I got my new ProVari 2.5 on Friday after waiting a week for it to get here. The AW 18650 that I bought with it wouldn't power it up at all. The 18490 would work, but only if I fiddled with it. The Efest 18650 that I already had worked fine though. I emailed them and told them about the problem and they answered pretty quickly. They told me to clean the contacts and threads on the caps as well as pulling on the spring. I did all that and I got the 18490 to work flawlessly, but no matter what I did the 18650 would not power it up. I emailed them again and they told me that they thought it was best for me to send it back in and have them look at it. I really, really, really, really hate to send it back to them since I have only had it for a few days and I LOVE IT!!! (With the exception of the battery issue of course.) So I guess tomorrow it will be sent back and I just hope I get it back as soon as possible. I will definitely say that the customer service is top notch and they seem to take care of you. So I will be going back to my other mod's and going through ProVari withdrawal for a while.....booo hoooo!!!