Hi RAH,
The UDT-V14 does require that you remove the batteries to charge them. If you're looking for a device that will give you the pass-through feature with the additional features of a regulated mod, the Eleaf iStick 20W and the Eleaf iStick 30W offer great battery life and performance in a small package.
http://www.smoktek.com/Eleaf-iStick-20W-2200mAh-VVVW-APV-Kit_p_1225.html
http://www.smoktek.com/Eleaf-iStick-30W-2200mAh-VVVW-APV-Kit_p_1262.html
Thank you,
Brad