The MV1's battery pack is wired in series (-[1]+-[2]+) so the output of the pack is 8.2V (4.1x2) - this is going to go down as the batteries are used-what reflects the charge indicator on your unit. Then when you recharge it goes back up. It says it's 9 amps peak output on my pack.
My pack also reads 5V 0.5A (USB) but the 0.25A that Nerissa
@ghostvapesofficial stated earlier is probably what the battery pack is actually pulling through the cable. *think it's actually somewhere between that - calculator works it out at 0.39A if it takes 8 hours to charge a 2600mah pack.
Plus being totally honest if Ghost are really doing a 1 year warranty on their battery packs I wouldn't argue with that at all. In most places batteries are considered consumable products and come with no warranty, it's like car tyres or stylus' on turntables, their use is wear and tear. Some vaporizer companies offer warranty on their batteries but I've never heard of a year? That's worth the price of the pack right there for me- I was expecting much less life out of the pack and even less warranty. We'll see.