Gone are the days when laptops drive the definition of low-power. Suppliers rely more and more on consultants to provide specific skills needed to design today’s exploding array of battery operated devices including wearable devices, home health, mhealth and implantable devices. The most challenging problem is to support wireless devices with sufficiently long range and small batteries. Batteries often define the size of a device and the length of time between charges. If batteries progressed like electronics, we would have a coin cell that could power a car and cost a penny. This will never happen, because battery technology is limited by the chemical storage of energy.To overcome battery limitations we conserve power by limiting transmission power, shortening transmission and receive time, using low power sensors, and shutting down unneeded electronics. This takes a combination of system design, circuit design, and software to achieve the optimum solution.