First off I believe the OP was looking for something that wont allow you to change batteries also, I'm not completely sure. Personally I prefer the ability to change my batteries. I suggested the VTC mini to let them look it up and maybe see there are advantages to doing this.
For the mod (the box the batteries go in), I'd recommend something that holds two batteries and will give you at least 75 watts of power. Not only is the TFV4 thirsty, it's power hungry, and you won't get much life out of a single battery device. I'm using an IPV d2 and a Crown tank (in the same league as the TFV4, maybe not even as demanding though), and changing my single battery out every hour or two.
Here is where I have to ask a question. I see a lot of posts like this and not really sure why people are having to change their batteries out so often unless they are chain vaping (I do this when I am at home and just messing around on the forums or something), running lower than needed ohms and just pushing the wattage (this is where I see a lot of other posts of people pushing way low ohms and dumping tons of wattage into the hardware).
When I am at home I can use my dual battery setup and chain vape my brains out, when out and running around I don't personally care to have a dual battery device, it's bulky and over weight to have to carry around and I much prefer a single battery device for putting into my pocket. I have the Crown and I have the Crius, the Crown is a single coil setup while the Cruis and the TFV4 are intended dual coil but can be ran in single. When running around and using my VTC mini or my Sigelei 50w V2 (both single batt. devices) I don't have the time to chain vape and I build my coils to come in at around .6-.7 range and still get plenty of vapor and flavor at 25-35 watts, this lets my batteries last plenty long enough to get back home or even if I think there could be and issue I can carry a spare batt. in my car or other pocket if I am at work and it is still a much smaller setup than carrying a dual batt. device.
OBDave, don't take this post as trying to bust your balls, that is not what I am trying to do. I just honestly do not see why people feel they need to run these devices at such high wattage when I can find a VERY pleasant vape on much lower wattage and not chew through batteries as much.
Lets take a look back in time. Lets go back one year and look at what everyone was running their wattage at, now lets go back two years. People where very happy with what they where getting back then and I really think a lot of this has more to do with the chips that are being released, people see the wattage they can push these devices to and do it with no appreciable gains that I am aware of. Maybe I am just missing something who knows.
