You use the free height and the compressed height to then get the battery range you want.
According to your earlier measurements, the current spring compressed height is 3.2mm and the max battery length is 71.7mm.
If this new taller spring has a compressed height of say 4.7mm, then we could just fit a cell length of 70.2mm and the battery tube length could stay the same. This should cover the majority of protected cells.
Then the extra free height of the new spring goes into compressing the shorter batteries more. This is good because currently they are not compressed very well.
Solder blobs are extremely strong. I would never imagine one coming off. The battery is going to be pressed up against the brass ring by fairly high spring pressure. Polishing the ring might help to eliminate the drag, but all it takes is a tiny snag and the edge of that cap will likely slice through the thin wrapper. I could be wrong. The edge of the button top might be fairly dull and wrapper might be crazy strong and it would never sliced through. I just can’t say for sure, but I would not trust it over time. A solder blob I trust.
I don’t know about FastTech and where they get their batteries from. Those tack welding machines are fairly cheap, like $200 for an entry level one, so it’s possible FastTech could add them plus a new wrapper themselves, but they sell so many that I would imagine they buy them from a middle man that can turn out large quantities.
If we go with a single slightly bigger spring (the tests show even the current spring delivers and the smaller of the pairs do not engage with the highest amp cells so there is not a real reason to keep a double spring setup IMHO) to avoid sagging, it only need to be able to be compressed to 4.23mm to allow even those ells with build in charging, this is a full mm, almost 25% higher then the currcnt big spring of the pairs.
Back on topic, the current springs allow a max battery length of 71.7mm. So all cells longer than that are currently excluded.
If we switch to a spring with a 1.5mm taller compressed height (from 3.2 to 4.7) and leave the battery tube the same, then the new max battery length will be 1.5mm less. Hence the new 70.2mm max battery length.
I was a bit late to the party, but to my understanding you have run 3 prototypes and now have a working light that performs well with most cells the testers have on Proto #3 with the dual springs right?
There is a concern that running high output from one cell you are putting high load through a single spring that risks its integrity then causes problems if it deforms. This is a unique problem to trying to drive four Emitors from a single high output cell such as a VTC6 or 30Q cell that can deliver 20A or more in this configuration through a single spring, probably for a very short time.
Now if your designing a single cell light (Astrolux S41/S42 etc) with 4 emitors and one cell, you would have an issue and should be concerned.
Last time I checked this is a quad cell light that is designed to be used with four cells, I think your design concerns should be focused on the requirements of a 4 cell light running on 4 cells, if the current prototype works well with most cells I would observe that going back to the drawing board and having to create yet more prototypes at this stage may not be the best way forward. The current springs do not appear to deform when loaded with four cells where all four springs are sharing the combined current of the emitors.
Finally, as you look at the world around you, you will realise its more important than ever that democracy and people’s opinion counts. If your concerned about either shipping something some people may not be happy with, or causing a delay that others may not be happy with - why not run a vote?
(P.S. I think those concerned with outright lumens number using more exotic spring material or spring bypass may be best served by modifying their lights once received, these objectives are had to obtain on a mass production scale would be my comment, and you are already seeing massive output with the prototype #3 and the springs you have.)
I honestly don’t think Thorfire would have any problems adjusting the battery tube length if that was needed.
It seems to be cnc machined from a solid chunk. All TF has to do is change a few dimensions in the cutting program. The area right below the threads seems a good spot to add or remove some length.
It’s probably not needed, but I wouldn’t be afraid to ask them should the need arise.
Tube is good, knurling above and below the flat is in nice balance in terms of looks and the size accommodates all sizes cells (it can even be used aligned, a rarity and of course I do not know if this works on the other protos and production)
Not quite. The issue is that short cells, which most people will use, are only getting a small amount of spring compression on them. All it takes is for one spring to get a bit weak, either through over heating or time itself, and you end up with it not making good contact. This creates a dangerous situation and needs to be addressed.
We just need a bit more compression on the short batteries to compensate for any sagging that may occur.
I doubt another prototype would be needed. If we can get a slightly longer spring, 2mm for instance, then it should work just fine and give us the safety margin we need.
With all these discussion on tube lengths and springs, I wonder at what stage is Thorfire’s mass production of the tubes at (if at all started) and have they purchased all the springs already.
…and here’s the point I made earlier: Thorfire most likely hasn’t begun production of the tubes. At the same time they most likely have bought the springs already. They’ve definitely built a few lights with the springs we see here, which indicates that assembly instructions are there, at least in some form. What this all means is that the cheapest, safest, easiest option on their side is to shorten the tube. All it takes is a small change in the dimensions given to the CNC machine. This will also save material, which may end up giving them more tubes for the same amount of material. “A penny saved is a penny earned.”
Still we go for the solution of a bigger and stiffer spring first. This does not require altering the battery tube length, it allows more battery length range, and the stiffer spring will make the light less sensitive to mode changes caused by bumps against the light. Thorfire has inquired what improvements a new spring should have and we try to communicate it as well as we can. Miller has sent my picture of how my bigger springs look like compared to theirs, and also in words we asked for somewhat bigger and stiffer, and not that much is needed at all to make it work well, while too long and stiff is also not ideal because that will make the light difficult to close, with a lot of wear on the threads.
The inner springs were not needed as they weren’t engaging while the light was producing the results we were seeking. Bigger springs will be better than the current big springs if all goes well and the small springs would be extraneous.
None of the battery manufacturers make button top cells or add protection circuits. It’s all done by third party. The button caps are spot welded on, like the tabs in battery packs.
You don’t need to order batteries from Fasttech if you are from the US. There are many sellers in the US selling every major brand at roughly the same price. The only difference being, you get them in 3 days, instead of waiting a month from China to save 2 dollars.
I think this is the best approach. Good contact must always be maintained between any cell and the spring(s) or it cannot deliver the potential amperage and that spot will heat up, potentially damaging the spring(s) making the situation worse . One or many springs is equally OK as long as the design works well. Those who want perfection can and will do a spring bypass out of habit; nobody else will notice a few missing lumens because the spring(s) can’t carry the full potential current available. If you stay with multiple springs just make sure they work properly.
Ar this point we should think back to the reason we wanted double springs: To carry more current. We’ve maxxed out the current now in the design. If one spring is very nearly as capable as two, then losing the second spring only makes the Q8 cheaper and easier to build which TF will like and which won’t really adversly affect anyone to any great degree.
[qoute] too long and stiff is also not ideal because that will make the light difficult to close, with a lot of wear on the threads.
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The good thread design you’ve got now will help with that, moreso if they are kept lubed (which should also be mentioned in the instruction manual). Spring pressure X4 can be considerable. If ypu think the failure modes through to the end, one bad spring gives poor performance which a muggle won’t understand and fix; they will just keep using the light as things get progressively worse, which is bound to happen if the springs fail first. Thread wear OTOH is apparent to everyone as to cause and effect, and given the good thread design should be far away before it happens. Ut will not affect the function of the Q8 until it pops apart, so the light performs perfectly until the end of it’s usable lifetime with the end giving you a warning (loose threads) before it happens. In the long term, something in this and every other design will fail from wear and tear first . The threads are beefier than the springs and there is an easy way to help them last longer (lube) whereas weakening springs can’t be so easily mitigated.
Yes, I do understand that fully. As I noted, no one design accommodates all cells, and the problem being discussed here happens only when too few cells are used in which case protected cells will no longer give the desired performance. I just think it more important the we do not lose any usability with shorter recommended cells. If both goals can be accommodated then good.
We’ve got great folks designing this light both in and not in the Q8 team, and the team is hearing us outsiders well, so in the end I have full confidence that the best solution will be found and implemented. It will not please everybody- no design can do that . As long as it is always kept in mind that this light is about high performance at an economy price, then the highest possible number of people will be happy with it, and that is a commendable goal which we’ve seen is being well targeted and well hit. In a world where we’ve seen nearly every GB light have some shortcomings, I’ve seen none here. Goals are being exceeded, not just met. It will happen with the spring and cell compatibility issues too.
I’m still somewhat baffled Jason, at the dimensions you provide for the theoretical longer spring. Where did you come up with the max compression number? I’ve looked at spring companies a lot in the past and they typically have quite a selection of flat max compression springs that collapse into themselves, limited only by the thickness of the wire used.
And losing one spring isn’t a dangerous situation even if using one cell, simply drop the cell in the next bay and carry on, it’s weaker now and won’t compress the spring due to heat like it did the first time, emergency situation still lighted.
Okay, I hate to be a bother, but I also hate not understanding something. So, I gotta ask: What advantage has lengthening the springs vs. shortening the tube? Why is it just so obvious to everyone that lengthening the springs is the best way to fix the issue? I just don’t get it! What am I missing? :person_facepalming:
