Hi William,
Thank you for reaching out to us! The iStick 30W has a 2200mAh internal, non-removable battery, so it may not be what you are looking for; however, we do have a number of devices that accept external batteries, and I'm posting the links to a few of them below.
http://www.smoktek.com/Vaporesso-Tarot-Nano-TC80W-Express-Kit_p_1446.html
http://www.smoktek.com/Wismec-Presa-TC75W-Express-Kit--Silver_p_1379.html
http://www.smoktek.com/Eleaf-iStick-Pico-TC75W-Kit--Black_p_1393.html (temporarily out of stock)
Best regards,
Brad