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Old 28-03-2016, 11:17   #16
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Re: EPIRB Battery Test Results

Quote:
Originally Posted by a64pilot View Post
I think storage temperature has a lot to do with shelf life of batteries, don't let them get hot and they will last a whole lot longer than if you leave them in your hot car often


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Hi a64,

I agree about temp and battery life.

Your comment reminds me to add some addenda to my original blog post. In this case the EPIRB I tested had spent its entire life [batteries expired in Apr-2008] until 2012 in the Bahamas, in the raft, which is a valise model that was stowed below decks when not on a passage. It was in the PNW from 2012 until tested Nov-2015.

I suspect this is why battery shelf-life is modestly rated: I speculate the shelf life is predicated upon maximum storage temp [55C (131F) in the case of the unit tested.]

Thanks for augmenting the details.

Cheers!

Bill
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Old 28-03-2016, 11:53   #17
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Re: EPIRB Battery Test Results

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Originally Posted by Jim Cate View Post
Bill, thanks for that report. It supports my gut feeling that the specs are VERY conservative. Something that I have questioned before: the battery life is purported to be X years, but the required replacement period is X/2... how come?

The only question that comes to mind about your test is wondering if removing the antenna meant that the transmitter did not actually come up to full working power. The SWR seen by the output stage of the xmtr would be very high, and in some circuits, this causes the output to be ramped down. True in my ham rig and in my AIS... no idea about the EPIRB.

Jim
Hi Jim,

I agree that the findings are interesting, but I, too, wonder how representative they are...

RE: Battery shelf life ratings: From what I've gleaned- without finding anything specific yet- it appears the manufactures may establish battery shelf life on worse case storage environment [55C/131F in the case of the unit tested.]

RE: Was it transmitting without an antenna? I pondered that as well. I may make an inquiry of the manufacturer but given the age of the unit, any response may not be representative of newer units.

I proceeded with the reasoning that EPIRBs are essentially designed to perform once. Given the 5 watts max transmit power [for 406MHz], I'm guessing they wouldn't bother with signal attenuation logic [hence the remove antenna and wrap in foil instructions...] because, considering the circumstances when one would be activated, any transmission is better than no transmission... [But I am only guessing; something I don't like to do...]

This is my gut feeling from years of being a link in various liability chains; I wouldn't want to have to defend my product by describing why it was designed to self-preserve instead of perform at all costs... But I am back to guessing...

If I had had access to a small portable AM or FM radio, I would have put it in the oven and listened for transmission 'clicks.' [I understand any station on AM; 99.5 on FM...] But without an antenna, that might not be definitive either... I was guessing again- sponsored by the foil recommendation- that some signal might escape. [Or perhaps the manufacturer was mitigating liability (CYA) with an erroneous foil suggestion...]

Anyway, with this [potentially flawed] logic I proceeded to light up my oven with a xenon strobe for 4 1/2 days...

Thanks for the feedback. I will add this to the addenda in the original blog post in coming days...

May we never have to test these things for real...

Cheers!

Bill
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Old 28-03-2016, 12:07   #18
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Re: EPIRB Battery Test Results

Quote:
Originally Posted by Nicholson58 View Post
So. When will they come out with an EPIRB that:
rides on the boat electrical system
stays fully charged at all times
runs an automatic diagnostic including battery health
permits user replacement of batteries rejected by the test


Aside from the absurd cost to send one in for service, the time to ship and wait for it to return is an extreme imposition and added expense. AND, so far, every EPIRB I have tried to have serviced was:
still on its first battery
declared to be obsolete
OR battery obsolete.


I regard this equipment as critical. I also think that contrived obstacles to its maintenance in order to maximize cash flow to the makers (same as life rafts) is close to criminal theft. I really don't like having a gun to my head while someone probes my wallet.
Hi Nicholson,

I share your frustration dealing with any proprietary batteries...

Since I have another EPIRB expiring later this year, I have been researching/shopping replacements.

I found one with an extended run time and user replaceable batteries that is still on my short list: Ocean Signal E100-G [This model is also available in Class 1 for cold climates i.e., -40C (or F as the scales meet at this temp.) Most EPIRBS we buy are Class 2; -20C/-4F]

[I am putting together a separate future post documenting my efforts, finding, and ultimately decisions in case anyone is bored...]

Cheers!

Bill
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