The critical considerations in selecting the right battery are:

• Rechargeable or non-rechargeable?
• Nominal, minimum and maximum voltage?
• Initial, average, and maximum discharge current?
• Continuous or intermittent operation?
• If intermittent, the amplitude and duration of minimum and peak current drains?
• Required service life?
• Operating-temperature range?
• A worst-case analysis, including highest expected current at lowest expected temperature and permitted Voltage-rise time to minimum voltage?
• Storage duration and condition?

Battery Chemistries to Consider:

Lithium Ion (Li-Ion) & Lithium Polymer: May have twice the energy density of NiCd, can be capable of high discharge currents, and relatively low self-discharge. Often used for medical, military, industrial, consumer electronics.

Lithium Iron Phosphate (LiFePO4): superior thermal and chemical stability, can handle higher temperatures without significant damage, higher rate discharge, longer cycle life, but lower voltage and energy density than other Li-ion chemistries. Often used for electronic vehicles, power tools, medical and military applications.

Nickel Cadmium (NiCd): fast charge, can take a charge at lower temperature, capable of thousands of cycles, competitively priced, limited size since they have been banned in some regions due to environmental concerns. Often used in medical and industrial equipment, test and measurement instruments, and other applications.

Nickel Metal Hydride (NiMH): No recycling issues, more capacity and no memory effect as NiCd, competitively priced, but can lose charge faster than NiCd. They are often used for small, lightweight, portable, and handheld battery packs.

Sealed Lead Acid (SLA):  Low initial cost, easy maintenance, low energy density, good charge retention, predictable discharge. Often used for medical devices, uninterruptable power supplies, and emergency lighting.

Lithium Primary: Non–Rechargeable: Highest energy unit per weight, mostly limited for low drain applications, can operate in a wide temperature range. Often used for photographic and electronic applications, security transmitters, smoke alarms, communications equipment, utility meters, scientific instruments, and other applications.

Alkaline: Non–Rechargeable: Better performance at low temperatures than Carbon Zinc/Zinc Chloride, low cost, longer shelf life and leakage resistance than carbon zinc. Often used for toys, flashlights and radios.

Carbon Zinc/Zinc Chloride: Non–Rechargeable: Low cost, limited shelf life, susceptible to leakage. Often used in radios, toys, and flashlights.

Silver Oxide: Non–Rechargeable: Small size, stable discharge voltage, good shelf life, able to operate over a wide temperature range. Often used for calculators and watches.

Zinc-Air: Non–Rechargeable: Small size, large capacity, quick start-up, stable voltage, light weight. Often used for pagers, hearing aids, and other small medical equipment.