Hi Bionic
I am sure Imeo will come on later to answer you, meantime, I am no expert, as I do not as yet have a GG of any kind...
I do have other e-cigs though including the Janty Stick.
When that starts performing less, its down to a couple of things, as I am sure you already know, ( but someone who doesnt may be reading also) atomiser, battery or battery charger.
If you know your atomiser is ok. And its definately down to the batteries not holding a charge, then it can be one of two things, batteries or charger.
If you do not have spares of either, then I would think an email to Tim would be the best thing to do.
Although do nothing till you hear from Imeo, as I always tell him, I know nothing of batteries...lol
Dont despair, Im sure its going to be easy to sort out.