Testing Times | Thinking Carefully About Battery Holder Design

The minimum and maximum, length and width for common batteries is relatively wide

Ensuring your product is safe and reliable means thinking carefully about battery holder design. To help purchasers meet relevant standards, Memory Protection Devices has expanded its test capabilities

The quality of any battery powered electronic product will be judged insufficient, if it fails thanks to a faulty or flawed battery holder. This means the battery holder you specify must be up to the job. To help customers ensure this is the case, MPD has enhanced its test facilities by developing several custom test fixtures.

To test new battery holder designs MPD fabricated minimum and maximum sized battery slugs. This is important since the minimum and maximum length and width for common batteries is relatively wide.

The slugs save time and money by making it unnecessary to shop for several brands of batteries to confirm a design works with common batteries. They also weigh more than a regular battery, generating more force during drop testing. As well as being more durable, they have no power and will not short circuit, leak or require storage-handling precautions.

Meeting standards

So, just how are battery holders put to the test? The UL standard determines whether batteries will stay in a holder. It involves 50 insertion-extractions of the battery, followed by contact retention, conditioning, vibration and jarring tests. Coin cell battery holders are also subject to a 60in drop test using a fixture per UL2069.

MPD has developed test fixtures to work to the standard, using wing nuts for quick mounting the same PCB to either the jarring or drop test fixtures.

The EIA EIA-540J000 specification is another test methodology. Its purpose is to provide standard test methods, gages and performance requirements for battery holders regarding vibration, shock, contact resistance, solderability, temperature and humidity.

The major difference between the UL and EIA tests is that continuity is continually monitored during vibration and mechanical shock in the EIA specification. There are minor differences in contact resistance and solderability requirements and the EIA also has separate requirements for coin cell holders and cylindrical battery holders, under EIA-540J0AA and EIA540JAB.

User considerations

Clearly, there is much to consider when designing new battery holder products. When it comes to portable medical devices, such as glucose meters, thermometers or wearable drug delivery systems however, the stakes are even higher. They must be designed according to FDA-21 regulations, with a need to assess human factors, such as age and functional capabilities, that could impact the safe and effective use of the device.

Toy safety is another area where requirements are specific to the application. ASTM F963 standard focuses on markings, circuit protection and harness wiring with the emphasis on limiting access to batteries without tools. There are requirements for battery holders relating to the flammability of connectors and wires.

Finally, intrinsically safe apparatus is covered by UL913 which covers equipment destined for use in class one, two, three or division one hazardous locations.

In any application, batteries are considered safety critical components by compliance laboratories. Plastic battery holders have safety requirements when part of a circuit containing any kind of battery or battery charging circuits. MPD therefore aims to help by providing drawings containing the necessary product safety information, ultimately making design and documentation easier.