Defibrillator batteries are typically designed to reliably generate power for use in emergency situations and life-saving equipment. Defibrillator types vary from internal implants to user-friendly automated external defibrillators (AED) and specialist hospital and emergency responder equipment. The batteries designed to accommodate this wide range of equipment run the gamut of typical battery technology, from household alkaline batteries for training equipment to proprietary batteries designed for brand specific equipment. Battery types can include traditional lead acid types, nickel cadmium (Ni-Cad) or nickel metal hydride (NiMH), lithium-ion (Li-Ion), gel cells, and absorbed glass mat (AGM) varieties.
Typically designed for long life and reliability, defibrillator batteries are usually designed to wear out gradually over four or five years. An internal cardioverter defibrillator (ICD) is implanted surgically into a patient to monitor heartbeat and administer small electric charge when it detects an irregular heartbeat. ICD defibrillator batteries are implanted surgically and subject to high-voltage electronic or magnetic interferences. AED defibrillators rely on battery power supplied by larger external batteries that may also power equipment monitors, and may be rechargeable. The battery generates a charge that travels through pads placed on a person's chest; this is to restore regular heartbeat during cardiac arrest and restore function of the heart.
Lead acid defibrillator batteries consist of two types: the flooded, or wet cell, and sealed lead. This proven technology offers a lot of industrial support and product compatibility, though this type presents acid and gas hazards. AGM defibrillator batteries fall into the sealed lead type; like gel cells, they are non-spillable and usually designed to deliver a high charge when demanded. Gel cells, by comparison also offer good performance with a slow discharge rate, but with higher costs and higher sensitivity to improper recharging.
Ni-Cad types are cheaply produced, popular batteries that hold their charges well, and are often used in emergency equipment. In contrast, NiMH and Li-Ion both possess higher energy density and higher costs. These three types are all rechargeable. The most powerful, Li-Ion, boasts the highest volume capacity of these varieties, giving them a very long life span and shelf life. Li-Ion batteries are susceptible, however, to impact shocks that might undermine the seal and storage capacity. To compare, equivalent Li-Ion batteries may self-discharge under 5% per month, with NiMH at about 10% and Ni-Cad at about 20%.
Some defibrillator batteries are designed especially for certain purposes, such as for use in aircraft, training, or medical research equipment. They are often left constantly charging or exchanged frequently, with spares and backups available in the event of any problems during an emergency. Awareness of the lifespan, maintenance, and disposal requirements of batteries ensures life-giving medical aid in time-critical emergency responses.