9v Batteries for 406 EPIRB

[theotter]

One for the electro technos! Given the almost impossibility of finding the correct 3 x 3v batteries required for my McMurdo 406 EPIRB (complete with tabs), I'd like views on the viability of a plan without numerous comments of the 'what price ones safety' type! I reckon I can get 6 x 9v DD batteries (the small rectangular type) in the unit. If I connected them up in parallel, is there any reason why they shouldn't do the same or similar job other than the fact they don't have the same shelf life and one would probably change them every year. The cost implications are huge, e.g. £10 for 9v Duracell v. £100 for a type if you can get them v. the cost of a new EPIRB just for getting the batteries changed by an 'expert'. I look forward to any informed responses.

 

[awol]

Presuming the cells are "D" type lo26sx-SAFT, they have a 7.75Ah capacity (cf with ~0.5Ah for a P cell) and are very low self discharge. Hope you never need it!

 

[Heckler]

Presuming the cells are "D" type lo26sx-SAFT, they have a 7.75Ah capacity (cf with ~0.5Ah for a P cell) and are very low self discharge. Hope you never need it!

Looks good! http://www.battery2batteries.com/saft-lo26sx-sts-battery-3v-lithium-d-cell/
Stu

 

[lw395]

The transmit current on an EPIRB is not small. The Lithium batteries are chosen with that in mind.
£100 for the right battery that lasts 5 years is only 20 quid a year.
Plus if you pay to have the battery changed, I think they properly test the whole unit?

 

[theotter]

Thanks for the responses but you are not reading the question. My point was that I have not been able to trace the SAFT Lo26 SX, unlike 6 years ago from RS Components or anyone else, and if you follow the link provided by skipper_stu the provider is an American company that doesn't post outside the USA! The nearest equivalent from RS Components are not supplied, by them at least, with tabs. Been all through that so the gist of the question was the viability of 6 x 9v batteries in parallel. The voltage is fine but would they have, for example, the oomph to provide 24 hours of transmitting??

 

[contessaman]

Let me know how you get on. I have the mcmurdo g4. Mines past its battery expiry and I'm appalled at the cost of a new battery. It looked to me like the original battery is made of three x 3v cells that each have the form factor of a 1.5v 'D' cell but as you have found ill be buggered if i can find a place to purchase them, solder tagged or otherwise.

I love how so many people take exception to somebody daring to change a battery themselves or indeed make up the battery cell. If the voltage and ampere hour is matched then it will work as intended. Thought this was the 'practical boat owner' thread! Probably why the last time I picked up a copy in the newsagents, I was shocked to see a magazine about a third the thickness of the PBO I remember with nothing but adverts and a few naff handheld vhf or sailing boot reviews.

 

[rogerthebodger]

Thanks for the responses but you are not reading the question. My point was that I have not been able to trace the SAFT Lo26 SX, unlike 6 years ago from RS Components or anyone else, and if you follow the link provided by skipper_stu the provider is an American company that doesn't post outside the USA! The nearest equivalent from RS Components are not supplied, by them at least, with tabs. Been all through that so the gist of the question was the viability of 6 x 9v batteries in parallel. The voltage is fine but would they have, for example, the oomph to provide 24 hours of transmitting??

I did a google search that showed up some suppliers in the UK

https://www.google.co.za/search?q=S...fqPPXAhXIVhoKHUeuBdEQBQglKAA&biw=1920&bih=949

 

[lw395]

Thanks for the responses but you are not reading the question. My point was that I have not been able to trace the SAFT Lo26 SX, unlike 6 years ago from RS Components or anyone else, and if you follow the link provided by skipper_stu the provider is an American company that doesn't post outside the USA! The nearest equivalent from RS Components are not supplied, by them at least, with tabs. Been all through that so the gist of the question was the viability of 6 x 9v batteries in parallel. The voltage is fine but would they have, for example, the oomph to provide 24 hours of transmitting??

No.
Here's some data on a typical PP3.
Sorry can't make the link work, but look at Farnell they have datasheets for Duracell industrial batteries.
Compared to the 9Ah of the lithium batteries, they are a joke. I'd guess you might get somewhere around one tenth of the effective capacity.
They possibly have too high an internal resistance to run a EPIRB from 6 of them anyway.

PP3's are designed for low current applications.
EPIRB batteries are designed for high energy density, high power and long storage life. They are expensive for a reason.

 

[macd]

EPIRB batteries are designed for high energy density, high power and long storage life. They are expensive for a reason.

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.

 

[rogerthebodger]

Presuming the cells are "D" type lo26sx-SAFT, they have a 7.75Ah capacity (cf with ~0.5Ah for a P cell) and are very low self discharge. Hope you never need it!

Looking at the info from SAFT for 3v Li batteries I found Li-Mno2 D cell batteries that are 3 volt but have a a capacity of 13 Ah almost twice the SO26SX as I also have in my 406 EPIRB.

May be technology has moved on and the SO26SX have been replaced with better ones. The increase capacity would allow the EPIRB to continue to transmit for almost twice as long as originally specified.

SAFT LM 33550 or SAFT M20

https://uk.rs-online.com/web/p/d-batteries/8602815/

or here

http://ukbatterysales.co.uk/brand/saft/saft-li-mno2-range/

 

[awol]

.... and only £110 for 3!

 

[lw395]

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?

 

[theotter]

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??

 

[ShinyShoe]

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...

 

[lw395]

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.

 

[wotayottie]

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.

 

[theotter]

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.

 

[awol]

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.

 

[trialframe]

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

 

[lw395]

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.