Headlamp Problems - Petzl Myo XP

I recently went backpacking and I took along two Petzl Myo XP headlamps that I purchased probably around 2006 or 2007. Even with brand new batteries in them, the headlamps would turn on very brightly for about a minute, then the low light battery would go on for 10 seconds, and then the headlamp would shut off altogether.

Anybody seen anything like this with either this model or another Petzl model? I've never had this problem with them before, and found it extremely odd that BOTH of them did this at the same time. I hadn't used the headlamps in 6 months or so.

I definitely learned something from this experience - never buy two of the same headlamp and always carry a (lightweight) spare headlamp!

Still sounds like dead batteries. Were the rechargable batteries?

What kind of batteries are you using?

Any rust on the contacts?

Are the contacts loose?

Did the battery or any parts get suddenly warm?

Weird? Full moon? Are you a wizard? Wizards and technologhy don't mix.

Just found this link, short circuts?

http://www.light-test.info/index.ph...myo-rxp-2-2011&catid=37:faq&Itemid=41&lang=en

Kind of battery could be a major factor here. Different types of batteries have different voltage drop-off curves as they drain, and the low-battery technology in the headlamp has to understand them correctly.

That said, 10 minutes is still awfully short to trigger *any* kind of low-battery condition unless the battery is simply too incapable of providing the necessary power, such as NiMH rechargeables with too small a mAh (milliamp hour) rating.

roadtripper said:

I recently went backpacking and I took along two Petzl Myo XP headlamps that I purchased probably around 2006 or 2007. Even with brand new batteries in them, the headlamps would turn on very brightly for about a minute, then the low light battery would go on for 10 seconds, and then the headlamp would shut off altogether.

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What kind of batteries? (Alkaline, lithium, NiMH, NiCad?)

Anybody seen anything like this with either this model or another Petzl model? I've never had this problem with them before, and found it extremely odd that BOTH of them did this at the same time. I hadn't used the headlamps in 6 months or so.

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The fact that it happens to both units identically and simultaneously suggests that you are doing something wrong. LED headlamps are pretty simple and 2 units are unlikely to fail at the same time (although it is possible). They have probably been used different amounts of time.

I definitely learned something from this experience - never buy two of the same headlamp and always carry a (lightweight) spare headlamp!

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Getting units from different production runs is a good idea for some pieces of gear but is probably unnecessary for headlamps.

Doug

MichaelJ said:

Kind of battery could be a major factor here. Different types of batteries have different voltage drop-off curves as they drain, and the low-battery technology in the headlamp has to understand them correctly.

That said, 10 minutes is still awfully short to trigger *any* kind of low-battery condition unless the battery is simply too incapable of providing the necessary power, such as NiMH rechargeables with too small a mAh (milliamp hour) rating.

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Any of the standard battery technologies should power the headlamp for much longer than 10 minutes if the batteries are fresh or fully charged.

Either there is a problem with the batteries or there is a problem with the headlamps. The fact that it is happening identically to two units suggests a systematic problem.

BTW, this headlamp can overheat and/or be damaged by lithium batteries (warning from Petzl). (High power LEDs generally include temperature sensors and the circuitry should reduce their power level if they overheat.)

REI listing:
http://www.rei.com/product/721995/petzl-myo-xp-led-headlamp

Detailed review:
http://www.flashlightreviews.com/reviews/petzl_myoxp.htm

Doug

DougPaul said:

BTW, this headlamp can overheat and/or be damaged by lithium batteries (warning from Petzl). (High power LEDs generally include temperature sensors and the circuitry should reduce their power level if they overheat.)

REI listing:
http://www.rei.com/product/721995/petzl-myo-xp-led-headlamp

Detailed review:
http://www.flashlightreviews.com/reviews/petzl_myoxp.htm

Doug

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We have a winner. I've been using lithium batteries on and off for the last few years on these. Lithium batteries were sitting in BOTH of these headlamps for the last six months. The turn on/shut off happened with those lithium batteries, and then with brand new alkaline batteries afterwards.

Should lithium batteries not be used with any LED devices??? I just read a few articles and it suggested that lithium batteries shorten the life of headlamp LED bulbs. Maybe it's best to avoid using lithium batteries completely with headlamps?

Thanks for the help!

Something's wrong. I have never had or seen a problem with Petzl headlamps. If you were using litiums that might be the problem. Petzl headlamps were not lithium compatible until; a year or two ago. Check to make sure you have the Myo2. Any model without the 2 ought not to be used with lithium batteries.

I hope this helps.

Doug

roadtripper said:

We have a winner. I've been using lithium batteries on and off for the last few years on these. Lithium batteries were sitting in BOTH of these headlamps for the last six months. The turn on/shut off happened with those lithium batteries, and then with brand new alkaline batteries afterwards.

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My guess is that the damage occurred in use with lithium batteries, not in storage. New lithiums can put out 1.8V which is too much for some devices. (In contrast alkalines put out 1.55V and NiMH/NiCad 1.35-1.40V when fresh.) The voltage drop under load (the technical term is "internal resistance") is also less than that for alkalines and NiMHs. (NiCads also have a very low internal resistance but, of course, start with a lower maximum voltage.)

See http://data.energizer.com/PDFs/l91.pdf for some discharge curves. (Top of pg 2.)

I'd have to make measurements (current, etc) on undamaged and damaged headlamps to narrow down the nature of the damage.

Should lithium batteries not be used with any LED devices??? I just read a few articles and it suggested that lithium batteries shorten the life of headlamp LED bulbs. Maybe it's best to avoid using lithium batteries completely with headlamps?

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This problem is individual device model dependent. (Petzel issued a warning for a number of its headlamps. http://www.petzl.com/en/outdoor/news/products-news-0/2009/03/17/lithium-battery-information REI repeated the warning on its web pages.) Presumably it is a risk for any electronic device designed before (or ignoring the use of) lithium batteries. I've seen it/heard of it for certain cameras, headlamps, and GPSes. Many of the more recently designed devices are fine with them.

The (REI web page) description of the Myo RXP specifically states that it can be used with lithium batteries.

There is a workaround--run the lithium battery down a bit (in a tolerant device) before using it in a sensitive device. However, this reduces the useable capacity of the battery in the sensitive device. (I'd use a voltmeter before and after the pre-discharge verify that the initial voltage peak had been removed.)

For devices produced since lithiums became popular, you have to read the spec sheets or fine print. A web search may also bring up reports of damage (particularly for devices designed before lithums became popular).

Lithium batteries can also shorten the lifetime of incandescent bulbs.

Doug

FWIW - I noticed that the Home Depot in Hooksett has a display with a package of 2 LED headlamps for $4. They have 2 LED's each, and use a single AA battery. Will probably carry one as a 'give-away spare'.

Kevin Rooney said:

FWIW - I noticed that the Home Depot in Hooksett has a display with a package of 2 LED headlamps for $4. They have 2 LED's each, and use a single AA battery. Will probably carry one as a 'give-away spare'.

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The efficiency of LEDs varies over a wide range. Cheap lights may use poorer quality (ie dimmer) LEDs than the brand name lights. Spare or give-away may be the best service for such lights.

Specific instance: LL Bean has some house-brand headlamps that are clearly rebranded Princeton-Tec units. A side-by-side comparison shows them to be much dimmer.

Doug

Ya'll got me very worried; however, the Black Diamond Zenix IQ, which I know a bunch of people have, specifically allows lithium battery use.

As a side note, lithiums are okay in a SteriPen, though alkalines and NiCad are not.

Any '2' following the model name on Petzl headlamps are lithium compatible. Being a Canuck I want maximum winter performance (before, I used remote battery Petzl headlamps that permitted me to keep the battery pack under a layer or two) from my gear. I know, I know, you guys get winter too, but it'a mentality thing. Check the name; even if it was purchased relatively recently, it migh be from older stock. I now use the Tikka2 and am very happy with it.

BTW, I have seen Princeton Tech headlamps become impossible to turn on or off in severe cold. I think the housing warped.

Your MYO XP should read MYO XP2.

Hope this helps.

Gremlin said:

BTW, I have seen Princeton Tech headlamps become impossible to turn on or off in severe cold. I think the housing warped.

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Which model?

FWIW, Princeton Tec, Black Diamond, Mammut, and Petzl all use plastic housings on their headlamps. Most use single button control. It wouldn't surprise me if the same electronics is used by more than one manufacturer. (Electronics can malfunction in the cold too.)

Doug