The 4 "D" batteries that is included in the original box are labeled for LED Lenser's own branding and each comes with 16,000 mAh. Given the long hours per set charge-load, I called off the idea to purchase a separate charger to accommodate just the D batteries. Its cheaper to buy just alkalines than rechargeables in this case. Unless I plan to camp out more than 2-3 months inside caves....

Here's an overview for making one's choice selection. I was also informed, the P7 is a popular model which many or our search & rescue organisations focus on with bulk buyings.

Model K3 P2 P3 P4 P5 P5R P6 P7 P14 P17 X21 T7 Hokus Fo T5
Lumen 14 11 13 14 65 200 80 170 180 190 950 170 80 65
Battery 4xAG13 1xAAA 1xAAA 2xAAA 1xAA 1xAA Lith 2xAA 4xAAA 4xAA 3xD 4xD 4xAAA 3xAAA 1xAA
Reach 6m 29m 29m 29m 90m | 45m 175m 175m 175m >400m 175m 29m 90m