PLB battery discharge test

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KAM

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I'm going to do a discharge test on my old PLB batteries. I was just wondering if any electronics types out there could give me an estimate of a suitable discharge current which might be somewhat representative of the PLB. Transmitting on 406, GPS, flashing light etc.
 
Not sure why you want to do this. Are you talking about testing batteries which have already been replaced on age grounds? If so, what's the point?
 
I've taken out the expired batteries and am interested to see how well they have stored in my boat environment.
 
I suppose I could just compare against the battery spec but in order to see how long the PLB might have functioned for it's better to discharge at something approximating to the expected current draw when the unit is functioning.
 
The PLB operation won't be a steady current. It is a 406MHz transmission at a few watts, but at quite a low duty cycle.
The 121.5 is fairly continuous but not a lot of power.
I think the pulsed nature of the discharge in PLB operation might be significantly harder on the battery than a steady discharge?
Could you not think of a use for the battery?
It's a shame they don't fit things like my camera which gobbles AAs.
Only thing I can imagine it might come in for is xmas lights.
 
Typical full sized EPIRB might use CR123 batteries or smaller similar lithium battery. One old one I have seen had 8x CR123 in series parallel arrangement. CR123 are typically 1500mah.
Physically smaller battery on a PLB might be a lot less capacity. Unless you can find a claimed capacity on the battery that is the kind of range you might expect. As you would expect a PLB to operate for 15 hrs this might suggest a discharge current of 100ma or less. I would try about 50ma for your test. Or less if it physically a tiny battery.
ol'will
 
So the batteries that came out were due to be replaced in 2016 but were still showing full on self test. Under the 2016 sticker was a label that said replace by 2015. The replacement batteries were rated at 1000mah. Discharge test on the old battery was at 80 ma for 12 hours at 16 deg C at which point voltage had dropped from 3.2V to 2.8V. PLB had been stored at an average temperature of 10 degrees C. Seems like there was a reasonable safety margin. Higher rate test at lower temperature tomorrow.
 
KAM said:
I suppose I could just compare against the battery spec but in order to see how long the PLB might have functioned for it's better to discharge at something approximating to the expected current draw when the unit is functioning.
Click to expand...
Build a cage around it with wire mesh and set it off .. then you will see how long it really would have lasted
 
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