Model lost from faulty pack

[Tony Smith 7]

That would be fairly easy to test. Many battery holders don't have enough travel in any case and still make firm contact even with either of the springs fully compressed. My GPS is like that, and the torch I just happen to have with me at the moment.

 

I was about to say that it probably applies to anything where the case closes on the battery, but I've just checked my camera and in that instance its right enough that the battery moving fully down could release the pressure on the opposite contact. It would need about 40G, so I'm not going to do an actual test as I suspect there'd be other damage first.

 

By the way, to put all this in perspective, remember that this discussion started with reports of models lost due to failure of purpose-made welded packs. I don't think any one is suggesting that a commodity battery case from Maplin would have been suitable. However a properly designed battery holder has advantages in ease of inspection, ability to choose your own cells and the ability to individually test and replace cells if you're so inclined.

 

Regarding insurance and liability, I really hate it when people bring that out as a trump card. Surely we should be doing our best to remain safe, rather than taking actions that we personally disagree with, just because we trying to guess how an insurer would react.

[Tim Mackey]

Ah I see Steve - but thats slightly different, as its actually describing how long the rx takes to reboot after a brown out, rather than at "start up". As the tx is still transmitting on the same channels, then reconnection should take only milliseconds, assuming its a spektrum and has the latest "Quick connect" firmware .

[Lee Smalley]

and has the latest "Quick connect" firmware .

 

 

 

Good cover there Timbo!!!!

[Peter Beeney]

 

 

How about a practical examination then, something like this - Take a Maplins AA 4 cell battery holder. Load it with 4 Sanyo Eneloop AA cells. (Or maybe any other quality cells). Charged, naturally! The wire connection is the polarised press stud type, so also use one of these, cutting the fabric cover off. Underneath the wire is crimped to two tags, cut the wire and solder on a couple of metres or so of standard model battery harness wire. Make a nice wet job of the soldering, using a smidgin of Powerflow flux. Place a small piece of card over the tags, making sure that the wires are not lying on any bare metal and then wrap the whole thing end over end with masking tape, again making well sure the wires are nicely supported and that any tugging will not transfer to the tags. Or alternatively just solder the new wire to the wire on the clip. Then wrap round the body with a couple more layers of masking tape and then again the whole with insulating tape. Fix a bulb holder on the ends of the wire, put a suitable bulb in so that it’s lit, take it out in the field and drop it from chest height. Continue to do this until the bulb goes out, proving that the circuit has gone open circuit. A slightly more sophisticated version might be driving the bulb via a transistor, wired in a latched or no-volt release configuration, so that in the event of a disconnection, however brief, the bulb will go out and not come back on again until it’s reset. Also alternatively dropping it on a concrete floor will give it a bit of a harder time, so to speak; as would dropping it out of a tree; well, planes frequently seem to want to start a relationship with a tree, and if it were wrapped in foam rubber, as modellers batteries often are, would that be significant……

That’s the knock test then, now you’d need to leave it for a year untouched, to give it the age test. How about placing it in the engine compartment of an earth mover, for a heat and vibration test? Let do the job properly while we’re at it. And then after all that, give it to me for the idiot’s test………

I think, to be absolutely fair, you would have to do an exact parallel test with a standard off-the-shelf unmodified pack, no extra support on the wires, for instance.

I have a feeling in me water that when either of these packs eventually goes open circuit under this sort of treatment, it stays open circuit, making the brown out, (or would that now be black out?) recovery time largely academic.

I’ve no idea how this would perform in these condition, but taking a semi-educated guess, I think it would do quite well. Maybe you might even need to take a charger with you, the pack might go flat first! Not scientific, in any way shape or form, but it might be an indication of just how substantial, or otherwise, these things are.

I think someone from Maplins has been reading this thread. Suddenly our local shop has a greater variety of battery boxes on sale.

All wishful thinking, I’m afraid, understandably no one is ever going to do this. But, if you did, you could then forecast with some confidence how good, bad, or indifferent the performance of battery boxes are in related discussions with regard to model aeroplanes!

PB

[Steve W-O]

Posted by Peter Beeney on 05/07/2011 13:41:07:

 

 

How about a practical examination then, something like this - Take a Maplins AA 4 cell battery holder. Load it with 4 Sanyo Eneloop AA cells. (Or maybe any other quality cells). Charged, naturally! The wire connection is the polarised press stud type, so also use one of these, cutting the fabric cover off. Underneath the wire is crimped to two tags, cut the wire and solder on a couple of metres or so of standard model battery harness wire. Make a nice wet job of the soldering, using a smidgin of Powerflow flux. Place a small piece of card over the tags, making sure that the wires are not lying on any bare metal and then wrap the whole thing end over end with masking tape, again making well sure the wires are nicely supported and that any tugging will not transfer to the tags. Or alternatively just solder the new wire to the wire on the clip. Then wrap round the body with a couple more layers of masking tape and then again the whole with insulating tape. Fix a bulb holder on the ends of the wire, put a suitable bulb in so that it’s lit, take it out in the field and drop it from chest height. Continue to do this until the bulb goes out, proving that the circuit has gone open circuit. A slightly more sophisticated version might be driving the bulb via a transistor, wired in a latched or no-volt release configuration, so that in the event of a disconnection, however brief, the bulb will go out and not come back on again until it’s reset. Also alternatively dropping it on a concrete floor will give it a bit of a harder time, so to speak; as would dropping it out of a tree; well, planes frequently seem to want to start a relationship with a tree, and if it were wrapped in foam rubber, as modellers batteries often are, would that be significant……

That’s the knock test then, now you’d need to leave it for a year untouched, to give it the age test. How about placing it in the engine compartment of an earth mover, for a heat and vibration test? Let do the job properly while we’re at it. And then after all that, give it to me for the idiot’s test………

I think, to be absolutely fair, you would have to do an exact parallel test with a standard off-the-shelf unmodified pack, no extra support on the wires, for instance.

I have a feeling in me water that when either of these packs eventually goes open circuit under this sort of treatment, it stays open circuit, making the brown out, (or would that now be black out?) recovery time largely academic.

I’ve no idea how this would perform in these condition, but taking a semi-educated guess, I think it would do quite well. Maybe you might even need to take a charger with you, the pack might go flat first! Not scientific, in any way shape or form, but it might be an indication of just how substantial, or otherwise, these things are.

I think someone from Maplins has been reading this thread. Suddenly our local shop has a greater variety of battery boxes on sale.

All wishful thinking, I’m afraid, understandably no one is ever going to do this. But, if you did, you could then forecast with some confidence how good, bad, or indifferent the performance of battery boxes are in related discussions with regard to model aeroplanes!

PB

 

 

 

 

And the Minister of Agriculture replied "Huh?"

 

(Wrex Tarr, 1963)

 

 

Though I do agree it would be a blackout, not a brownout.

 

Somebody mentioned earlier that the remote control story would be used as usual, I wonder why? Maybe because it often happens? Therefore a good example?

 

I also have amateur radio gear that uses packs with spring contacts, if it fails, I lose a QSO, nothing more. One radio I have, came with a soldered pack, also a pack that could take AA cells, supposedly for alkaline, but by snipping one wire, rechargeables could be used. These suffered mysterious output transistor failure, which was eventually blamed on the cells not making proper contact.

 

Last week I had a camera that did not work, the batteries had developed some kind of film (not corrosion) that needed a clean with 1000 grade wet&dry to make it work again.

 

On Sunday, my one son bought the baby a second hand drum machine from a boot sale. It did not work until the springs were cleaned ( they looked OK)

 

It's all really a futile argument, so easy to produce "evidence" in either direction, however I won't be using spring connector packs in my planes, which will seem as illogical to those who do, as their views seem to me. Hopefully neither decision will be the cause of a crash.

 

What should we be suggesting to new people though?

[Lee Smalley]

Or you could just buy a pack for 10 quid and save yourself the hassle Pete

[Malcolm Fisher]

The electrical items which didn't work in Steve W-O's post were probably suffering "micro corrosion" on the contacts. This was pointed out many years ago as being possible with transmitters which had individual cells with the provision for charging in situ. Removing the cells for charging is usually sufficient to overcome this problem and was recommended at the time it first came to notice.

I have experienced this situation with rechargeable cells used to power portable radios. Usually rubbing the terminals on a clean cloth is sufficient to restore cleanliness of the contacts and restore electrical continuity..

Pete - I like your idea for the test, but I suspect the bulb would break before anything else went awry.

Malcolm

[Peter Beeney]

Maybe the Min of Ag understood all about farming, and nothing about batteries? He ought to read this thread….

Brown outs I’ve always been sceptical about anyway, but I think that’s for another place.

The problem I have about buying a new pack, from the evidence I’ve seen and read about, is that there is a chance that within minutes I could be scraping up the remains of an expensive aeroplane, which I would consider a great deal of hassle indeed. Although I would instantly qualify that by saying that I would consider that probably the vast majority of packs are going to be eminently satisfactory. It’s just the odd one that gets the bad press. What I like to do is to solder together some cells of my choice, making up my own pack, and then giving it what I consider the appropriate aftercare, with the view of trying to avoid all the very troubles that have been discussed. I’ve never found this to be much hassle.

Regarding the 10 quid pack, I’ve recently bought 2 AA Ni-MH cells, UltraMax, for 99 pence. 4 cost £1:98, would you believe? On my first checks they are well up to speed. They are not advertised as being long shelf-life types, but straight out of the bubble wrap they were virtually at full capacity. How long had they been hanging around on the hook in the store? Or anywhere else, for that matter. Perhaps months, rather than weeks; or longer. All testing carried out in a battery box, needless to say…

The TV remote batteries, in my experience, if you have to keep twiddling them, then one answer is to get the voltmeter out. You could find the 1.5V Alkaline cell down at around 1.2825V, or lower. This may be a big part of the reason, replace with a nice fresh one, at 1.6206V or maybe a little higher, and all is serene again. Store the old cell in the fridge and then use it in the clock. We have three which all run on old cells. A long treasured carriage clock has always used up old cells, keeps perfect time, without fail, and runs the battery down to 0.8V, when it stops. In goodness knows how many years the spring loaded battery holder has behaved itself impeccably. Time, as they say, is expensive! I’m doing my bit to redress the balance.

I’d say it’s most unlikely that anyone would advise a newcomer to use a battery box. As far as I’m aware, too, no new radio sets are supplied with boxes for the receiver batteries, at least in the UK. I really don’t think it can be much of a massive problem. However, I always pass on as much advice about batteries as I can. On a good day, and with the proper care and attention, batteries can be ultra reliable. Ignore them, and they can rise up out of nowhere and smite you in the nether regions before you can say “watts that?”. It seems to me you’ve never really had to look very far to find evidence of someone that's had a tussle with a battery. And lost!

Malcolm, Your comment about the micro corrosion was interesting. Back in the good old days when model aeroplane were glued together with balsa cement there were electrical circuits containing mechanical parts, such as contacts, where these contacts were closed for long periods of inactivity, it was sometimes arranged for a very low permanent current to flow, known as the ‘wetting’ current, to try and prevent this high resistance film developing; and sometimes the contact action when closing was a sliding or wiping movement, for the same reason.

And I’m sure you’re right about the lamp, that’s the reason for the long lead, so you can hold it. But perhaps we can substitute leds, they seem to be the all-brand-new shining light at the moment. They claim to be pretty tough, so I’m sure we can arrange a suitable little exercise to see if in fact they can live up to this claim. Now all that’s left is to find a way that we can extract some filthy lucre out of it, but that might be the most difficult manoeuvre of all!

PB

[Steve W-O]

Posted by Peter Beeney on 05/07/2011 23:23:49:

Maybe the Min of Ag understood all about farming, and nothing about batteries? He ought to read this thread….



PB

 

 

Actually, it was the Minister of Defence's reply to a question by the Minister of Agriculture., my mistake.

 

Looking back at the OPs original post, which I saw as a caution to check batteries, it doesn't seem like much has been added to the original post.

Lots of interesting discussion and opinions,but still the thing I have got out of it is not to trust commercially made packs without checking.

 

 

 

 

(if you search youtube for Wrex Tarr "The News" you could hear where my comment came from, but many people don't understand his humour, so it is not funny to them. He was a Rhodesian comedian just after UDI, taking the mickey out of everyone outside of Rhodesia)

Edited By Steve W-O on 06/07/2011 05:28:49

[Tony Smith 7]

Going back to some of the original discussions, would anyone disagree that buying tagged cells and soldering up your own pack was sensible? Maybe the best solution. If I'm reading the earlier comments correctly, some people aren't happy soldering direct to the battery.

 

Any recommended sources for tagged cells?

[Lee Smalley]

Tony yes thats prob the best way of doing it, if A. you have the equipment, and B. have the time.

I have neither so made up packs are the way to go for me, i just found it staggering that some supplies make packs in such a poor manner knowing full well the environment they are to be used in, and a quick check, is now completely and throughly recommended of all your new packs, and no we should not have to do it but........

[Malcolm Fisher]

For me, there is a problem with tagged cells where the tags are spot welded on to the cell terminals, and this also applies to welded packs. The weld consists of four very small points which are actually fused, leaving a bigger area between the tag and the terminal in which corrosion can build up. Tags also seem to be very thin, possibly stainless, steel - not the best of electrical conductors. Many stainless steels suffer from "weld decay" which IIRC is combatted by including a small percentage of niobium in the steel. The weld decay causes the welded components to come apart usually bringing some of the parent metal with the welded on bit - the decay occurs a little distance from the weld and is related to the temperature reached during the welding process .

I have just re-attached the originally spot welded handle to a stainless steel jug for a neighbour which had failed for this reason, replacing the spot welds with rivets - something you can't do with tags on the terminals of batteries.

Pete - I missed that point about the long lead and had assumed that the bulb would also be dropped - silly me...

Malcolm

[Peter Beeney]

Tony - Tagged cells are easily obtainable I believe, starting with Maplins, they do a variety of sizes, both nicads and metal hydrides. Then there are outfits such as Strikalite, they have some of the brand names such as Sanyo, which might be a personal choice for me, if I were going to continue with nickel cells. But I’ve always soldered direct onto the cell anyway, only because that was the way I started to do it. Also LiFe cells of course, two make up a rx pack, but you need a balance lead to which you can connect one of those tasty little menu-scrolling-through-the-individual-cell-voltage on-board monitors. Then you need a lead-out with the appropriate plug, the LMS might be able to help here. I often solder the lead straight on to the switch harness though, it only takes a couple of ticks to do.

Lee - I’ve long ceased to be surprised by what I see and hear about troublesome modelling batteries; and much other aeromodelling hardware, too; and as the hobby has become more popular so I guess the problem has become more acute. I, and others, have tried to raise the awareness for a long time, inasmuch as you need to personally satisfy yourself that items are fit for purpose, because as we’ve seen quite often they are not. I appreciate that we shouldn’t have to do this, but unfortunately that’s little consolation while we are shoving the remains of our pride and joy into a black sack. Understandably many modellers are not always that familiar with electric’s, or engines, or radios and such paraphernalia so any help and advice can only be a positive guidance. But it can also quite difficult to make contact with base… … sometimes it appears to need repeat attempts to raise that awareness…

A classic example, perhaps, of being ‘unfit for service’ is the battery/switch harness plug and socket. At the very least this should be a latched device, i.e. one that locks closed and then you physically have to lift a latch to release it. But they are not, and for years I’ve insisted that youngsters have tied these together, or used a suitable retainer to ensure security, whenever I’ve been teaching them to fly. But there are still instances where these pull apart, with the inevitable consequences. If they had always been the automatically latched type, just how many model totally out of control pile-ups would this simple action alone have prevented? …. I consider this to be a very basic, simple and essential requirement; but for reasons best known to itself I suspect the model industry considers otherwise.
I know it’s a completely different kettle of fish, but within the full sized aircraft industry I wonder just how many power leads, vital to the plane’s safety, are joined with non-latched connectors? Here, I reckon these may well be double latched, even!
The BMFA and CAA are keen to tell us that in some cases the same overall safety rules apply to both models and full size, such as in the ANOs 137 and 138 etc. …So why don’t the same overall safety principles equally apply?

Malcolm - Some good point about the tags. Certainly when you see the state of them sometimes they do not inspire confidence. However, I have to say, in all my mucking about with cells they’ve proved to be surprisingly little trouble. Maybe the packs don’t last long enough for any decay etc. to get going… It’s the internal gubbins that seems to fail. I have noticed, on the very odd occasion, that one cell in the bunch will fail at a relatively early age. This happened in a tx pack I was using as a buddy set-up, I replaced the cell, with one out of the recovered box actually, I never throw anything away, and the pack was then good for a long time, several years. Another thing that might be of interest, if I’m given a suspect pack and there is a little ding in one cell, old crash damage maybe, that cell is highly likely to be the culprit. So if you put a dent in a pack, over time that might be significant, and eventually cause the cell to go faulty.
But it is certainly a fact of life that even without being bashed about, some cells are a total failure! Starting from day one!

Happy Landings!

PB

[Tony Smith 7]

The BMFA and CAA are keen to tell us that in some cases the same overall safety rules apply to both models and full size, such as in the ANOs 137 and 138 etc. …So why don’t the same overall safety principles equally apply?

Its actually a bit odd if you do compare full size with modelling practice and regulation.

 

I wonder how many people are aware that it is perfectly legal to build and fly a full size powered aircraft that has no certification whatsoever? No airworthiness certification or inspection, and no codes for construction or fit out other than upper limits on empty weight, stall speed and wing loading. The aircraft must be registered and display compliant markings, and the pilot must have a valid licence. Look up "SSDR" for more information.

[Tony Smith 7]

Thanks for the "Strikalite" pointer. They have low self discharge tagged cells, which I haven't seen elsewhere.

[Steve Hargreaves - Moderator]

Strikalite seem interesting.....not the cheapest around though I have to say....

 

A slightly worrying picture from their website however.....

 

There doesn't seem to be much support for either positive or negative wires here...

[Lee Smalley]

yeah they are going to last five minutes in an IC model!!!

[Lee Smalley]

all the ones i have bought direct from vapex recently have been well made

 

vapextech

 

and price for a well made pack £7.00

 

bargin

 

 

[Peter Beeney]

Steve,

Well, you can easily inspect the quality of the construction of the pack first, when it’s in that condition, and then do your own wrapping job and support for the cable. Saves you having to cut the insulation off. At least you wouldn’t have to do that bit. Looks like they are also quite willing for anyone to inspect the said welding and soldering without fear or favour, which, after what we’ve seen so far, may be exemplary. So I’d say, all in all, that’s a plus!

But there’s something else odd about that pack, if it’s a receiver pack. It’s a 6 cell, 7.2V battery. Which means that if you use it with a normal radio you would have to use a 5V regulator. Which in turn means it would only last exactly as long, in terms of flying time, as a standard 4.8V, 4 cell battery. That’s using a linear reg., a switched mode device would be better but there would still be some losses. Maybe that pack is for a specialist application?

You could use a 6V regulator, which would up the efficiency a bit, but you’d still only get the same time, but compare that with a 5 cell, 6V pack and you are back to square one.

It would seem as though life is never quite straight forward. Although I can just about remember the time, but only just, when Friday night was just about as straight forward as it ever got. But Saturday night ran it a very close second! And Sunday night wasn’t half bad on many occasions!

PB