By Louis Dawson

Larry chooses the Ion headlamp over all others. "Light is right," he says, "especially for fly catching."

I've lost the battle. For a time, I thought I could standardize all my backcountry electronics to use AA batteries. That way I'd always have spares to swap around between devices, and have one less thing to think about while packing. Then along came LCD headlamps. Super lightweight. Long battery life. Reliable. But who knows what kind of battery you'll end up with.

Last year I tried an LCD headlamp that ran on AAA cells. While spare AAA cells are easy to carry, you can't get AAA cells in a lithium version -- essential for cold weather use. For the issue of interchanging spares I tried an upsizer that lengthened the AAA cells so they'd fit inside an AA battery bay. That worked for my 2-way radio, but the smaller cells wouldn't power my digital camera. All things considered, I was less than enamored to AAA batteries -- especially in a headlamp.

Ion headlamp internals, with Duracell lithium battery. Penny for scale.

Fortunately, along came the Black Diamond Ion. This incredibly tiny headlamp floats on my scale at 1.1 ounce (with battery), is ludicrously small, and runs on a tiny 6 volt battery that's available in lithium (Duracell PX28L). This battery is so small that carrying a spare is not an issue, but it packs a wallop: burn time with lithium is at least 17 hours of light bright enough to see the trail while you're hiking or skiing, and a few hours more of dimmer but useful light. Moreover, this baby is so lightweight, you can easily carry a second unit as a spare (instead of a penlight, as many people do).

What's not to love? Keep in mind that this lamp is not intended as a flame thrower you'd use for night rescue or complex technical climbing. Changing the battery is somewhat fiddly, as it probably has to be for a device this small. Perhaps the biggest downside to the Ion is that batteries are expensive, and as far as I know this size battery is not available in a rechargeable. Quibbles aside, I give the Ion a thumbs up as the most useful lightweight headlamp yet. Proof: we've outfitted the whole family with the little chiclets, including Larry.

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