Conversion of mining lamp headsets to operate with helmet mounted Mk1 Petzl Zoom Box & NiMh battery pack
The LEDtechno packs used 7/5 AF 3600 mAh NiMh cells (3s). Rather tricky to get hold of in 1995, but now widely available in capacities around 4500 mAh, and in many applications superceded by higher capacity, lighter weight li-ion cells. They do however have the advantage of being more toleratant to a good soaking than li-ion cells. If you wish to use higher capacity, lighter weight li-ion 18650 cells then a more waterproof battery box is essential; potentially accommodating 2-3 cells parallel wired @ 3.7v, with suitable protection circuitry.
In the UK, ex mining lamps (Oldham, CEAG) have been readily available, and hence widely used by cavers. The appearence of high capacity NiMh cells in the mid 90s (not long before the arrival of white LEDs) initiated a transition from large waist mounted batteries to helmet mounted packs. The favoured method of attaching these interchangeable battery packs was the 'old style' Mk1 Petzl battery box.
Though by no means anywhere near as widely used by cavers today, mining lamp conversions retain a following. A lamp constructed from a surplus Oldham headset, CustomPITLAMP Module, Mk1 Petzl Zoom battery box and 3.6v Nimh cell pack certainly wouldn't be a bad solution. It is worth noting that the Mk1 Zoom box has been discontinued by Petzl, and a new one is difficult to get hold of; the best approach being to buy an orginal Petzl Zoom second hand via ebay.
Consequently, the original LEDtechno (now CustomDUO) 3 cell 3.6 volt NiMh battery (3 series) for Petzl boxes, double heatshrunk with Tamiya II plug, has become very much the standard configuration for helmet mounted mining lamp conversions. These battery packs were significant in the development of the first LED based caving lamps, incorporating LED bulb conversions. Simple by modern standards, these conversions used the first White 5mm Nichia LEDs (also manufactured by LEDtechno in the 90s).
.... or alternatively AA batteries can be used. You can get AA holders, but the battery contacts are often affected from being bashed around etc etc. Heatshrunk battery packs using 3 or 4 good quality AA cells, such as Eneloops have been available from the Component Shop
Nimh battery packs for petzl zoom boxes are now manufactured to the original Ledtechno (Customduo) design by Strikalite Batteries, in 4.0ah and 4.5ah format (Product ID 871 and 872). They also offer suitable battery chargers.