With new battery technology tending to focus on secondary, rechargeable batteries, it would be easy to think that primary, non-rechargeable batteries are simply a relic from the past. Nothing could be further from the truth. Primary batteries offer many advantages, including high energy, long storage life and being instantly ready for use when needed. They are the obvious choice where recharging is impractical or impossible, and in low current drain situations they have a long operational life, many times that of the inter-charge time of rechargeable batteries. Some notable uses are for medical pacemakers, tyre pressure gauges and sensors, watches, toys, key fobs, remote controls and hearing-aid batteries. The most commonly used types are alkaline and lithium. They generally offer higher energy levels than their rechargeable counterparts but exhibit a relatively low current flow, so they are used to their best advantage in low current situations or where their use is intermittent. Although they are generally inexpensive, in the long term the use of rechargeable batteries is likely to result in some financial savings. Non-rechargeable batteries are far from being an outdated technology, and carrying a spare set of these guarantees that instant power is always available in a way that a set of rechargeable batteries never can.