Batteries come in a lot of different shapes and sizes. Coin cells and 1/2AA or AA cylindrical batteries are the most popular. However, rectangular and full custom shapes can be better choices for implantable medical devices. Coin cells are normally the least expensive but also have the lowest peak current capabilities. Cylindrical lithium batteries can be constructed in a bobbin technology or spiral wrapped. The spiral wrapped cells have a high peak discharge capability that transmitters often require. If lower cost is the primary objective, then bobbin wound or coin cells may be necessary to meet the cost target. Low leakage capacitors can be connected in parallel with the battery to provide the needed peak transmit currents. Some lithium batteries have a ferrous case. This can be important if any kind of magnetic sensing is needed. If charging is permissible, then lithium ion cells are typically used. Battery charging voltages must be precisely controlled according to the manufacturer’s specification to avoid over charging and damaging the cells.

We have over 25 years experience working with battery operated RFID tags and wireless sensors. Contact Matrix Product Development at www.matrixpd.com or www.RFIDhut.com