I have a Trustfire 18650 protected battery that I was using in my Ultrafire C2 MC-E light. I unscrewed the head and soldered a spring so I could also use unprotected trustfire batteries in my light. Well I put a protected 18650 in there, and tried to measure the amps with my voltmeter. All of a sudden, the display read like 12 amps of electricity, and smoke started coming out of the battery tube very fast! I quickly stopped what I was doing. Now my question is, did the 18650 vent? I don't see really any residue, but it shows the voltage at 0 on my meter now. I took an unprotected 18650 in my C2 after this and it worked fine. Also, why would the spring make what I described happen? I had everything on my meter set up right to measure the amp pull, and I hooked the Leads up correctly also. The light still works so fortunately I didn't fry the MC-E led.