Design Decisions: When to Choose an Industrial Battery

Each year, billions of batteries are manufactured for use in consumer devices such as flashlights, cameras, tablet/notebook computers, cell phones, and other handheld devices. Meanwhile, a growing number of wireless devices are being designed for use in remote locations that are often off-the-grid, demanding self-powered solutions for the life of the device, especially in areas where battery replacement or recharging is difficult or impossible. These applications include automated utility meters (AMR/AMI), remote wireless sensors, automotive toll tags, GPS tracking devices, oceanographic instruments, process control systems, and various M2M applications. New applications are also emerging that involve extreme temperatures, such as medical cold chain sensors that must withstand -85C and deep hole drilling sensors that operate at up to 150C.

Primary batteries

Primary (non-rechargeable) lithium and alkaline batteries are utilized in a variety of consumer applications, including flashlights, remote controllers, and toys. Alkaline cells are extremely inexpensive and readily available. However, their limitations include low voltage (1.5V), a high annual self-discharge rate (maximum service to two to three years), a limited temperature range (-0C to 40C), and crimped seals. Alkaline batteries are ideal for consumer handheld devices, but not well suited for powering remote wireless devices for extended periods.

Consumer lithium cells (1.5V or 3V) deliver the quick pulses needed to power a camera flash, but operate within a narrow temperature range (-20C to 60C) and have a high annual self-discharge rate. Consumer cells also have crimped battery seals, which are prone to leakage.

Among primary lithium batteries, the overwhelming preferred solution for long-life remote wireless applications is bobbin-type lithium thionyl chloride (LiSOCL2) chemistry, which features the highest capacity and energy density of any lithium battery. Bobbin-type LiSOCL2 cells deliver very long life due to their low annual self-discharge rate, as well as offer the widest possible operating temperature range, and feature a hermetic glass-to-metal seal to resist leakage.

However, not all bobbin-type LiSOCL2 cells are created equal as lower quality brands can only deliver a 10-year operating life with a self-discharge rate of 2% to 3% per year. A superior-grade bobbin-type LiSOCL2 battery can deliver up to 40 years of operating life with an annual self-discharge rate of just 0.7% per year.

Rechargeable battery differences

Cell phones and tablet/notebook devices are almost universally powered by consumer-grade rechargeable lithium ion and lithium polymer batteries. Both chemistries offer a relative short operating life, and a fairly narrow temperature range. For example, the typical cell phone is not subjected to extreme temperatures and gets replaced every two years as part of a contract upgrade. Similarly, laptops are seldom exposed to the elements, and quickly become obsolete, so they can be powered by a rechargeable battery designed to operate for a maximum of five years and 500 recharge cycles.

Lithium-ion (Li-ion) rechargeable batteries are extremely popular for use in consumer electronics due to their high power output. The most popular type of Li-ion battery is the ubiquitous 18650 cell, which was designed and manufactured by the makers of laptop computers for use in their own products. These batteries operate for up to five years and 500 recharge cycles at temperatures ranging from -20C to 60C. As consumer-grade Li-ion cells age, they experience a gradual degradation of the cathode, which makes the battery less receptive to recharging, and thus reduces battery operating life.

Another form of rechargeable cell, the lithium polymer battery or laminate cell, is mainly utilized in consumer electronics. Lithium polymer batteries utilize a highly flexible material that can be rolled or stacked like a deck of cards, with the positive and negative terminals protruding from the cell as tabs, enabling these cells to be custom shaped to be very thin, or quite large, depending on their intended use. This flexible material is also more susceptible to being punctured than a battery encased in a steel or aluminum can. If a lithium polymer cell gets punctured, an internal short circuit can occur and/or the battery can self-discharge prematurely. A lithium polymer cell can also swell in size if the anode reacts with moisture.

Industrial-grade rechargeable cells

For economic reasons, manufacturers of consumer-grade Li-ion batteries never sought to improve the technology for industrial applications -- including lower self-discharge, high cycle rate, and hermetic sealing -- as it would have added incremental cost to these mass-produced batteries.

Recent growth in industrial applications requiring a more rugged lithium-ion (Li-ion) cell has led to the development of an industrial grade rechargeable Li-ion cell: the TLI Series rechargeable battery. TLI Series batteries deliver up to a 20-year operating life, with 5,000 full recharge cycles, a temperature range of -40C to 85C, the ability to deliver up to 15A pulses from an AA-sized cell, and a glass-to-metal seal to withstand harsh environments. In addition, these batteries do not suffer from the same aging issues as consumer-grade Li-ion batteries.

Fully understanding the performance advantages of newly developed industrial grade primary and rechargeable batteries versus standard consumer-grade batteries is essential to ensuring that the ideal power management will be selected based on application-specific requirements.

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