hey e-pipeman,
something funny -- on the Janty World USA site, they advertise it as a passthrough.
but on the Ivapour (UK) site, they advertise it as a USB battery. then on the last line of the product description, they mention that a 1.5m cord comes with it, yet they don't even touch on the word passthrough.

Anyway, I'm going to put this to rest, as it is evident that when the battery expires, you just order another passthrough when in the USA, another USB battery when in the UK -- simple as that.

The reason I asked for help from ECF on this is because every time I eMailed Ethan at Janty (3 times), it always took him a full day to a day-and-a-half to get back to me. They either have the poor guy overworked, or he could be on vacation with only his laptop with him.