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Temperature is a very important factor in battery as well as battery charger performance. First you need to understand how temperature affects battery operation. Only then will you be able to appreciate the need to control it.
Effects of Temperature on Battery
The ideal battery operation temperature is between 18 to 25 ◦C. As the temperature increases, chemical reactions inside the battery become faster. To a certain extent, this is good since the battery’s output improves. But if the reactions become too fast, the battery chemicals (electrolyte as well as electrodes) may be lost forever, decreasing battery cycle life. At even higher temperatures, thermal runaway becomes a real threat and your battery life is at severe risk.
At lower temperatures, the internal resistance of the battery increases, and hence the output of the battery decreases. At even lower temperatures, the electrolyte might freeze and the battery can stop working.
Effect of Temperature on the Battery Charger
Amount of charging received by the battery depends on temperature too. Charging a battery at normal temperature increases cycle life of the battery. At higher temperatures, battery accepts charge more readily. At lower temperatures, the battery accepts less current. To take care of this, some battery chargers are fitted with temperature sensors to measure temperature when required. Read more about: charging in high and low temperatures.
Need for Temperature Sensor in a Battery Charger
You know from previous posts that when a battery charges, heat is generated. This augments the environmental as well as internal heat already affecting the battery. When the battery temperature is high, the battery charger decreases its voltage supply to enable optimum charging. This prevents overheating of the battery. At lower temperatures, the battery charger applies higher voltage to the battery to counter the increased resistance due to low temperature.
The temperature sensor enables the battery charger to charge at required voltage. This increases battery performance as well as cycle life.
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