Education Log: May 4, 2000
"High Altitude Head Lamp"

Climbing at night on the final summit push poses a problem for climbers. They need to light the way but still keep their hands free to handle ropes and other climbing equipment. The solution is a headlamp, but how do they keep batteries working in the cold and how can the climbers ensure that their head lamps last the whole night through?

Education Program More on WLEDS More on Batteries Dr. Irvine-Halliday's research Activities "Nepal Light Project" "Design a headlamp"

Normal batteries suffer a very great reduction in output performance in cold temperatures simply due to their fundamental chemistry. For example, you'd usually notice a drop in load voltage and in the total amount of energy they can supply. In order to keep the batteries as warm as possible, most climbers will carry their head lamp batteries in a pouch on a tape around their neck inside their climbing suit.

Climbers can also purchase batteries which are specifically designed to operate reasonably well at relatively low temperatures. Needless to say, these batteries cost a fair bit more than the 'normal' ones.

You may be interested in my "Made in Calgary" solution to our climbers' need for a head lamp which will not only last the whole summit push but also have a huge reserve, just in case of emergencies.

Photo of an LED, theledlight.com

First, I borrowed from the work I have been doing on the "Nepal Light Project," the design of ultra reliable and extremely energy efficient White Light Emitting Diode (WLED) home lighting for the "Developing World" (the primary reason I am in Nepal).

Using that knowledge, right here at Basecamp, I designed a WLED head lamp for Tim Rippel which gives him the choice of 2, 3 or 5 WLEDs at any time. The 5WLED will give Tim about 15 hours of continuous very bright white light and with a much better projection than the conventional incandescent bulb.

The 2WLED or 3WLED will give him correspondingly more hours of reliable operation (WLEDs last virtually for decades - even when used continuously).

For the head lamp I used a very special low temperature rated sealed lead acid (rechargeable) battery which, even if worn outside Tim's climbing suit, would still function many times better than the normal ones. Tim will carry these batteries in a pouch around his neck jsut the same, in order to optimize their effectiveness.

I think we have a very interesting situation here since when Tim summits he will, to the best of my knowledge, be the FIRST climber ever to have climbed Everest using WLED lighting.

Namaste,

Dr. Dave Irvine-Halliday
Education support at Basecamp