I orignally posted this in the fettling thread, but I've referenced it a few times now, so it probably ought to go somewhere more findable.
Back story: The Ixon IQ is an excellent battery light, let down by a couple of major design flaws: Firstly, the plastic catch that holds it shut is a bit flimsy, and secondly that the battery connection depends on no less than 12 spring steel contacts. These have a habit of corroding or lacking sufficient springiness, leading to poor performance or intermittent failure.
Repeated re-bending of the rear contacts to achieve a reliable connection caused mine to fatigue and shear off. I was able to fabricate a replacement contact using a dremel and an old cake tin, but this was fiddly and nowhere near springy enough. It worked like this for almost a year, with me charging the batteries in situ to avoid upsetting the delicate arrangement, but eventually failed.
IxonIQ, which appeared to have battery dodginess.
Charged the cells properly in a individual-channel charger, but the cake tin battery contacts were playing silly buggers when I replaced them in the light.
Got pissed off.
Pressed the pin out of the battery compartment hinge using a vice, a small Allen key, strategically placed fingers and some foul language.
Prised the cover off the compartment containing the electronics (it's secured by a tab on either side, and can safely be attacked with a flathead screwdriver). Noted yet another set of spring contacts between the battery clips and PCB (making a total of 12 spring connections to go wrong). Soldered wires direct to the PCB in the appropriate places and applied some volts. And there was light.
On the basis that I'm much happier wielding a soldering iron than I am attempting to molish intricate shapes out of spring steel, I decided to tape the AA cells together, solder the terminals in the appropriate places, and violently strip out all the superfluous gubbins from the battery compartment. Had a minor "Electron Band Structure In Germanium, My Ass" moment attempting to solder to the terminals of AA cells. Cranked soldering iron up past "Ow! Fucking bastard!", "Will solder high-current spade connectors", "What's that smell?" and "You didn't need insulation anyway" to "Fires of Hades" and completed the job. Discovered that, astoundingly, this battery pack will fit securely within the compartment, so no need for plan B (which involved Tamiya connectors and a drill). Successfully replaced the hinge pin using the corner of the desk and more foul language.
I now have a reliable light with a non-field-replacable battery, rather than an unreliable light with a non-field-replacable-if-you-want-it-to-work battery.
I intend to connect a remote switch to the Ixon for use as a 'dippable' main beam on the recumbent, so will come back and post better photos of the innards at some point.
Until then, I hope this is of use to those wishing to fettle their Ixon. The tricky bit is getting the hinge open: use a ~2mm allen key or similar piece of rod in a vice, and press it out. Pay attention to the pin having a wider head on one side - so it will only press out from one direction. The curvature of the light makes this fiddly and annoying, but rest assured that it is possible.
Refitting is, unusually, a *lot* easier than removal.