NICKEL - CADMIUM FOR ECONOMY

ERIC CLARK. (Area 17)

When I bought my auto-winder a couple of years ago together with IR remote control I was all set for taking wild life shots from a distance. Once started I soon found that the business of leaving gear switched on waiting for the right moment soon soaked up the battery power - a 9 volt PP3 only lasted a day (price about £1) apart from several AA equivalents - both types cover my use for a number of photographic items such as pH meter, Flashgun, Auto-winder etc.. etc. and have quickly paid for the initial outlay.

Cameras, Winders, Motors, Flash equipment, radios, recorders, everything, in a word, that needs electricity to function and usually bears the additional word "portable" in its name gets it`s electricity from batteries. Simple zinc-carbon batteries are often less suitable for this purpose, and the high cost of alkali-manganese batteries are hard on the pocket. Here, the rechargeable nickel-cadmium cells or NiCd cells for short, are an economical long term alternative to the traditional dry-cell battery.

using NiCd cells is especially worth-while with devices that are used frequently or are continuously in operation. Under favourable conditions a NiCd cell can be recharged from 500 up to a 1000 times. It is safe to assume that about two to three charges of these cells correspond to the capacity of one alkali-manganese battery of the same type. This means that in regards to costs, one set of cells (plus a charger, if not yet on hand) is the equivalent of about 300 sets of batteries: clear proof of the shriftness of the NiCd cells.

The cell voltage of the NiCd cells is usually about 1.5 volts. This is, however. no reason for not using them instead of normal batteries, which have 1.5 volts., I refer of course to the AA type. The voltage in a NiCd cell remains very constant over a long period of time, whereas the battery voltage of a normal 1.5 volt type sinks relatively fast. This is why most battery-powered electric devices work perfectly well at 1.2 volts. Due to their voltage constancy, using NiCd cells is technologically more efficient and reliable. NiCd cells are just as trouble-free to handle as conventionable batteries. In the interest of long life, however, care should be taken to avoid frequent over-charging far beyond the fully charged state, to do a 24 hour long term recharging after a long period of un-use or when the cells have gone completely dead, and in general to recharge the cells once the device shows signs of weak running. Often it is worth-while to buy and extra set of cells which can be recharged while,the first pair is in use, this will depend a lot on the amount of usage.

Before using NiCd cells, always check to see if the manufacturers permit their use in their equipment, so always consult the operating instructions. Usually there is a warning if NiCd cells are not suitable to use; otherwise it is safe to do so.

Note Current price in my local shop for NiCd cells is: PP3 equivalent £5.40, AA equivalent, four for £6.00.

Some battery chargers will take a wole range of battery sizes and could be well worth consideration since there is a fairly good range of NiCad's.

The above chart shows the form of carbon-Zink and NiCd cells losing their power during use.

The Carbon-Zinc battery starts at 1.5 volts, falling slightly all the way through use until rapid fall-off at the end of it`s life.

A NiCd cell starts with an initial surge of 1.24 volts when appliance is switched on, then maintains a constant level until just before voltage
drop indicates need to recharge.