I guess you are talking about the little USB charger that you screw a battery into (the USB plugged in Bloog doesn't have a light on it)?
When I plugged the adapter into the wall socket, it has a teeny red light. When I plug the USB adapter into it, it's a red light too. When I screw a battery into the end, the light changes and turns green, and the light comes on at the very end of the battery that was screwed into it. When the battery end goes off (roughly 2 hours or so), it's fully charged, so you can take that battery off and screw in a different battery.
The colors on the adapter may be different.... I got an itaste MVP 2 for myself, and my husband took all the Bloog stuff to work with him, so I can't look at it now to tell you the colors of the lights... but what matters is if there's a light at the end of the cig battery you screwed into it. If the light's on, it's still charging, if the light comes off it's finished, full of charge and ready to use. Hope that helps
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Oops, forgot to add that when you SMOKE from that battery, every time you take a drag, the light comes on at the end to show that it's working. When the battery is low, it's supposed to flash a few times instead of being a solid light. I doubt it would hurt it to recharge when not fully discharged, I THINK they are lithium ion
batteries, you don't have to run them out completely before recharging (like a cellphone).