Probably few of us have ever had the pleasure of being on an Arctic cruise and having your flashlight or radio suddenly die because the rechargeable battery froze solid.
Well, it’s not like you can’t find sub-freezing temperatures in the northern areas of the US, Canada, EU and Asia. Given plenty of sun, wouldn’t rechargeable batteries be the wise choice instead of carrying a bunch of non-rechargeable batteries? What about as backup power, in case grid power goes out? But then, there’s the freezing problem.
Current nickel-cadmium [NiCd] rechargeable batteries typically freeze at -20°F, making them useless. Panasonic, a global leader in rechargeable battery technology, has developed a new line of NiCd rechargeable batteries that can be used at temperatures as low as -40°F.
In order to overcome the electrolyte freezing problem, Panasonic made improvements across the whole spectrum of NiCd rechargeable battery construction. The negative-electrode was reconfigured on the nanoscale to increase surface area without increasing physical size, while the nickel positive-electrode was strengthened to resist expansion during charging. Overcharging could easily occur at sub-freezing temperatures, so this was an important step.
Finally, the electrolyte needed to be upgraded to resist freezing, which was easily solved by increasing the density to lower the freezing point below probably -50°F. Panasonic expects to market the new Cadnica GT Series NiCad Rechargeable battery, in sizes including SC, C, and D, in the northern areas of Japan and pretty much every region north of the 40th parallel. Capable of charging and discharging at temperatures as low as -40°F, this new battery line will be useful in sub-freezing zones in emergency lighting and backup power for computer equipment and weather monitoring stations.