This is a guest post written by Morandir835, a regular on V4L's sub forum on ECF, and an e-cig enthusiast. One e-cig piece I haven't explained yet is the passthrough, known by many as a "PT." It's not really a battery, but can be a lifesaver when driving or when all of your batts are charging. It comes in both auto and manual versions, but requires an external power source to run, namely a USB port. Unlike batteries that start at 4.1 volts depending on the model, PTs run at 5 volts constantly. That is as long as they are hooked up to a proper power source. This is where the wall and car adapters come into play. The standard output on a USB 2.0 port is 500 ma, and on a USB 3.0 port is 900 ma. There are ones that run higher, but it all depends on the motherboard manufacturer of your computer. The problem is running a PT with a WOW carto at 2.3 ohms will require 2.17 amps (2170 ma). That's not only a strain on your motherboard but also the 5 volt rail on your power supply. Although extremely rare, this can lead to burning out a USB port on your computer, to complete system failure. I suggest using a USB adapter, rather than your computer to run a PT. In order to run a PT properly, you need a USB adapter that provides at least 5 volts/2 an output. Luckily, V4L sells both. The V4L Car Adapter plugs into the cigarette lighter port of your car, and converts the 12-volt powered supplied into 5 volts. It's rated for 2000 ma (2 a) but in all my tests actually provides up to 2.3 a of current. This gives you plenty of headroom for either WOW cartos or CoolCart cartos. The V4L Wall Adapter is rated for 5.1 v/2/1 a and is built to UL standards. Just like the car adapter, it too provides higher than it's rating. In the ones I've tested, they provide up to 2.4 a of current. The PT has a few drawbacks to keep in mind. Because it requires an external power source, it is not portable. The higher voltage means you have a higher chance of burning a carto if it goes dry. A lot of people will suggest using CoolCarts for this very reason. Their higher ohms and slightly higher fill-capacity decrease your chance of burning a carto. Personally, I use WOW cartos on my PT (and everything else), but again personal preference will come into play like so many things with vaping. Still, there's nothing quite like vaping at 5 volts. Contact Morandir835 via e-mail at [email protected] or through his page on ECF. "Even Though I Nothing Learned, With Strength, I Burned." - Emperor