, Samsung 25R or LG HE2/HE4 are the most economical, but the LG HG2 will last longer. If yo are at 150 - 170 watts the Sony VTC 4 or LG HD2 would be the safest choices, but will not last nearly as long. Over 170 LG HB6 or Sony VTC 3. Here is a couple good sources for batteries, I have always got good batteries, and service: Illumn or Liion Wholesale I agree with squid on the charger, the LUCV4 is a great charger, the Xtar VC4 is also good, or the VPC4. The nitecore is also a solid charger, but it is a bit slow.