Power considerations
Powering the wearables you make is an important part of the overall circuit. Using a Lithium Polymer (LiPo) battery means that it is rechargeable. We need ones rated at 3.7 V for our projects because the circuit boards we are using are 3.3 V-rated, as shown in Figure 14.22:
Figure 14.22 – Varieties of LiPo batteries
The battery’s capacity is measured in amp hours – you’ll see mAh for milliamp hours on the LiPo batteries that we use for wearables. We can use a capacity in the range of 150 to 2000 mAh for our projects. They will be flat and different rectangular shapes. They typically have a foil-type case and don’t weigh a lot, which makes them good for wearable designs. It can be a good idea to provide information for the wearer to know how much charge is left. You can buy a battery capacity indicator (see Figure 14.23) that you can integrate with your circuit:
Figure 14.23 – A battery capacity...
