sunwayman m10a - brightness

i have a new sunwayman m10a aa light. it has 3 brightness settings. I think the 4 lumen setting is great for looking at maps while on the trail - you can check the map without blinding yourself. in addition, at the campsite 4 lumen is just right fro most tasks. when i hike at night the 40 lumen setting does a nice job at lighting up the trail.

Amazingly i can go on a 3-5 day trek and 1 battery is all i need - fantastic.

Here's the rub. I just don't see that much difference between the 40 lumen setting and the 140 lumen setting. i use a regular alkaline duracel battery. is there perhaps a better battery that i should be using? i expect to see a notable difference between the 40 lumen and 140 lumen setting and i really don't see one.

Ideally, you should be using a NiMH rechargable (eneloop is the recommended brand) or lithium AA. Alkaline batteries die rapidly under high load like the light needs for the 140 lumen high mode, while the other chemistries can provide the needed current.

I tried a lithium battery and noticed an improvement. the problem is that these batteries are expensive. I was thinking of getting the eneloop 2500 mAh batteries. Does anyone know the burn duations for these batteries? I know that for an alkaline cell I can get 10 hours @ the 40 lumen setting. How does the eneloop perform?