I'm using a Sigelei J150 with 18650 3.7v 3000mAh batteries. Today I noticed when I hit the firing button, the battery indicator and volts seem to drop about 25% (haven't noticed this before, but I also don't see the screen when I'm firing of course). Is this a normal thing? Does this mean my batteries are starting to die? I have had these batteries for almost a year now so I wouldn't be surprised if they were dying. I also just recently put in a new coil, but I don't think that has anything to do with it. Any help would be great. Thank You. There doesn't seem to be a drop in cloud production, so I'm hoping this is a normal thing.