Page 50 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

3.5 Solar engine flag spinner

is light. For robotics, especially when powering drive motors and
components, we often don’t have this option. In this case one tries
to provide greater battery capacity. 29

Battery voltage

Battery voltage varies throughout the life of a battery. If you mea-
sure the voltage on a fresh D-sized 1.5V alkaline battery, it will
read approximately 1.65 V. As the battery discharges, its voltage
drops. The battery is considered “dead” when the voltage drops to
1.0 V. Typical discharge curves for carbon-zinc, alkaline, and nickel-
cadmium (NiCd) batteries are illustrated in Fig. 3.6.

Notice that a fresh NiCd 1.5V battery actually delivers about
1.35 V. While its initial voltage is lower, its discharge curve is fairly
flat compared to that of carbon-zinc and alkaline batteries deliver-
ing a constant 1.2 V.

Primary batteries
Primary batteries are one-time-use batteries. The batteries we will
look at in this class deliver 1.5 V per cell. They are designed to deliver
their rated electrical capacity and then be discarded. When building
robotic systems, discarding depleted primary batteries can become
expensive. However, one advantage to using primary batteries is that

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