Rechargeable options for Fenix P3D?

[ImGeo]

What are my options for rechargeable batteries for the P3D? I know I can use 2xRCR123, but the runtime is somewhat poor. So... would 17670 work, or possibly 18650? Any comments and advice is much appreciated.

 

[SuperTrouper]

What are my options for rechargeable batteries for the P3D? I know I can use 2xRCR123, but the runtime is somewhat poor. So... would 17670 work, or possibly 18650? Any comments and advice is much appreciated.

I'm not sure about the other options but I know an 18650 physically will not fit in a stock P3D.