UKC

Inspired by all the other threads, I bring you another headtorches thread...

Just wondering if anyone else has had as bad an experience with Petzl headtorches as I have in cold conditions (mainly skiing home after climbing in the Alps)

A few years ago I bought a pair of Tikka RXPs and was surprised to find that within about 30 seconds of trying to ski down a glacier, both torches would totally pack up and remain packed up down to the valley. I put it down to the fact that that they didn't think to install a lock on that model so they were forever turning on in my bag, presumably wrecking the battery.

At the start of last winter I bought a fancy new Swift, only to find it was exactly the same - 90 quid down the tubes then.

I've bought a Nitecore HC68 to try this winter and will report back if it works, would be interested to hear if anyone has managed to use a rechargeable torch for more than 5 minutes in reasonable cold with a windchill  - ie, is it a lithium problem or a problem with Petzl's design?

Also a bit of a warning - so far as I can tell you can't trust a rechargeable Petzl torch to get you off a glacier in winter, even if you have 3!

In reply to Tim Bevan:

Batteries dying rapidly in the cold is a well known issue, but 30 seconds seems incredibly quick.

In reply to Tim Bevan:

Its a chemistry issue, lithium ion won't work well below about -10. You can either get a torch with a battery pack on a lead that you can keep inside your jacket, or use batteries with a different chemistry. Non-rechargable lithium AAAs should work down to -40, or you could try getting one of the low-temperature 18650 li-ion batteries to go with your nitecore. I've no personal experience with them though, because they're expensive and its rare that I'd need it.

In reply to Tim Bevan: at some point put them in an inside pocket.  Mine seem to do ok

In reply to Tim Bevan:

Really happy with my 1987 Petzl Zoom as it is TOTALLY dependable in all weathers and has batteries that last forever since I constructed some home made LED lightbulbs for it that work far better, give better light than the original incandescents.  Bombproof at the expense of being a bit more bulky.  I have a modern LED torch by BD but the Zoom adaptation beats it for reliability and weatherproofing and battery life.

Of course it does not flash or have variable light level or red light for reading.

In reply to wbo2:

Are yours rechargeable jobs? I keep them in a pocket close to my body all day, and even tried rotating them in/out of a pocket as they die, still no joy and very frustrating! 

In reply to Tim Bevan: Some are.  I don't have the Petzl rechargables, just AA and AAA

Having said that I have a Silva with a built in rechargable, and that does OK.  I don't do complicated headtorches - I keep it pretty simple.

This is my favourite https://silvasweden.com/collections/running/products/tail-runner

In reply to wercat:

Can you still get those funny batteries for them?

In reply to Tim Bevan: Petzl Pixa with non rechargeable lithiums have never let me down to about -30. I’ve never used the rechargeable model. 

In reply to Tim Bevan:

I've had a Petzl Actik Core for 4 years now, used in very cold conditions in Norway and on Winter ML training all week, plus countless other winter mountain days, and I've never had an issue with it. It's re-chargeable but also takes AAA batteries. I've never had to use AAA batteries in it though, the rechargeable battery has been faultless.

In reply to TobyA:

There was an AA cell adaptor available.  These days with an LED bulb (I put resistors in mine, made from a broken bulb, so it would run with the current limited  below the 1W rating of the LED element) you could make use a single cell rechargeable Lipo battery but as it happens I have a very large stock of slightly out of date original alkaline batteries

giving them a slight top up trickle charge before they are used has proved effective to vastly prolong the original storage life and they cost me next to nothing to buy.  I've used hardly any of them as the batteries seem to last forever.

In reply to Tim Bevan:

I've had a a Tikka RXP for years. Used it on loads of alpine adventures down to - 15/20c. Was always nervous using it on multi-day trips and used to take a spare torch, still do when it really matters but I've been quite impressed with the battery. 

Never noticed any difference with temp, so not sure what's going on with yours. 

In reply to Tim Bevan:

I've one of the nao torches and can't say I've had any issue, we also use petzl torches in our MR team and the perform well.  

How long are the actually lasting, guessing 30s is an exaggeration.  Most modern petzls go into a "limp home" mode once batteries deplete which usually gives usable light (ie you can see your feet) for a few hrs so completely shutdown sounds like something off is going on!

I'm surprised you got the same issue with 2 models - any chance it is user error / accidental switch on?

Worh giving petzl a shout and seeing if they can advise maybe.  I've normally had good service from them when I called up and spoke to someone.

Cheers!

Stu

In reply to Tim Bevan:

I’ve used a Fenix with a 18650 battery down to about -35C running and also night ice climbing down to -20 ish with no issues (the climbing sessions were about 4 hours long on a high brightness setting). I think the Nao also takes the same battery. Although in these cases the lamp has been kept warm up to the point it was used. 

In reply to Tim Bevan:

Used a rechargeable petzl on the Eiger in January. Minus 19C. No issues climbing or at bivvy 

Super interesting to hear people using them no bother, I wonder if its the additional wind chill of skiing that does in for mine (should have said, they work fine in the freezer but not sure how good of a test that is as they actually come out a little warm if you use them on high beam).

In reply to StuDoig:

No significant exaggeration, I've obviously not timed it but almost as soon as you start skiing, they're off. Done the VB several times without a light as a result. You're right about the limp home light actually, good luck using it for any more than tying your laces though!

No chance they were on in a bag before hand since I've started keeping the batteries separate to the torches (in my pocket for warmth).

I did actually email Petzl and while they were nice and friendly, they basically just said it sounded unusual and if I wanted I could send them back for them to have a look at. When pressed on what they'd do they said put them in a freezer, which I'd already tried and found that they worked fine in there (even straight after having died skiing, having warmed up in the house first of course). I really didn't think they'd find much of interest so didn't bother, especially since I was away at the time. Maybe I should send them off now...

In reply to Tim Bevan:

Haha, aye I'd hate to be anywhere steep in emergency mode!

Worth firing them back to petzl I'd say - if the are working in the freezer, it doesn't suggest cold is the issue - it'd be interesting to see if the come up with a fault!  

Worst case I suspect will be mystery fault and your torches back,  best case identified fault and new torches!

Cheers,

Stu

In reply to Tim Bevan:

Windchill doesn't lower the actual temperature! 

In reply to TobyA:

But does increase the rate of heat loss from the torch, potentially pinning it at whatever the air temperature is rather then warming itself up a bit as it works.

In reply to norrisdan71:

Like norrisdan71 says this is all about the batteries not petzl. Very roughly speaking you have 4 types of battery. All of them are affected by cold and perform worse than at room temperature.

Lithium ion, these are not good in very cold conditions. These are usually 3.6v (nominal) rechargeable. Examples include 18650 batteries and petzl core.

Standard rechargeable 1.2v (nominal) usually NiMH. Examples often in  AA, AAA format etc. Suffer badly from the cold.

Alkaline batteries 1.5v (nominal) and zinc carbon, these are OK ish and better than Li Ion, but not great in extreme cold

Lithium (Lithium iron disulphide) 1.6v (nominal) examples include Energizer ultimate lithium commonly in AA and AAA format. These cope with cold much better than other choices. Expensive but invaluable if you know it's going to be very cold. Not rechargeable

Pick the right battery, if your headtorch can use AA or AAA consider using Energizer ultimate lithium if you know it's going to be very cold. But if it isn't cold probably avoid them as they are expensive and not rechargeable. (Double check which battery types is supported for your torch) 

In reply to David Coley:

I remember you posting in advance of that trip. How did it go?

In reply to Tim Bevan:

As the battery is inside a windproof plastic box I can't imagine it impacts on the battery at all. High powered LEDs are designed to allow heat to not build up (MTB lights for example) but this doesn't appear to factor into headtorch design so I can't imagine they are putting out any noticeable amounts of heat, and surely that's all inside the casing anyway so windchill would have very little impact. 

BTW, I've used various non rechargeable headtorches in Finnish winter conditions for years - with normal alkaline batteries I never noticed any big problems, same for bike lights. By the time I moved away I only had recently got Chinese LED torches with 18650 rechargeable batteries for bike lights and they worked fine through winter.

In reply to TobyA:

Not sure I agree with this, the Petzls I own have cooling fins hidden in a little wind tunnel type feature between the leds and the battery, presumably designed to keep the leds cool but also (not sure if deliberately or not) stop the leds warming the battery. Maybe good in hot places in summer but not so good for my use case.

Also, if you put a Swift into the freezer on a high beam for half an hour it'll come out noticeably warm, so they must be producing some significant heat. 

This is what's giving me hope for the nitecore - the battery is integrated very tightly with the leds in a metal case - it gets pretty warm on high output even with a bit of airflow. Remains to be seen if it's enough to let it work out skiing though!

In reply to TobyA:

Wind chill can have no effect on the battery - it's really a 'human factor' thing. The only relevant matter is the ambient temperature. Whether or not that's associated with either no wind, or a 100 mph wind, won't make any difference.

In reply to CantClimbTom:

I wonder if wearing an extra hat layer/hood over the head torch helps.  Plastic is a better insulator than metal but heat loss is certainly a problem.

The technical solution military radios used in very cold conditions (batteries in metal cased radios would certainly have been wind chilled) for decades was to allow connection of the (sometimes very large) battery via an extension lead so that the battery could be kept warmer under the operator's clothing closer to the body and away from weather, irrespective of any discomfort to the operator!

What about a Headtorch Cosy as a product idea for extreme conditions?

In reply to Rob Parsons:

Again I don't think this is right - surely 'wind chill' is just what we call forced convection in the context of a human, and if there's wind then the heat loss from any object will be greater than without: https://en.wikipedia.org/wiki/Forced_convection

Think about an old aircooled engine - when you're stuck in a traffic jam not moving it'll overheat, even though it's fine on the open road. The air temp is the same in both cases, the only difference is the "wind chill" it experiences. 

In reply to Rob Parsons:

Again I don't think this is right - surely 'wind chill' is just what we call forced convection in the context of a human. Heat will always transfer faster in the presence of some wind: https://en.wikipedia.org/wiki/Forced_convection

Think about an old aircooled engine - it'll overheat when sat in traffic, even though it's fine on the open road when working harder. The air temp is the same, the only difference is the "wind chill" (forced convection) it's experiencing when moving.  

In reply to Tim Bevan:

Yes, I agree with that. So my previous comment was out of place.

One thing for sure though, is that, irrespective of wind speed, the batteries can only get as cold as the ambient temperature. So an experiment for someone to do would be to:

1) measure the ambient temperature when you're out at night; then,

2) chill the batteries to exactly that same temperature in a freezer, and see if the headtorch then works or not.

In reply to Tim Bevan:

Have you tried putting an electric fan in your freezer with the headtorch to create a "windchill".

In reply to wercat:

There have been some torches with a battery pack on a long wire and pouch/strap to be worn inside a jacket, I think Petzl made a version of the Zoom like that back in the day for extreme cold.

Or, if you want to see a shockingly poor quality bodge, take a look at the attached pic, it a bit of wood and screws washers with wire soldered to it to make a fake-battery. Not pretty but it works if you want to externalise power (or charge battery packs that don't fit in ordinary chargers)

In reply to CantClimbTom:

To add to this, there are also some Li-ion rechargeable batteries designed for cold temperatures. I'm not sure on the technical details but I guess they have some additive that makes them less prone to freezing. You can get 18650 batteries that give quoted working temperatures down to -45, but they cost £30 each rather than £5.

Important to note as well, particularly for winter campers, that you shouldn't ever try to charge lithium batteries below about -5 - when they're partially frozen bubbles can form and they can catch fire or blow up.

In reply to CantClimbTom:

Excellent!

A really good electrical insulating material for improving such bodges is the plastic of which milk bottles are made.  I've found countless uses for these in electronics/electrical applications.  you can make a multi cell pack by rolling tubes of the milk bottle plastic for each cell and then taping them together insulated from each other.  Insulating tape is handy to hold it all together.

In reply to nxnxnx: 'the batteries can only get as cold as the ambient temperature.'  I don't think so - else air cooling has no value

In reply to wbo2:

There is the ambient temperature and there are sometimes flows of incoming colder air.  You can trace these in the Lake District by the pattern of very localised frost/snowfall where summits quite close to each other can be clear or snowed/frosted.

In reply to wbo2:

I think you have a misconception about air cooling. It cannot reduce the temperature of anything below the temperature of the air being used (i.e. the ambient temperature.)

In reply to Rob Parsons:

Believe me, I'm a founder member of the "when people talk about windchill they're invariably talking bollocks" club! But I think Tim's point is true, but I suspect to an unimportant degree. Wind will lead to things cooling down to the ambient temperature faster. Of course it can't cool them below the ambient temperature. But that's not taking into account any entity that is producing heat, a human body or an LED. That body will lose the heat it is producing quicker with cold air moving over it than in still air. So if the LED heats the battery to any degree, windchill could be a factor - but modern LED seem to produce so little heat, they're so efficient at making only light energy I doubt it's a real issue. 

Some engineer or physicist can check my working out on that but I think my logic is sound! :⁠-⁠)

In reply to TobyA:

I think this is true for low output torches, but the ones I use for mountainbiking get roasting, and the ones I'd like to use for skiing do warm up significantly. Source - I own them, have tested it and am an engineer

In reply to wercat:

This is a great plan! And much easier than my original idea of making my own torch!

In reply to Tim Bevan:

Don't know about the cold – I do know that that's a standard worry with Lithium-ion battery technology in general – but, honestly, I'd seriously question a purchasing decision for a Petzl head-torch after what I've found with my most recently bought one.

Following the advice that "the best place to store spare head-torch batteries is in a spare head-torch" -- something I long subscribed to -- I bought some super-light Petzl jobbie (not sure what it's called - has strings instead of a strap and is USB re-chargeable) to live in my pack as an emergency light. It's there whether I'm carrying my "real" one (an ancient verson of the Petzl Nao product line) or whether I'm not expecting darkness at all. It is simply ever-present whether I'm hiking, skiing, climbing or just walking far enough to get to a lakeside picnic spot that's sufficiently distanced from the main lawn that some "FKK" swimming won't ruin anyone's view.

Problem is though: IT TURNS ITSELF ON IN MY BACK-PACK!

I mean, seriously? Of ALL the possible design flaws in a head-torch, surely this one must be the most "newbie" of "newbie" errors, ever? How can a serious head-torch brand like Petzl allow such a poor design to pass QA? It absolutely fathoms me!

Anyway. After seeing that they let that out, I'm pretty sure I'll be researching alternative brands when next I need to replace either my primary or my backup.

In reply to Xharlie:

That sounds a lot like the Petzl Bindi

Did you know it has two lockouts? One electronic, hold the switch down for about 5 seconds. Then apply the mechanical one which is to rotate the light in the bracket/casing. There's a position that it ever so slightly clicks into, which protects the switch from being pressed as it's blocked by the bracket/casing

I carry mine all the time in my bag as a spare, usually for biking, and it's never come on. 

Apologies if I've got that wrong!

In reply to CantClimbTom:

I bodged  one for my zoom, back in the day and it worked well XC skiing at -40 in an Alaskan winter.

In reply to Tim Bevan:

On my last expedition I brought 2 main torches; a Black Diamond Polar Icon with a remote battery pack, and my simple Petzl Actik Core.  At night it dropped down to -40 deg C (without windchill) and I was solo in the tent... so cold!  Cold enough that one morning even my GPSMAP 66i (often used in Antarctica) refused to switch on and then, when it eventually did, gave dire warnings about the temp being too low (none of my other electronics worked).

I assumed that the Actik would be terrible and I'd mostly use the Polar (with lithium batteries).  The results REALLY surprised me... the Polar Icon died within minutes and the Actik lasted for hours on low/medium!

For my next Arctic expedition I'm bringing 2x Actik Cores and leaving the Polar remote battery headtorch behind.

In reply to Rob Parsons:

evaporative cooling?

In reply to magma:

I'd worry if your torch can do this

In reply to crayefish:

i can imagine fading battery heat causing condensation and runaway evap cooling if you're not careful

In reply to Tim Bevan:

Agree with this. Efficient as they are, LEDs still waste >50% of their input power as heat, so a really powerful torch with eg a 1000lumen LED will draw 4-6W or so, and dissipate a few W of heat in the LED. Additionally some power will be dissipated in the driver circuit and the internal resistance of the battery. The power dissipated in the LED is easily enough to destroy it if not effectively removed. Plus LEDs improve their efficiency as their temperature is reduced so cooling them is important.

This is of course a vast improvement on an incandescent lamp where pretty much all the power into them is lost as heat and the actual light output is almost a rounding error.

In reply to richard_hopkins:

Hi Richard

Can you advise with my Fenix HM65r please.

Its new and has had 3 charges with the battery supplied.

Charged it fully last night so that all 4 lights were lit not flashing.

Used it for 20 mins tonight at 100 lumens at 12 degrees temp. Very nice and bright.

Got to the car and only two of the 4 lights were  lit.

Put it on charge and it’s charging up from two lights full with third and fourth light flashing.

Is this normal for it to drop so much charge or is it a torch or battery fault.

The metal housing was cold after use.

Thanks

Dave

In reply to Dave the Rave:

Do you have another 18650 battery to try with it? If not could you borrow one from someone with a Vape to try out?

I doubt the number of lights showing the charge state is particularly scientific, but it should be able to power the light in 100 lumen mode for many hours, so showing measurable depletion in 20 minutes seems very suspicious.

If you turn up the power to 1000 lumen, how long does it stay lit for? I looked up that torch and it says it should last 4 hours - does it? I didn't find 100 lumen you mentioned in the list of options but it says 130 lumen should last something like 50 hours, so the first paragraph seems doubly fishy! 

Maybe your battery (or charger) is faulty somehow.

In reply to richard_hopkins:

Thanks Richard

About to buy one

i agree

I’ve read a bit about it and the tables supplied aren’t too realistic. The times on the box are at a higher ambient temp and it doesn’t state that you will get 1000 lumen for 4 hours, just light as it drops to the lower lumen pretty quickly.

Charger is the mains, battery change is my first port of call.

Will definetly be taking a spare battery and back up torch until I can trust it.

Thanks a lot

Dave