# extreme cold weather usage for PETZL MYOLITE 3



## capncrunch8942 (Jan 16, 2010)

Hi guys, my and my buddies got PETZL MYOLITE 3 lamps http://www.rei.com/product/720243 at a very discounted price for an alpine mountaineering course that will see temperatures drop to as low as -30C (-22F). We will be spending a month in the middle of nowhere in Sikkim, India.

At these temperatures, what are my hopes for alkalines? what is the temperature point at which alkalines will die on me? 

To get around the cold temperatures, can i use lithium batteries in this headlamp?

How about modding the battery compartment with a very long cable so that i can stick the battery pack in my jacket? any advice or experience on such a modification?

thanks for your help guys!


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## uk_caver (Jan 17, 2010)

From: http://www.petzl.com/en/node/9935



> Do not use Lithium batteries with the following lamps.
> ...
> MYO range: MYOLITE 3 / MYO 3 noir / MYO XP.



What happens in practice when used in very cold areas, I couldn't say - it may be that Petzl are just covering themselves against _possible_ problems.
I suppose mountaineers would be the best people to ask, since they'd have the most experience in the particular environment.

However, if lithiums really were a potential problem, but you wanted to use them if possible, and were otherwise thinking of modifying the light anyway, one possibility that might be worth thinking of is sticking in a series diode to drop some voltage.
I'm not sure how much voltage you'd need to lose to remove the chance of the battery voltage being too much for the lamp, but it might be that even losing ~0.3-0.4V (the drop on a schottky diode) would be enough to take the edge of the voltage.
Adding a diode into the cable (or maybe the headset?) might involve adding less unreliability than modifying the light to use a remote battery pack. If doing that, it could make sense to double-up the diodes as some insurance against component failure, and also to make sure you had a little scrap of wire in your repair kit to bridge the diode in case you wanted to undo the repair.


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## zemmo (Jan 17, 2010)

capncrunch8942 said:


> Hi guys, my and my buddies got PETZL MYOLITE 3 lamps http://www.rei.com/product/720243 at a very discounted price for an alpine mountaineering course that will see temperatures drop to as low as -30C (-22F). We will be spending a month in the middle of nowhere in Sikkim, India.
> 
> At these temperatures, what are my hopes for alkalines? what is the temperature point at which alkalines will die on me?
> 
> ...



Alkalines will just lose more capacity the colder it gets. At 20 below, mah won't be much. If you put a hat over the battery pack that would help considerably, and a remote pack that you could keep under your clothes and next to your body would work fine. I used to use alkaline D cells like that down to 40 below. 

Most likely lithium primary (not lithium-ion) cells would work fine. 

I don't know why the manufacturer would use a halogen bulb in a light like this, especially at 20 lumens. I had a BD Soliras which had a similar set-up, except for a rechargeable Li-ion pack. It was a solid underperformer. 

Have fun in Sikkim. I expect you're trekking up towards Kanchenjunga? I was there for a couple of weeks in the late 90's and loved it.


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## uk_caver (Jan 17, 2010)

zemmo said:


> I don't know why the manufacturer would use a halogen bulb in a light like this, especially at 20 lumens.


Presumably halogen still beats regular incandescent even at the ~20lm range?
Also, they were out too early to have used power LEDs - on the market by mid 2003, and so designed well before then.


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## zemmo (Jan 17, 2010)

uk_caver said:


> Presumably halogen still beats regular incandescent even at the ~20lm range?
> Also, they were out too early to have used power LEDs - on the market by mid 2003, and so designed well before then.



I didn't realize it was such an old design.


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## Egsise (Jan 17, 2010)

capncrunch8942 said:


> Hi guys, my and my buddies got PETZL MYOLITE 3 lamps http://www.rei.com/product/720243 at a very discounted price for an alpine mountaineering course that will see temperatures drop to as low as -30C (-22F).
> 
> At these temperatures, what are my hopes for alkalines? what is the temperature point at which alkalines will die on me?


It depends a lot of the brand and luck, because different brands are made in the same factory.
Energizer or Duracell bought from North America is different than bought from some other continent.

If I was you I would buy a headlamp that uses something else than AAA, AA would be perhaps better choice.
Separate battery compartment is a good idea, but make sure that the wires can handle -30°C without breaking if you move them.
For extremely cold enviroments Energizer lithiums are good, and those are all made with the same "recipe".

vee73 has done tests with AAA in cold, results are found in here, Finnish only sry:
http://www.kuvaboxi.fi/julkinen/2bkam+vesa-aaa-paristotesti.html

vee73 did his tests with 2xAAA direct driven penlight, for tests in cold the penlight is freezed in -19°C for 9 days.


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## uk_caver (Jan 17, 2010)

The Myolite 3 is a 3xAA light.


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## Szemhazai (Jan 17, 2010)

*capncrunch8942*, I have observers experience on Myolite3 - few times I have seen people using them when they start in night competition, for their first time - mostly after three hours they were looking for somebody with a working headlamp, because they were out of power.


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## paulr (Jan 17, 2010)

Chances are, the higher voltage of lithium will blow the bulb faster. Maybe you can substitute a lower voltage bulb.


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## Egsise (Jan 17, 2010)

uk_caver said:


> The Myolite 3 is a 3xAA light.


Dang, sorry my bad!
AA tests in cold can be found from my sig.


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## Micro17 (May 26, 2014)

Once I used a MYOLITE 3 in led mode continuously for 10 hours in a cold environment (approx -10C), lots of fog and snow. The batteries were NiMh AA Sanyo Eneloop, 2000 mAh.
No surprise here, since its 20 lumen output draws no more than 30mA (I measured the current once). Pretty efficient for its age.


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