Burn Time for Headlamps

[Arthur]

i tested my Black Diamond Ion for burn time and was unimpressed on two fronts.  I used new lithium and new alkaline batteries.  Both had almost identical burn times of 4 3/4 hours.  Most lithium batteries that I am familiar with have 1.5 x the mAhs of alkaline.  For instance, my GPS units last considerably longer with lithium.  As I would sarcastically expect, the advertised burn time on high for this light was 6 hours.  Ideas on why the identical performance of Li and Alk batteries?

 

[Jerry Adams]

random google search http://www.ultrunr.com/battery.html – run time of Lithium 4 hours, alkaline 3 hours – not that much difference – close to consistent with your results

if there was a 50% improvement it would be 4.5 hours vs 3 hours.  You’d have to test a bunch of batteries to make sure it wasn’t just a particular battery that wasn’t as good…

maybe there’s more difference on higher current applications like a GPS

Lithiums are also lighter and have a long shelf life in case you don’t use your headlamp very often

 

[Rob]

Take that light out into below freezing temperature and repeat your testing.  I think you will see where the lithium batteries shine (pun intended).  In cold weather alkaline batteries will run out of gas VERY quickly while lithium will be minimally affected.

[JCH]

Interesting results but agree that more, and more varied, testing is needed to have confidence in these results.  I have always just accepted as truth the marketing that Lithiums last longer…almost never a good way to go.

As Robert pointed out, for me the true value of Lithiums is the reduced weight and increased cold performance.  Also, I only use headlamps that are regulated which IME perform better with Lithium batteries.  I much prefer regulated headlamp’s steady performance at the cost of a rapid fall-off…that’s what a set of spare batteries are for :)

[David Thomas]

From what others have written, I understand lithiums also get some of their purported much longer life in intermittent high-current applications (camera flashes, for example).  10-50 lumens LEDs aren’t very high current.  Maybe with a 1000-lumen flashlight, the lithiums would have more advantage.

I can confirm, from much personal experience that lithium batteries do far better at cold temps.  When you REALLY want a light – say, flat tire at -20F – you really DON’T want to stick it in some body orifice to warm it up.  Therefore, the LED flashlights in all our cars have lithium batteries in them.

And for backpacking use, even though they cost more, lithiums are an easy way to make your headlamp weigh less (a nice thing when it is on your head), save total weight, have longer life, and better cold-temp performance.

[DGoggins]

Right….same difference with alkaline vs nimh batteries in flashlights ( and vs  lithium ). ->

http://www.candlepowerforums.com/vb/showthread.php?367081-Comparison-of-AA-battery-chemistries

Basically…at high amperage (high lumens), something like an eneloop will do much better than an alkaline, and I’ve read somewhere that a low lumens the alkaline will actually have better runtime than an eneloop though most Manufacturer charts still show a eneloop having better runtime (like the fenix hl 10 -> https://www.fenixlighting.com/product/fenix-hl10-headlamp/)

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