For those of you who are the prepper types, I've got a recommendation for what I think is the ultimate backup device. Whether just somehow caught between charged batteries, or (worst case) some months down the road after the FDA bans everything and all of your mods have died.
It's an adjustable voltage USB pass through for just $5.50. It's not quite VV but you can set it for 3.2 V / 3.7 V / 4.2 V / 4.7V (web site has typos).
I bought 3 of them and they work great. I figure one for the car, one for the kitchen, and one for when the apocalypse comes. My laptop powers the kitchen one just fine for the first 3 voltages but for the highest voltage I need to have a higher ohm atomizer.
If where you have it plugged in can't handle a certain higher voltage / low ohm combo, it will just blink and switch back to the lowest setting. If you want to get the absolute most from it, or not risk your laptop, you can buy a 2 amp USB wall adapter or car cigarette lighter adapter, also available at this and other sites. The prepper in me bought one of each.
It's nothing more than a 510 connector, a standard ego type button, and a USB cable. Even has ego threading for your eVods & T3's. But I'd recommend using the 2.2 - 2.4 ohm heads or higher.
This place does take a week or 2 for your stuff to arrive and they have a holiday coming up (details on site). Most other places sell these for $15-20. For $5.50 you can buy several for the apocalypse or even give them as gifts.
https://www.fasttech.com/p/1353300
