Great Advice. Your comment led me to Streamlight.com, which had this comment in the FAQ:

Q: Can I use rechargeable CR123 batteries in any of the Streamlight flashlights?

A: No. Streamlight products are optimized and the components can be damaged or destroyed by the use of anything other than the recommended battery type. The use of improper or substandard lithium batteries can be especially dangerous.

I guess we use alkaline batteries.