The Sanyo (Panasonic) 24V Lithium battery pack is rated at 9aH (amp hours), is lightweight (about 8 lbs), lockable, and easily removable for storage or charging.
The Twist Express has a sturdy rear rack designed to accommodate 1 battery pack on the right side and a storage pannier on the left side. The Twist Freedom DX has the ability to accept 2 batteries for added distance capability.
(Left) The rear view of the rack mount which holds the battery and pannier appears have substantial tubing which forms the support structure. It also looks like it could easily hold another storage container on top as well. (RIGHT) Battery locking mechanism appears to be well integrated and sturdy.
Once unlocked, it's a simple matter grabbing the handle and pulling to release the battery from the docking station. There are no wires to disconnect as the power connections are at the bottom, and securely made while inserting the battery.
The pannier, though not particularily sizeable, may meet the needs for a casual trip to the coffee shop. However, if a larger load is to be carried, it may be necessary to replace the supplied side bag with something larger (custom install), or possibly a top mounted bag could do the trick. Although it does appear to have some expandability, often referred to as gusseting, it does not. The total weight capacity of the rack is 35lbs.
Notes:
1- The Giant Twist Freedom DX would have 2 batteries instead of a battery and pannier as does the Express.
2- The manual clearly states that the battery MUST be removed for recharging.
3- The 6 month warranty on the battery BEGINS when the bike is purchased.
4- Think twice about mounting a baby carrier to this rack, mainly because there is a weight limitation, and Giant could void your warranty. However, I did not see anything in the manual / warranty that excludes towing a trailer, as it is fastened to the frame; check with your dealer. Read the manual for contacts and clarification.
For more information on Giant's products please visit their website, or an authorized dealer.