What does “regulated” power mean for headlamps?

Recently I’ve posted a number of headlamp reviews and during my research I learned something about headlamps that I never even though about – regulated power.  Headlamps with regulated power have additional circuitry that provides a consistent flow of electricity to the LED.

When you are using an unregulated headlamp you will notice a substantial drop in the voltage output of a battery as their juice goes from full to empty. This causes the light output to noticeably dim long before the batteries are spent.  With regulation you feed a constant level of power to the LED and maintain a consistant brightness level. This provides a more useable run time from your batteries.

Something to note: NiCad, NiMh and Lithium batteries have a much flatter voltage curve and don’t benifit quite as much from regulation.

I used to think that lumens was the be all end all rating to pay attention to when shopping for headlamps but now I look for regulated first and lumens second.  This is hugely demonstrated when looking at the Princeton Tec Vizz verses the Black Diamond Equipment Storm.  While the Vizz has a much higher lumen rating (165 vs. 100) the unregulated power in the Vizz causes the effective lumen rating to drop to around 75 after 45 minutes of continuous use.  The Storm, on the other hand, will maintain its 100 lumen rating for over 3 hours before starting to dim (the Storm only regulates the first 25% of its battery then opens it up for unregulated power to maximize battery life for the remaining 75%).

Here's me wearing my Vizz at the summit crater of Mt. Rainier.  While the Vizz might not be ideal for mountaineering it did get me to the top of Mt. Rainier during our early morning summit bid.  Got to give it props for that!

This trip up Mt. Rainier is what initially sparked my interest into headlamps and their power output.  About an hour into my summit attempt I noticed the Vizz I was using was barely lighting my way.  I thought the batteries were dead so I swapped them out – 45 minutes later I was back to hiking in the dark.  Unregulated power had reared its ugly head.

Unregulated headlamps are still good products.  For someone who needs to use one for 15 or 20 minutes at a time – think car camping, biking to work, going on a jog, etc. – unregulated headlamps work just fine.  Where the difference really stands out is when you are doing things like night hiking or pushing an early morning summit attempt, events where you are continuously relying on your headlamp to light your way through critical situations for extended periods of time.

The two headlamps I use are the Black Diamond Storm and the Black Diamond Icon – both feature regulated power output.