Reading through the tonnes of literature I receive on electronics each month does sometimes come up with rewards. Recently I came across news of highly integrated RF circuits for GPS (Global Positioning by Satellite). This will encourage developments in handheld personnel navigators at reasonable prices.

Perhaps of more interest to the average caver are the advances in battery technology that have been announced. VARTA has a new range of portable nickel metal hydride (Ni-MH) rechargeable batteries. These batteries use fewer unpleasant elements but provide 50% more energy density than NiCad cells. They can be trickle charged and have integral protection against overcharge and overdischarge.

If you think that's good, then the batteries just developed by Enegytec will really impress you. They are called Lithium Ion, deliver 3.6 volts per cell, and can support heavy discharge currents. The higher the voltage of your lighting system, the more light you get for less power due to the increased efficiency of the system. The really impressive bit is that the energy storage density is said to be at_least_3__times that of a NiCad! They probably could be charged and discharged 1200 times with only 12% self discharge, half that of a NiCad battery. Also, unlike LiCad batteries, the Lithium Ion batteries do not exhibit a memory effect (the reason why you should completely discharge your NiCad battery before charging rather than the 'top it up' method many people fall into. The more times you top your battery up, the greater the chance that it will only give back a little more than the amount of charge used to top it up). The expected initial price of the new battery is expected to be about 30% more than a NiCad. However, these batteries have been developed for Camcorders and for electrical cars, so it remains to be seen if a battery format suitable for a caving lamp becomes available in the future.