No Power, Battery tests good

[lavenderloins]

I am having a bit of a unique problem with my bike. It has sat for a bit, and in that time the battery had died. I hooked it up to the charger on the 2 AMP setting, and let it charge until it said it was good to go. I turned the key, had lights and power. Went to start it and it made a light pop sound under me, and from that moment had no power. I have checked the 20AMP fuse by the battery, it is good. I have tested the battery at the local autoparts store, it is good. Even if it wasn't charged all the way, I should still get dim lights, right?

Here is the weird part: I get power on the bike if it is hooked up to the charger. Obviously not enough to turn it over, but the lights come on, I get ignition, everything. How is it that my battery can test out good and be fully charged, but not even give me dim lights, but when plugged in I get power? I clamped the negative lead of the charger to the block, and to the frame while running, and each time lights came on, then turned off the moment I took the clamp off.

I am just lost on what in the world is wrong with this thing. I can't find any melted connections, or bad wires. Everything looks fine. What am I missing?