Based on some strong recommendations here, I recently ordered two Fenix L2D Premium flashlights as an upgrade to my L&M Vega. However, one feature I liked was the Vega's low battery indicator. The Vega has a handy green light that blinks when the batteries are low and automatically switches to a lower setting to conserve battery life, before outright dying. I've yet to run a set of batteries dry on the L2D Premiums and I'm wondering if there's any indication that the batteries are weak before the light switches off?

I've read that the Fenix P3D flickers before dying. Does the L2D Premium do the same? Or does the light autmatically switch to a lower setting when the batteries are weak? Although I plan on carrying spare batteries, I'm worried that the light suddenly will die without warning, which could lead to some hairy situations. Any advice or information is much appreciated.

Put some Old Batteries in the light and see what happens.

I have an L2D Premium Q5 and it certainly does die without warning. I didn't notice any flickering or anything, it just seems to crap out. Like 10 Wheels said, put some old batteries in there and see what happens. It will turn on and be really dim then get bright for a second or randomly switch to other settings and do other funky things. The first time it happened I thought it was broken, but fresh batteries brought it back to normal.

I've almost had a couple of hairy experiences on dark, rainy nights due to running out of battery juice, but fortunately I was able to swap the batteries with the ones in my secondary headlight (Blackburn Quadrant).

If you are using two lights, it's very unlikely that they will both shut off at the same time. So, if one light does run low and turn off, you should be able to see well enough with the remaining light to pull over to the side of the road and replace your batteries.

The lack of a low-battery indicator is the only drawback I have found with my Fenix light. I've gotten in the habit of periodically waving my hand in front of the light to make sure it is still charged. It's gone dead several times during rides when it was light enough outside that I didn't notice until I reached my destination. However, I like to run my front light all of the time while commuting for visibility.

Dourbali Star, I suggestion you two Fenix. One for Turbo setting, other Fenix set for second highest powers.
L2D is dying suddenly when powers low. Sos sad.

I think the L2D intentionally is designed to drive the light at full brightness until the battery is out. If you are going to be riding a lot at night, just stick a couple of spares in your seat-tube or something.

The light will dim gradually as the battery weakens. If you are in turbo mode it will go to the next brightest mode and so on until it dies.

Mine also just rapidly goes to zero after being at full turbo power. I prefer this to a long slow waning of the light. As others have said, just have a second flashlight, or a second set of (rechargeable) batteries and no worries.