Chuck Husick: Techno-Talk, September 2006 from BoatUS Magazine - Updated February 2010

EPIRB Batteries

An Emergency Position Indicating Rescue Beacon (EPIRB), or the smaller but equally effective Personal Locater Beacon (PLB) can save your life, but only if it has the energy to operate its transmitter when you activate it. This is especially important for the many boat owners who purchased these life-saving devices in 2001 as EPIRB batteries have a five-year service life. As the one in your EPIRB may now need to be replaced, the job should be done by a service shop approved by the manufacturer.

The technical and performance specifications for all EPIRBs and PLBs are government regulated to ensure that the beacons are compatible with the worldwide satellite monitoring system. It’s a lifesaving device, therefore the specifications are exact. For example, the five-watt 406 MHz transmitter must operate for at least 48 hours (24 hours for the smaller PLB) even in the most adverse conditions — temperatures as low as -40°C (-40°F) or as high as 55°C (131°F) — and after five years’ storage at temperatures as low as -50°C (-58°F) and as high as +70°C (+158°F).

At this time batteries capable of providing the required combination of very long storage life and assured power delivery must be assembled from carefully made Lithium cells. The need for using only the correct type of battery is emphasized in the a November 2009 U.S. Coast Guard Marine Safety Alert. In the notice, a foreign battery was discovered during a manufacturer’s inspection. Not only did the foreign battery measure at a different voltage the case was cracked allowing water intrusion. Unapproved battery replacement such as this could result in a critical failure of life saving equipment.

Not long ago, the battery in my 2001 ACR RapidFix 406 EPIRB was due for replacement. Wanting to know as much as possible about the battery replacement process, I arranged to take the EPIRB to the ACR factory in Fort Lauderdale where I accompanied it during the two-plus hours it took to perform the incoming inspection, perform the same series of tests used for new production units and install the new battery.

The beacon was logged into the recertification process by recording the model and serial number, NOAA number, manufacturing date code and the name of the registered owner in the receiving log. A quick check of the test / activate switch (a flip lever on this model) revealed that the tension of the spring that holds the manual activate switch in the off position was too low and would not pass the final inspection the unit would undergo after the service work was finished. The spring was replaced, and an entry made on the quality control traveler that would accompany the beacon during its voyage through the recertification process. The digital code that identifies the unit was verified when it appeared on the computer screen.

The Quality Control seal on the case screw was removed, the unit opened, the battery removed and everything examined for evidence of damage or deterioration. All was in order. A new battery was slipped into the case and the battery information entered into the log sheet. The beacon, less its battery, was installed with a radio frequency shielded test enclosure that provided a power source and a dummy load to absorb the energy from the transmitter. It was then run through a computer controlled 45-minute test of every aspect of its operation, including frequency accuracy and stability, power output and overall signal quality.

With this test successfully concluded, the beacon was reassembled and tested to ensure that it was totally watertight and that the circuit that would activate the beacon when it was immersed in water was functional. The technician who tested the unit signed off on the log and sent my beacon on for a final review of the unit and all of the paperwork, a process identical to that used for new production units.

The work that was done went far beyond just replacing the battery. The companies that make these units know that lives may depend on their product working precisely as designed, up to five years after you put it on your boat. The price for the service, about $300 (this will vary depending on the type of unit; PLBs will usually cost less to service) would be high if all that was required was a new, garden variety battery. Considering the need for the special battery and the extensive testing done to assure that the unit would work when needed, the price I paid was a bargain.

The batteries in some PLBs are owner replaceable. If you choose to replace the battery yourself be certain that the new battery is identical to the one being removed from the device and that it has a current date code. While replacing the battery may save money, the full test performed by a qualified service station is a very worthwhile investment, it's your well being if not your life that may be at stake if you need to activate the PLB.

The batteries used in most EPIRBs and PLBs are Lithium Primary Batteries and may be restricted on commercial aircraft. Newer PLBs and EPIRBs identified by manufacturers as Non-Hazmat and can be taken aboard commercial aircraft. Owners of older EPIRBs and PLBs should check with the manufacturer to see if there are restrictions. In either case someone traveling with an EPIRB or PLB should have the Material Safety Data Sheet (MSDS) with them to speed up inspection at the airport security checkpoints. Detailed regulations can be found in Title 49 CFR172.102. The TSA also has an online guide outlining traveling restrictions of all item with lithium batteries: (http://www.tsa.gov/travelers/airtravel/assistant/batteries.shtm). The bottom line, the high energy storage capacity of the batteries used in EPIRBs and some PLBs that may save your life can also poses significant safety hazard in the event of an internal short circuit in the battery or in the device in which it is installed. If you must carry one with you on a commercial aircraft place it in your hand luggage.

By Chuck Husick


Chuck Husick is a pilot, engineer, sailor and former president of Chris Craft Boats.

© Copyright BoatUS Magazine 2006   - (updated February 2010)