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  1. #11
    Join Date
    Jan 2005
    Location
    Me Edinburgh, boat JWD
    Posts
    4,552

    Default Re: 9v Batteries for 406 EPIRB

    .... and only £110 for 3!

  2. #12
    Join Date
    May 2007
    Posts
    28,416

    Default Re: 9v Batteries for 406 EPIRB

    Quote Originally Posted by macd View Post
    I suspect you flatter them, for a substantial part of that 'reason' is profit. Or should that be 'profiteering'? My last EPIRB, a reputable Stateside brand, had a bundle of Li-ion cells wrapped as a unit. The cost of OE replacement was astronomical. Yet the wrapping contained no more than a few freely-available cells. The equivalents from Sanyo (also a reputable brand) cost 13 quid, delivered. I suppose I did have to lash out for some tape to bind them together.

    P.S. If I remember correctly, the OE cells were made by...Sanyo.
    If you look at the Saft website for example, you'll see that there are many flavours of LiIon battery.
    Just as there are lots of different brands and qualities of car batteries or torch batteries.
    But the 3 C Cells in a McMurdo EPIRB are likely to cost over £60.
    If you think that's a lot, you want to see what really expensive batteries are like.
    The cost is ramped up by the testing and QA that proves these things will have the shelf life and service life.
    I think a full service and battery change is about £140?
    So that's about £80 labour to change some removable bits, perform a full system test etc.
    That should include a proper transmission test. You wouldn't want your EPIRB to be transmitting gibberish.
    Also a leak test.
    Plus the paperwork.
    Have you got an audit trail to prove your sanyo cells were genuine and date of manufacture?
    There is a lot of counterfeit stuff kicking around.
    Is your tape going to hold them in place for 5 years in the tropics? Or at freezing temperatures.
    It's industrial safety kit, all t's must be dotted etc.
    Would you sell your boat with a DIY serviced EPIRB?
    What was the value of the gas that wasn't in the Louisa's liferaft? Nuppence, the value is in procedures which would have made damn sure it was in there.
    No doubt it's a profitable business. You would not get involved in such work for fun.
    How does it compare with say what you get from a BMW dealer's workshop for £140?

  3. #13
    Join Date
    Nov 2004
    Location
    Lymington
    Posts
    96

    Default Re: 9v Batteries for 406 EPIRB

    The nearest equivalent I referred to is the SAFT M20 HR but try as I might I cannot source them, with tabs, in spite of the data sheets showing images of them with tabs in several configurations. Without tabs they are a 'no no' because according to the data sheets soldering to the batteries without specialist equipment is highly dangerous. I would be happy to pay the £100 for these batteries (with tabs) but unless someone proves to me otherwise, they are unobtainable unless you buy 500 ish! Thanks for your inputs and links etc but unless you have gone the next step and actually tried, like I have, to actually get hold of any of the fore mentioned batteries you will realise it is not straight forward. So, it is in desperation/exasperation that I have suggested the use of 9v batteries in parallel. Thanks to lw395 for an informed remark which I respect. Is there anyone else out there who can convince me one way or the other that the 9v battery course is viable or not??

  4. #14
    Join Date
    Nov 2013
    Posts
    1,048

    Default Re: 9v Batteries for 406 EPIRB

    Quote Originally Posted by theotter View Post
    Is there anyone else out there who can convince me one way or the other that the 9v battery course is viable or not??
    I doubt you'll even fire the transmitter. If you do I suspect it will be dead very soon.

    That D Cell linked previously is 7.5Ah, rated at continuous 2.5A and pulse to 15A.

    Your EPIRB has ~ 5W transmitter in it (similar to a HH VHF). At 9V that means you MUST be drawing 555mA just for perfect transmission power. If it is that efficient I'd be impressed. 9V is an odd circuit voltage it will almost certainly be 5V or 12V and use some conversion electrics. and you need to do other things like GPS, flash strobes. At the point of transmitting I will be gobsmacked if its drawing less than 1A, and I'd not be surprised if it hits 2A. A standard PP3 is typically 400-500mA. But the chemistry will keel over if you ask for more than 100-150mA from a single one. So if you stick 15 to 25 of them together you should be about sorted.

    Last time I bought a half decent PP3 I think it cost £2.50, I'm not sure the economics are making sense, even if you magically had space to put 15 cells.

    Even if that level of crazy made sense, for such a safety critical application - I'd want to test it.... ...so maybe if I had 20 of these to replace I'd follow the logic. For a one off - find the right cell, or buy a full price replacement...

  5. #15
    Join Date
    May 2007
    Posts
    28,416

    Default Re: 9v Batteries for 406 EPIRB

    A few other points.
    Alkaline cells only achieve their shelf life if they are completely unused. So once you do the first self test, their life is shortened.
    When making shaky estimates of how much power is needed, don't forget the continuous 121.5MHz homing signal. Or that there is a small continuous current draw from the water activation circuit.

    I can understand people not needing a fully certified EPIRB. I've done a lot of miles without one.
    But I don't see the logic in spending a fair bit of effort to bodge one.
    If you want the comfort of knowing you have an EPIRB, the price of sending it to Sartech seems pretty good value.

    I've seen what's in these things. I have a pretty good idea of what the components cost in a factory.
    The battery is a big slice of the materials cost.
    I think if it was possible to do the job with cheaper battery technology, they'd be doing it.

  6. #16
    Join Date
    Jul 2007
    Location
    swansea
    Posts
    10,100

    Default Re: 9v Batteries for 406 EPIRB

    Quote Originally Posted by theotter View Post
    The voltage is fine but would they have, for example, the oomph to provide 24 hours of transmitting??
    No. 6 times 0.5 is half of what the correct batteries give and thats before the self discharge takes effect.

  7. #17
    Join Date
    Nov 2004
    Location
    Lymington
    Posts
    96

    Default Re: 9v Batteries for 406 EPIRB

    Thanks for the comments....I think they have pretty much nailed the question! Next question for me is do I have a battery replacement job done or buy a brand new one which can probably be cheaper. In the mean time if anyone finds either of the SAFT batteries mentioned afore.....please shout loudly. Happy Christmas to you all and good sailing.

  8. #18
    Join Date
    Jan 2005
    Location
    Me Edinburgh, boat JWD
    Posts
    4,552

    Default Re: 9v Batteries for 406 EPIRB

    You could experiment with your PP3 pack. Put it and set it off inside a metal box, preferably earthed, and see how long it flashes. That could leave you with the same problem that beset Schrodinger, though.

  9. #19
    Join Date
    Nov 2003
    Location
    Weymouth UK
    Posts
    140

    Default Re: 9v Batteries for 406 EPIRB

    I've got a 9v Kannad battery pack dated Aug 2020 comprising 9x 3v lithium batteries - will this fit? It has 3x connectors.

  10. #20
    Join Date
    May 2007
    Posts
    28,416

    Default Re: 9v Batteries for 406 EPIRB

    Quote Originally Posted by trialframe View Post
    I've got a 9v Kannad battery pack dated Aug 2020 comprising 9x 3v lithium batteries - will this fit? It has 3x connectors.
    Do you know its history?
    One that has been partially discharged is not going to be the best idea. I don't think it's easy to determine the true state of charge of a used battery.
    Fair enough, we don't need 48hr run time in the English channel, but it's not a line I'd care to draw for someone else.

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