The so-called miracle battery that merely live in controlled environments is excluded.
We scrutinize the batteries not only in terms of energy density but also longevity, load characteristics, maintenance requirements, self-discharge and operational costs.
All other chemistries prefer a shallow discharge and moderate load currents.
The Ni Cd is a strong and silent worker; hard labor poses no problem.
Lead Acid — most economical for larger power applications where weight is of little concern.
The lead acid battery is the preferred choice for hospital equipment, wheelchairs, emergency lighting and UPS systems.
High durability Ni MH batteries, which endure 1000 discharges, are commonly packaged in bulky cylindrical cells.
The energy density of these cells is a modest 70Wh/kg. Li‑ion packs are being produced for defense applications that far exceed the energy density of the commercial equivalent.The mobile phone industry is an example of clever adaptation.Emphasis is placed on small size, high energy density and low price. The inscription of Ni MH on a battery pack does not automatically guarantee high energy density.Since Ni Cd remains a standard against which other batteries are compared, we evaluate alternative chemistries against this classic battery type.Nickel Cadmium (Ni Cd) — mature and well understood but relatively low in energy density.Lithium Ion Polymer (Li‑ion polymer) — offers the attributes of the Li-ion in ultra-slim geometry and simplified packaging. Figure 1 compares the characteristics of the six most commonly used rechargeable battery systems in terms of energy density, cycle life, exercise requirements and cost.