Nuccio wrote:
I wonder why the McMurdo manufacturer specifies to replaced it every five years.
Nuccio wrote:
the considerable expence of about 200€.
Yes, I can’t possibly see any reason why they might do that – anybody else got a clue? 
The effect on you of having your entertainment device lose power compared to your McMurdo failing before the rescuer gets homed-in on you?
Maoraigh wrote:
Maoraigh10-Dec-21 21:0312
The effect on you of having your entertainment device lose power compared to your McMurdo failing before the rescuer gets homed-in on you?
Because of my techincal skill, I am led to believe that both religions and business are based on the fear of human beings. A battery that has 20 years of shelf life is thrown away after only five years. I see no technical reason to obey unreasonable prescriptions which are often also supported by regulatory authorities.
On 20 years of duration I would have put a safety factor of 10 years instead of 5 for the replacement.
In any case, as Peter says, one can measure the voltage at the terminals to see if there is any degradation.
I will use the batteries that I removed in my headphones and tell you how long they will last. Keep in mind that these batteries would have two years of remaining life of the 20 declared and have never been activated.
Of course you are right, Nuccio.
Testing the voltage annually should be 100% safe. It is difficult to pull wool over the eyes of an engineer 
The only gotcha is that most maintenance companies will not sign off an Annual unless the batteries are “in date”. This “got you over the barrel” applies to many things in GA.
Keep in mind that these batteries would have two years of remaining life of the 20 declared and have never been activated.
I think there are two aspects which may be relevant:
The shelf life only really applies before the battery is used for the first time. When discharging, the Zinc suspended in the alkaline potassium hydroxide electrolyte gets more prone to corrosion, which releases hydrogen and leads to cell rupture at the seal. This is particular pronounced if the cell has a high discharge rate (even temporarily, for example in a radio during transmission) and when discharged deeply at the end of its life.
So if the battery is not completely disconnected from any circuitry and has any discharge at all, the actual life will be shorter than the shelf life. As @Peter writes, the ELT may draw some power, and there will be the occasional test, too, so five years appears prudent.
But the scandal here is not that batteries get replaced prematurely out of an abundance of precaution.
The scandal is that a part containing batteries is produced where the batteries, which are generic and cheap, cannot be replaced, forcing you to buy the part from the manufacturer at massively inflated prices. Similar to Garmin memory batteries in GNSxxx.
I’ve no experience with 3d printing, but no doubt many here do.
How difficult would it be to design and print a replacement compartment which allowed the user to easily replace the batteries? I mean design a replacement battery compartment with fitted the max g perfectly but had a user accessible door to replace the batteries?
It seem like it would be a saleable design (if people do actually sell designs).
Has anyone replaced their own PLB battery? I have a McMurdo Fastfind 220 and found a battery supplier in the USA for $50 – and I assume with shipping it will be $80, but much cheaper than an “official” channel.
Looks easy, but happy to get actual feedback from you.
https://beaconbatteryreplacement.com/instructions/
Thanks, Mickey
I am wondering the same thing at the moment.
I got a Resqlink+ and the battery according to the label is expired, however the unit tests ok when I try the test button (both GPS and just signal).
Looking at the manufacturers website, I’d have to ship the unit internationally to get it replaced, however on youtube it looks very easy to replace the battery yourself. Bu then of course you don’t get a new sticker with the expiry date.
On the other hand, the PLB is not an airworthiness item, as I carry an ELT as well. So how serious is the battery limitation? And how can you get the sticker if you do the replacement yourself?
How hard can it be. Like an idiot I tried to change the flat battery in my computer. Changing it was very easy. But the computer never worked again. I could take it to someone who knows, but it is an old computer and not worth a great deal now,which is why I took the risk of changing the battery myself.
My key concern would not be the sticker but rather if I could waterproof the housing again after replacement. This is also hard to test w/o the risk of bricking the device.
