Holding their own

Memory Protection Devices’ president, Thomas Blaha, explains how prioritizing application requirements optimizes battery holder selection.

When designing power management solutions involving AA batteries, engineers often focus on the battery rather than the holder. Often overlooked, the holder plays an important role ensuring system ruggedness and reliability.

Like most products, battery holders are designed to contradictory requirements. Ideally, they need to be small and light, yet survive shock and vibration while securing large, heavy batteries.

Quality battery holders can meet these requirements, but compromises invariably arise. Manufacturers must work from a prioritized list of features. For example, if the primary requirement is to hold the battery securely, then a secure screw-on cover may be necessary. An application requiring easy field replacement may require a looser fit with finger notches or an easily disengaged latching mechanism. This may involve trade-offs such as added size, weight and cost.

Battery holders can enhance a product’s robustness. Access doors can employ ribs to secure multiple batteries that could shift position and lose electrical connection. Such ribs have negligible impact on cost but can dramatically enhance ruggedness.

To provide high retention and shock resistance (typical in PCs and consumer electronics with a PCB mounted battery) it makes sense to pay slightly more for a robust solution to reduce the cost of support calls, product returns and dissatisfied consumers.

Another important decision involves termination. Battery holders can be secured with printed circuit pins, solder lugs, male/female snap fasteners, wire leads, SMT bump plates or customized fasteners. Each offers a unique combination of cost, ease of assembly, space and ruggedness, requiring careful consideration.

The electronics marketplace is saturated with poorly manufactured knock-offs and it is increasingly difficult to differentiate products of superior quality from inferior imitations. Buyers need to perform thorough due diligence to ensure optimum battery holders are specified. This review process should require detailed and verifiable answers to the following questions:

• Does the battery holder meet UL2069 standards for proper battery retention?

• Does the battery holder meet EIA-540J0AA and/or EIA-540JAB specifications for vibration, mechanical shock, contact resistance and solderability?

• Is the product an intrinsically safe apparatus as per ANSI/UL standards?

• Are superior grade materials being utilized? Plastic, contact, assembly materials, plating specifications, wire and encasement all should be reviewed.

Even if two competing battery holders appear the same, there can be subtle design differences that result in radically different performance. Relying on outside independent certification standards such as UL2069 will help ensure your selection does not just look like it will do the job but will actually perform in the real world. Similarly, carefully evaluating the quality of raw materials and manufacturing techniques will help ensure that your battery holder holds up to the rigors of the electronic assembly process.

Multi-million-dollar product recalls have been caused by incorrect selection of battery holders, so this additional verification will pay off in the long run. Properly selected, a battery holder will provide a highly reliable and cost-effective long-term power management solution.