Tube is big design change, spring not
Shorter tube means losing cell compatibility, longer single spring not
Shortening the tube only addresses the shorter cell, lengthening the spring allows the longer cells to still be used albeit at a higher compression ratio. Shortening the tube also messes with design parameters of spacing, knurling, grooves, and so forth, as well as changing the key design goal of matching the size and shape of existing SRK lights.
Okay, here’s where my ignorance has got me. I thought the measurements from The Miller and djozz showed there was still room for longer cells, even with tube shortening and using the same springs as the prototype. I also thought that the tube shortening only required some easy changes in the machining program(s), and since this isn’t a production light (yet) it would be no big deal. Lastly, the design goals have changed throughout this process already a few times. I don’t know why keeping it longer so to match existing lights should be such a sacred thing. Even so, it’s already a tiny bit shorter than standard SRK clones, and subtracting a millimeter or two won’t make that much difference anyway.
But, thanks for the explanation. I’m good now. :+1:
A spring just one step beefier (length, wire thickness) will solve many things: it is longer and stiffer so it applies more pressure on the shortest cells, while still accomodating long cells, and it can handle a bit more current before collapsing so it will probably still work with just one cell in the Q8.
A shorter tube solves just: further compression on shortest cells so more force applied but not as much as stiffer springs, but protected GA’s will be squeezed to the max (but will still fit). Extra current handling requires the second spring.
Why were button tops chosen as the battery? Do they have a specific advantage in this application? I am getting more batteries with this needing 4 anyway so NBD, but I use flat tops for everything else. I bought flat tops previously because they seemed to be more universally compatible, but hey, I may be wrong on that as well.
Proto3 was supposed to be production sample, only a last check and then approvement for producing followed. As it turns out some issues are still to be solved, but it helps if the solution for those issues are easy and certain enough that we do not need yet another prototype for testing. A somewhat larger spring is a solution that I’m confident needs no further tesing, a shorter tube I would be less secure about.
I’m already a bit nervous about the last minute changes in Narsil (which were needed, so it was unavoidable) that is being tested by Tom and others in the latest prototype, but perhaps the time is quite short to extensively evaluate it before the light goes into production.
It has to do with the simple design of the battery compartment: 4 bateries parallel in a tube, with the head screwed down on top of them. The tops of the batteries therefore rotate against a brass ring while the head screws down and end up in a random place somewhere on that ring. A flat top requires a spring at that spot or at least a button connection, both interfere with the rotation movement.
Thanks. So is this a typical/isolated issue with parallel multi-cell lights or did I just not notice a ton of lights that require BTs?
It is typical for the ‘SRK’ type of lights, a whole range of cheap 4-cell lights in soda-can format that were all copied from an original budget light named Sky Ray King. Many other flashlight brands have 4-cell soda-can-style flashlights that use a different construction: batteries are loaded from the rear (with proper springs so flat tops can be used) with inside the tailcap a rotating battery contact board that is held in place aligned correctly with the batteries while the cap is screwed tight. This construction is somewhat less simple but has, apart from allowing flat tops, the added advantage that batteries can be arrangement in series if that is part of the design.
There are quite a few of those like djozz mentions that don’t use electronic polarity protection, instead they use a mechanical measure at the positive end that requires a button top cell. Nitecore loves doing this, as does Sunwayman. They put 2 little brass bars on either side of the contact such that a flat top won’t make contact, so if you put the cell in backwards it won’t touch the positive contact pad at the driver end. (A flat top won’t touch either, as the blocking bars hit the shoulder of the cell.)
The SupFire M6 is or has been a popular light, it also uses the brass ring style. I’ve had to repair some lights that an absent minded friend of mine loaded flat tops in these style lights (brass positive contact ring) and shorted out the carrier collapsing springs or frying the driver. He’s done this more than a few times. The SP03 can short fairly easily by using flat tops. As can a great many of the SRK clones.
I for one am entirely happy with whatever’s decided by our benevolent overlords
and any improvements suggested by djozz
+1
Different springs seems like good solution to me, but whatever the Team decides is fine by me.
Agree
There is no need to change the Q8 in any way since proto 3 was designed as last sample before going into production. Everything on the Q8 is tested and found ok except when running 20A on one cell over one spring (duh!) What has a negative effect on the spring, since the inner spring does not contact the battery, so what else would you expect?
Bigger springs therefore are the best solution to do that!
Just my 2 cents…
+2…. and a lot more, to what hank & kahs said…………
An older gentleman gave me some words of wisdom almost 40 years ago that stuck with me……. “If it ain’t broke, don’t ”fix” it.”
Well, as far as I can tell ; the host design of the Q8 certainly “ain’t broke”… by a long shot.
All this talk of shortening tube length, changing this. possibly changing that, etc., etc. is nothing more than unwarranted rhetoric.
- Djozz has said from the start of this that a different spring will solve the “problem”^.
I, and obviously at least a few more people; think he has enough sense to know what he is talking about. A different spring will fix the “problem”, ^ <span class=“change minor a warrants that discovery a just is it “problem”… a it call even can we if”>.
- As far as running the Q8 on one battery. It was never designed to run full tilt safely on one battery in the first place. IF it happens to, fine. BUT if it has to be run on a lower output level to be operated on one battery……… so what?
- And as far as battery length. Tom E has done extensive testing with a number of different batteries. He has listed the results in several different posts here in this thread. All the ones he tested fit and worked in the Q8 :+1:
So………. IF you want to make sure your batteries are going to fit……… get something he has tested. That is a nobrainer.
IF you come up with some odd ball or experimental cell that was left by an alien when he visited this planet and it does not fit…. that is just to bad………… don’t complain. 
Exactly. IMO the only change that might need to be done is to remove the useless secondary spring and put a note in with the light to not run it full bore with fewer than 4 cells. As someone previously wrote, if it’s an emergency, one probably isn’t going to run it on the highest output anyway with just one cell. IMO, there are much smaller lights that will do that better anyway. But if someone does need to run it that way for an emergency are they really going to give a rats rear end about the light? At that point it’s sacrificial to my way of thinking. A $40 light is a fairly inexpensive payment to save a life. Yes, that’s what I call an emergency.
If the required cells can’t be used in it, then why are folks buying the light? It’s not as though it’s a secret as to what to use. Everyone has been right up front about that many times.
But whatever the design team decides, I’m good with it. The change to Narsil, that was required; the springs? Just polishing the apple before taking the first big bite. Polish it or not, I’m good either way. If I don’t have 4 charged cells I have other lights I can use and a few that just use one cell, and the knowledge to not turn the Q8 up to mega turbo with one cell in it. Folks, some people can’t be saved from themselves no matter how much we try. At some point we need to understand that some people can’t be trusted with matches. Maybe design a safe match… one that can’t be lit? Anyway, I’m good with what the team decides, but I wouldn’t agonize over it or hurt the light as designed.
Personally, I’ve never bypassed a spring but I have a few lights that have spring bypasses in them. I think I can do it with my meager soldering skill. The light was designed to be modded, right?
If it it known that a situation might arise where a single cell could be required, do a relatively simple spring bypass and that will save the spring. Really only takes seconds to do. One could prolong the joy of modding the Q8 by taking some time with it and maybe drilling a hole through the pcb for the bypass wire to come through and contact the heavier trace on the back side, but that might be stretching it. (I’ll go further than that, of course, just because I love modding.)
[quote=SawMaster]
This is not quite true. By going to a longer spring we can accommodate all cell lengths due to it’s greater compression range.
Not true again. One or more springs can sag just over time. It’s normal for a spring to loose a little of it’s free height after being compressed for long periods. So only using 4 unprotected cells over time may cause 1 or more springs to sag and eventually you will get some batteries not making contact or intermittent contact. This is the dangerous situation that I mentioned. You could have 3 cells with very light spring pressure against them and one cell that is not making contact. Three cells drain down while one stays charged fully. Then it may make contact and then the fully charged cell will start feeding the lower charged cells and it makes for a very bad situation. This is why we want to increase the spring tension on the very shortest cells. To give them some leeway to account for sag and still have decent spring pressure.
This whole issue with adjusting the springs/battery tube length has only to do with very short cells. This is what we want to get corrected. On the other end of things, we are hoping to not loose use of long cells. Long cell limitations, like 70.2mm max, may come into play, but it is a secondary goal to getting the short cells working just right.
I believe The Miller suggested a longer spring and gave dimensions for it. I was using his information. Here it is, the spring from the Thorfire S70.
One or more springs can sag just over time. It’s normal for a spring to loose a little of it’s free height after being compressed for long periods. So only using 4 unprotected cells over time may cause 1 or more springs to sag and eventually you will get some batteries not making contact or intermittent contact. This is the dangerous situation that I mentioned. You could have 3 cells with very light spring pressure against them and one cell that is not making contact. Three cells drain down while one stays charged fully. Then it may make contact and then the fully charged cell will start feeding the lower charged cells and it makes for a very bad situation. This is why we want to increase the spring tension on the very shortest cells. To give them some leeway to account for sag and still have decent spring pressure.
Certain small wire springs that are very cone shaped can collapse all the way flat, but most do not. If the cone is not tapered enough it will coil bind. If the coil wire is too thick it will coil bind. The springs we are talking about here are pretty big and long and do not compress fully flat.
Yes well we just wait on Thorfire to respond now
Funny all this talk of long cells, I just turned on the Nitecore TM06S on high, then inserted 1 protected Brinyte Panasonic with build in charging in the Q8, stepped outside, and ramped up till the output of the Q8 lighted as far as the TM06S (with its CW tint)
Now that was just plain awesome, the Nitecore became hotter and hotter and the Q8 just did not go beyond warm. And well despite it not doing max output, I really got a kick seeing so much light coming from a single cell that has not be designed for high drain applications.
A longer spring will have more range of travel from it’s fully extended height down to it’s fully compressed height. This longer range of travel has many benefits if the battery tube is also adjusted in length just right. We get more spring pressure on the shortest cells (which we need, as currently they don’t have enough pressure on them to account for future spring sag) as well as still being able to use long protected cells.