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Petzl XP2 head torch / Core rechargable battery

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Kim:



http://www.petzl.com/en/outdoor/headlamps/universal/tikka-xp

You can't really go wrong with Petzl head torches.  There are certainly cheaper options (Alpkit's offering is hard to beat), and others may have the edge on brightness as technology progresses, but they're reliable, well designed and perform well.

I upgraded from a Tikka Plus to an XP2 a couple of years ago, as I found that I wanted a more powerful beam for night riding on a recumbent (where the bike lights are fixed to the frame axis rather than the steering, meaning you can end up turning into darkness on tight corners).

The XP2 does exactly what it says on the tin: two brightness settings, an excellent flip-in diffuser, a red LED that people with functional red vision can use to preserve their night vision[1], and the usual flashing modes.  Compared to the Tikka Plus, the beam is whiter, smoother (when diffused) / sharper (when focussed), and of course brighter.  Mechanical construction is broadly similar, the main difference being that the battery compartment is much less fiddly to open on the XP2.  There's a weight difference, but I'd have to read the specs to tell you what.  Oh, and the strap comes in less tasteful colours, but includes an emergency whistle as part of the plastic buckle.  I haven't tested battery life scientifically, but found I typically used it at full power less often, with a corresponding improvement in battery life.

My main niggle, from a cycling / camping perspective is that the power button operates in the sequence high-low-flash-off (with a long hold to switch between red and white).  After a few seconds, a single press switches it off.  As such, switching from low to high requires that you switch the light off (one press) then back on again (another press), and switching from high to low requires that you switch it off (one press) and then on (another press) and down to low (yet another press).  I'd much prefer an easy toggle for cycling, and for it to come up in low brightness mode first for camping.  As issues go, this is a fairly minor one.

Much more interesting is the Core battery pack...

http://www.petzl.com/en/outdoor/headlamps/core-rechargeable-battery

This has had positive reviews on the web, and given the appeal of avoiding having to deal with odd numbers of AAA cells, I was attracted to the idea.  As luck would have it, I was able to find one cheaply to play with last summer.

The XP2 (and other compatible torches) have a break-and-re-make battery compartment hinge - you simply remove the three AAA cells, twist the two parts of the unit apart, and re-assemble with the Core - which has both male and female hinge/clip parts - in the middle.  This adds significant thickness to the overall unit, but a nett reduction in weight.  As a glasses wearer, I can't complain about moving the light source slightly further out from my face.  It's still easily pocketable (much more so than something with a separate battery pack at the back of the headband).  It also means that it's trivial to remove the Core and revert to using AAA batteries at any time, or even have multiple Core batteries.

Battery capacity is less than with Alkaline or primary lithium cells - probably on a similar level to hybrid (low self-discharge) NiMHs - but this is offset for most practical uses by the simplicity of recharging: you just flip the battery compartment open in the usual way, and plug in a standard MicroUSB power source.  It'll happily charge from your laptop, your phone charger or your USB battery pack thingy.  It doesn't seem particularly fussy about current - if the supply is current limited, it will simply charge at a lower rate, informing you of such with the blinkenlights.  Charge level and recharging status is indicated by three LEDs (the torch's own battery LED is calibrated for AAA cells and should be ignored).

It really does Just Work.  I've been carrying it in my standard bike tool kit and using it for all sorts of things, and really like the way that before something like a night ride you can just plug it in and top it up, without faffing about with cells and chargers.

But the really clever thing is what happens when you plug it into a computer (well, one running Windows or OSX, with their confusingly named "OS" software.  There's not a lot to the OS application, but it's very clear and simple to use.  You program it with the details of your particular battery/torch combination, and it allows you to interactively program the power regulation in the Core battery pack.

By default, the regulator's voltage will discharge in a curve to mimic the behaviour of an alkaline cell, but OS allows you to change this to constant regulation at customisable levels.  So you can say "run at full power until the battery's almost dead" or "run at 5% power until we die of boredom" or anything in between.  The user interface takes the form of sliders on a graph that's calibrated in brightness and runtime - all very shiny and intuitive.  It allows you to program the behaviour of full and low power modes independently, and indeed program 'full power' to be less bright than 'low power', if you so desire.

This is fairly brilliant if you're doing something like a night ride, or running event or whatever, where you know that it's going to last 'n' hours - you can program the regulator to give you exactly the right amount of burn time, so you always have as much light as possible.  It's also quite nice to be able to turn the 'low power' brightness down a bit for reading in your tent.  Last week I attended a film festival, and was able to set it to be *really* dim[2], for reading the programme and rummaging in bags purposes.  It's also worth noting that the Core infers which mode the torch is in by the current drain, so it will power up at full brightness for a second or two before assuming the programmed regulation strategy, which means lowering the programmed output won't avoid accidental fumbly blindings.

Geek note: The Core appears as a USB mouse type device on the bus, so even in the absence of the Petzl application, is minimally confusing to the computer if you plug and unplug it at random:

--- Quote from: Syslog ---Jun  7 02:14:56 penelope kernel: [30104.910159] usb 2-5.3: new full speed USB device using ehci_hcd and address 8
Jun  7 02:14:56 penelope kernel: [30105.033096] input: PETZL CORE USB Rechargeable Battery by PETZL as /devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.3/2-5.3:1.0/input/input6
Jun  7 02:14:56 penelope kernel: [30105.033283] generic-usb 0003:2122:1234.0005: input,hiddev97,hidraw4: USB HID v1.11 Mouse [PETZL CORE USB Rechargeable Battery by PETZL] on usb-0000:00:1d.7-5.3/input0

--- End quote ---
I haven't made a serious attempt to communicate with it in Linux.  I dare say that the right HID incantations could get it to return its battery status and so forth.


So yeah, the Core's programmable regulation is a bit of a gimmick, but a genuinely useful one.  If USB charging appeals, then I highly recommend it.  My only complaint would be the excessively high RRP and the lack of a supplied mains adaptor (they do include a USB cable).

I look forward to the next generation that incorporates this concept.  Programmable button sequences please!


[1] I considered replacing it with a green LED that would be more useful with my vision, but couldn't see how to get the case open non-destructively.
[2] Which is how I felt when I went on to attempt to explore the Netherton Tunnel without remembering to re-program it for full brightness  :facepalm:

andrew_s:
The (earlier) Myo RXP also has programmable brightness levels, with 3 modes each with one of 10 brightness levels. As they can all be set to any level, you can reverse the default bright/medium/dim sequence if you want. There's also a flash mode that can be set to fast, slow or SOS.
Programming is by pressing the buttons with the appropriate long & short presses. Power is 3xAA in a rear compartment, and there's a similar flip-up diffuser. Both minimum and maximum brightness are brighter than the equivalent Tikka XP2 levels, and there's no red led.
One thing it doesn't do, that the earlier non-programmable Myo XP did, is return to "just turned on" mode on a flash of the boost button, so you could adjust brightness without turning it off.

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