£75 ???

[[2068]]

Trying to be a bit safety minded, I bought a new battery for the PLB at SIBS today, as the existing one "expired" June 2011.

Being a curious sort, I completely ignored the "do not tamper" signs on the outside of the old one to see what I was getting for my £75.

I'm not sure what I was expecting.
Some sort of custom iPhone style battery?
An integrated charging circuit or monitoring?

Answer: None of the above

 

[Ripster]

So what did you find?

 

[Seahope]

So what did you find?

I think the picture gives it away. A load of standard AA batteries crudely wired in series. Seems a real rip-off to me.

 

[Ripster]

I think the picture gives it away. A load of standard AA batteries crudely wired in series. Seems a real rip-off to me.

Ahh right when I looked five mins ago there was just a red X there - so just a few regular lithium AA cells connected together - typical. £75 quid is a bit steep.

 

[[2068]]

... sorry, link to pic earlier was duff.
Fixed now.

 

[Ripster]

Just looked these up and you buy 4 ultimate lithum energisers for under 7 quid retail. Unless these are special ones or something.

 

[GrahamHR]

Yes, but there is special marine hot melt glue holding them in place ( plus a special marine yellow plastic piece they are mounted to)

Graham

 

[[2068]]

That glue must be very, very, special.
Maybe it enhances the transmission of 406Mhz signals ?

 

[elton]

I expect the cells are either soldered or welded onto the rails, and the unit will be vibration/soak tested before dispatch. A simple battery holder with springs and contacts as found in a torch wouldn't be reliable in this kind of application.

 

[oGaryo]

I expect the cells are either soldered or welded onto the rails, and the unit will be vibration/soak tested before dispatch. A simple battery holder with springs and contacts as found in a torch wouldn't be reliable in this kind of application.

wouldn't it be the case though if one of the batteries were to fail or one of those welds/solder joints went dry the the whole battery pack would be usless.. fewer welds/solders in a single cell battery would be more reliable would it not?

 

[[2068]]

I accept that, but even so, a price nearer £40 would seem more reasonable.
The batteries look to be welded together somehow.

 

[oGaryo]

Trying to be a bit safety minded, I bought a new battery for the PLB at SIBS today, as the existing one "expired" June 2011.

another point of note is the batteries that have been used are marked as being good until 2021 by the manufacturer... I wonder what then is the reasoning behind shaving 10 years off that life expectancy?

 

[elton]

wouldn't it be the case though if one of the batteries were to fail or one of those welds/solder joints went dry the the whole battery pack would be usless.. fewer welds/solders in a single cell battery would be more reliable would it not?

"Soak testing" would involve subjecting the battery pack to sustained vibration for a period of time.
The joints wouldn't go dry. Soldered joints are either dry or they aren't. Poorly welded joints will fail in the soak test.
The pack appears to contain 7 cells, giving a total voltage of 10.5 V. Perhaps they had a specific requirement for this voltage, which isn't available in off-the-shelf batteries.

 

[Ripster]

Is it relatively straightforward to solder to a AA battery like that? Can you get the contacts hot enough to make a weld with a regular solder gun without damaging the Cell?

 

[elton]

Is it relatively straightforward to solder to a AA battery like that? Can you get the contacts hot enough to make a weld with a regular solder gun without damaging the Cell?

You can't weld with a solder gun. Soldering will heat the cell casing and could be dangerous, or damaging to the cell. Spot welding can be done extremely quicky, with very little excess heat to dissipate.

 

[Ripster]

You can't weld with a solder gun. Soldering will heat the cell casing and could be dangerous, or damaging to the cell. Spot welding can be done extremely quicky, with very little excess heat to dissipate.

Ah OK. Thought that might be the case - thanks.

 

[oGaryo]

" Soldered joints are either dry or they aren't.

that's not my point, my terminology maybe suspect but dry, cracked or whatever term used, a solder joint can and will fail over time... more joints = greater possibility of failure

lets face it, it's a cheap bodge job when compared to a phone battery style arrangement.. if the right battery doesn't exist at the right voltage, then they could have got some outfit in china to make it

I'm with flowerP on this one, it's a rip off.. next question is am I surprised? nah, course not

 

[elton]

that's not my point, my terminology maybe suspect but dry, cracked or whatever term used, a solder joint can and will fail over time... more joints = greater possibility of failure

lets face it, it's a cheap bodge job when compared to a phone battery style arrangement.. if the right battery doesn't exist at the right voltage, then they could have got some outfit in china to make it

I'm with flowerP on this one, it's a rip off.. next question is am I surprised? nah, course not

Electronic devices contain hundreds or thousands of soldered joints. Proper manufacturing techniques and testing ensure reliability.

A 9V (PP3) battery contains 6 cells assembled together. There's no such thing as a 9V cell (to the best of my knowlege).

 

[oGaryo]

Electronic devices contain hundreds or thousands of soldered joints. Proper manufacturing techniques and testing ensure reliability.

yup, spent 3 glorious years repairing them, pcb's that is using traditional and software driven vacuum beds... IC's and analogue components... they were spec'd to go in aircraft so went through rigourous testing... still failed though, mostly due to solder joints gone bad.... one of the most brain numbing jobs I've ever had the displeasure to perform

 

[grumpy_o_g]

I'd be much happier with spring contacts than soldering or welding in those circumstances. It would need to be a decent spring but, if you've ever seen the punishment magazine springs get, you'd be pretty comfortable trusting a good one. An SLR mag spring was left under compression for 20 years and still worked perfectly afterwards.

I'd be far more concerned about how easy it was to open the case - PLB's can get knocked about quite a lot and I wouldn't be too happy if it was full of seawater when I came to use it. There's a good chance I wouldn't be able to get my money back either!!