Would this work?

[aqrhine]

I was wondering if you would be able to plug this usb passthrough

$7.51 Variable Voltage USB Passthrough Battery for E-Cigarette at FastTech - Worldwide Free Shipping

Into this usb external battery pack.

$22.24 1A 2*18650 Single USB Output Mobile Power Pack Battery Charger w/ LED Illumination - black / 2*18650 (3400mAh/Panasonic) at FastTech - Worldwide Free Shipping

The only problem I see is that the battery pack only outputs 1amp.

I've seen them with 1.5 and 2amp modes.

How many amps does the pass through require?

 

[Grimwald]

The passthru I use requires 1.5 amps...I use it on a 2.1 amp plugged into the wall socket.

 

[volume control]

3.4V on a 1.8ohm head is a decent vape. At that level you are looking at 1.88~ amps. I would go with a 2A minimum on any passthrough