If there is an extra spring, it should be useful.
It doesn’t make any sense that the smaller inner spring won’t make contact with the battery when the larger spring is pressed, in that case, just leave the smaller inner spring and replace the larger spring by a thicker one.
I agree with Jos, it is best to change the smaller inner spring with a larger one, and keep the current larger spring ‘as is’ so both springs have good contact with the battery, so an individual spring can handle a higher current and reduces the resistance as well.
:+1: I totaly agree. Pushing the LEDs up to 80% right in the sweet spot is perfect (heat production to light output ratio). It protects the LEDs , gives more runtime and it makes the light save to use for almoste everyone. And the ones that want to push it further will definitely bypass the springs anyway
Sorry, haven't had much time as of late, but I plan on doing this mod to be able to accurately measure amps in the round 3 Q8, same as done to the first prototype:
I agree - my vote would be to raise the height/size of the inner spring to at or near the height of the outer, and possibly use a higher outer spring, not much higher though. I don't think they could reliably source better quality springs. Again, the conductance of the spring is dependent on the coating, not the spring steel itself. Thicker steel only means more stiffness. Granted most likely thicker springs will also have thicker coatings.
Sorry - I should have picked up on this and noted it for the round 2 prototypes - they had the same spring setup, though can't be sure the dimensions were matching. I suspected the springs might be a bit short, but with the variety of protected cells I tested of varying lengths, I would be concerned making it more difficult than already is. I suspect even though the short springs are not making top contact and compressing, they are still contacting the outer springs, thus reducing the resistance somewhat. The longest loops of the springs are at the bottom, so where ever the inner spring contacts the outer springs, it increases the flow, reducing resistance. I would not assume just because the top of the inner spring is not making contact, it's having no effect. I believe this explains why we still get pretty high output readings on short cells.
With classic single springs and FET based drivers, it's easy to demonstrate how more compression results in more amps - I've done this dozens of times. It's also true that amps go up initially with bare springs - I've seen this dozens of times, I assume it's heat related. When you bypass the spring, the rise in amps goes away, but of course you get a lot more amps with the bypass in place.
Tom, is it confirmed that the conductance of steel springs is for the greater part caused by the coating? I ask this because steel is a metal and will be conductant (though way worse than copper), and the percentage of any coating in the cross section of spring wire will be very small, I guess in the order of 1% or less? Or is it much more than that?
I repeatedly have bent the top of springs with pliers to open up space for a bypass. In doing so, on the cheaper springs, the coating comes off at times. I've tested the underlying steel for conductivity with a DMM and got no reading. I end up using the spring, but be sure I solder to a coated surface that's closer to the bottom end. I've been searching and searching and thought there was some info on this in an old thread here on BLF but can't find it. Coating thickness and specs on coating materials used is somewhat sketchy to find listed for springs. Gold plating is the best, but hard to find. Hank of course claims this here: http://intl-outdoor.com/gold-plated-springs-for-drivers-and-switches-20pcs-p-866.html, but he is one of the rare China sources I believe because I know he verifies this stuff personally and is a stickler for details and quality, plus a rare supplier of true quality beryllium copper springs, as you tested.
Ohh - electricity will seek the path of least resistance, so that's why it uses the coating of the springs, not the spring steel itself. Flashlight springs will always use a favorable conductive material for the coating layer, plus solderable of course.
Edit - also somewhere I saw tech data on how electricity travels thru solid copper wires, and I thought it was pointed out it mostly flows on the outer surface - there was some debate about hollow wires being as good as solid core because of that, but I don't think it was that simple. I'll try to find more references.
Oops - AC current travels more on the outer shell, DC is more evenly spread -- this is different though from coated spring steel.
A just-for-the-record answer on the tire analogy, just to satisfy the few who care…
A 2017 Corvette Grand Sport uses 285/30 19 tires on the front, 325/25 20 on the rear. That wheel choice severely limits what tires you buy. Not much either/or wiggle room left for the end user. (I didn’t even know they made a 25 series tire!) A quick search on Tire Rack shows me 2 selections, Continental Extreme Contact Sport or Michelin Pilot Super Sport. The Michelin rear tires are $483 each! before shipping and mounting. And according to my friend with the Camaro, these top of the line tires still won’t keep the car on the ground with the horsepower judiciously applied.
Sorry, no budget choices, period end of story. Sometimes that’s just the way it is. Pretty sure you can’t get by running a single tire…
Just because the light has 4 cells in parallel doesn’t mean it’s designed to run on a single cell. Obviously, there are cells that just won’t do it. A good many protected cells will cut out at the higher levels, not providing Turbo at any output level. It’s a Quad emitter light, it requires power.
Bout the spring coatings, I talked with my buddy here @work, a 30+ year design engineer, hobby rocketry, hobby ham (building and modding), etc... He said yes - spring steel is conductive and if coated properly, the steel should carry some of the current, but if the coating has better conductivity like gold, etc., it's kind of like putting 2 resistors in parallel - one high value, one low value, therefore more electricity will travel through the low value resistor - path of least resistance. From my experiences of not measuring conductance on the spring steel, it's probably a coating, whether a somewhat natural oxide coating or a non-conductive coating used to bond the outer coating layers. Now with the spring steel being thicker than the coating, yes - also helps if the electricity has a path to the steel, the thicker steel should help -- it's not just the coating. So I was somewhat right, somewhat wrong on this - least according to him. He also says obviously DC behaves different from AC, and also high voltage or high amps makes a difference in how it behaves.
I think there's tremendous variation out there with the quality of springs. The bonding, thickness, and type of materials of the coating are important and probably often overlooked. If there's a non-conductive coating on the steel for either bonding the outer coating layers or a developed oxide layer, then the spring steel isn't part of the conductance.
Thanks for the elaborate explanation on springs Tom
Dale you are right of course yet the Q8 works fine with one cell
Only using a single low drain cell with protection will cost the user the turbo mode.
And the thing is, if somebody wants to use it with 2 cells for a period of time and then wants to use four it should work just fine.
Don’t get me wrong, my tests did show it already does that but sagging springs are just not the kind of thing we would want and another slightly longer thicker spring should work just fine since Djozz and Tom both get nice high lumen on only the bigger of the two double springs now used.
This is the stage to address this for when production had started it will be a passed station.
I wish Nitecore would’ve asked before designing their TM03 the way they did. They took a Panasonic PF cell and ran 3 copper strips up the side to bring a protection circuit into it and also to take the ground contact to the top… this proprietary cell causes the light to need ground contact at the bottom, like all of our lights, as well as at the top outer ground ring. It also makes a relatively inexpensive Panasonic cell cost $20 at Nitecore. Crazy. I was able to remove a PF cell and rebuild it with a better cell but still… quite a tricky bit of work on that one and completely un-necessary. Locks you in to their proprietary cell only, with new cell chemistry and capacity coming out all the time it really dates this light that is otherwise a pretty decent find.
The better the Q8 is built from the get go, the longer it will be an iconic BLF figure…
At the bottom of the list it says to what post it is updated. Sorry if I missed it the last time and if you asked after the last list update I’ll do it next time
So I’m one of those annoying people who talked about running the Q8 on one or two cells.
I’m sure your technical analysis and car/tire analogy are all sound. But for a noob like me, I knew nothing about the performance penalty, and certainly wasn’t anticipating the issue with melting springs when running less than 4 cells.
Not coming from money, or wanting to spend too much on this hobby, that’s why some of us think of this from a monetary angle. If you spend $40 on a light, and have to fork over another $20 for batteries, it gives me pause. If a car costs $50,000 to buy, I’m not sure about you, but I would hesitate to spend $25,000 on tires for it.
But I’m in a very small minority here, so please don’t make any late changes on account of us. Do what’s appropriate for the majority. All I want to do is explain why some of us think the way we do.
Enelooper, if the one-cell requirement is dropped, the reason will be that it is too difficult to achieve, I and certainly Miller still find it a neat idea if the Q8 can run on one cell. We will see what Thorfire can do about the springs.
You can run it on fewer batteries but it would be silly to think there would not be disadvantages to doing so. The melting of springs can be mitigated with a spring bypass.
The loss in output and runtime can not be fixed, you simply have 1/4 of the power available, obviously you will have less power out the front of the light as well.
You can also get some cheap laptop cells to use in this light if you want as well. You can get a battery pack for around $10-15 generally if you look around and that usually gives you 6 cells. Won’t give you top performance but a lot better then a single cell.
LOL, this is very true. For many years before HP started selling printers with the “low capacity” toner in the box I would simply buy a new printer every time the toner ran out. It was cheaper to buy the whole printer then just the toner.
I would then sell the old printer and would generally end up paying less then $50 for over $200 worth of toner.
Guys, thanks for chiming in. While I really shouldn’t try to speak for others thinking about running on 1 or 2 cells, it’s really no big deal for me. I’ll still get the light, and I’ll make it work for me.
Texas_Ace: I was somehow led to believe that the only disadvantage of running one cell in a 4P setting is 1/4 the capacity of 4 cells. Didn’t realize there’s other issues as well.
I have laptop pulls, but they’re all flat tops. I don’t solder and I heard bad stuff if using magnets and the magnets shift inside the tube.
