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Long-life batteries for sound level meters
Technical Note Long-Life Batteries for Sound Level Meters The use of rechargeable, nickel-cadmium batteries instead of the throw-away type is suggested for sound level meters. The advantages are saving of money, and greater convenience in the use of sound level meters on site visits. A simple method for recharging the batteries is discussed, which should be of interest to engineers and public health inspectors, as well as acoustic specialists.
When a sound level meter is in constant use on site surveys, a practical difficulty arises when the batteries run down. One significant feature of the new impulse-type instrument is its increased battery consumption. Indeed, after continuous use for one hour, its three Leclanch~ batteries are exhausted. Throw-away mercury batteries would last twenty times as long, but would cost twenty times as much. We decided to try three rechargeable, nickel-cadmium batteries, and to use a Nagra constant current charger with a 5 ohm, 6 watt resistor in series for recharging. The period for charging was sixteen hours; the sound level meter could then be used continuously for ten hours. Alternatively, the batteries may be recharged from any constant current source in a laboratory. The total cost o f batteries plus accessories was around £6.5. On each chargedischarge cycle, the batteries would replace many Leclanch6 throw-away cells, with a saving of around £1.5. After about fifty hours use of the sound level meter with these batteries, we will have broken even on cost, and gained greatly in the convenience in use of the sound level meter.
ACKNOWLEDGEMENT
This note was prepared as part of the research programme for the Science Research Council Grant B/SR/7775, 'Measurements of Noise in Air Conditioned Offices'. B. HAY D. G. SHAPLAND
Polytechnic of the South Bank London, SE 1 (Great Britain)
Received: 20 August, 1970
71 Applied Acoustics (4) (1971)----O Elsevier Publishing Company Ltd, England--Printed in Great Britain
When a sound level meter is in constant use on site surveys, a practical difficulty arises when the batteries run down. One significant feature of the new impulse-type instrument is its increased battery consumption. Indeed, after continuous use for one hour, its three Leclanch~ batteries are exhausted. Throw-away mercury batteries would last twenty times as long, but would cost twenty times as much. We decided to try three rechargeable, nickel-cadmium batteries, and to use a Nagra constant current charger with a 5 ohm, 6 watt resistor in series for recharging. The period for charging was sixteen hours; the sound level meter could then be used continuously for ten hours. Alternatively, the batteries may be recharged from any constant current source in a laboratory. The total cost o f batteries plus accessories was around £6.5. On each chargedischarge cycle, the batteries would replace many Leclanch6 throw-away cells, with a saving of around £1.5. After about fifty hours use of the sound level meter with these batteries, we will have broken even on cost, and gained greatly in the convenience in use of the sound level meter.
ACKNOWLEDGEMENT
This note was prepared as part of the research programme for the Science Research Council Grant B/SR/7775, 'Measurements of Noise in Air Conditioned Offices'. B. HAY D. G. SHAPLAND
Polytechnic of the South Bank London, SE 1 (Great Britain)
Received: 20 August, 1970
71 Applied Acoustics (4) (1971)----O Elsevier Publishing Company Ltd, England--Printed in Great Britain