All those things you listed are in reference to 4S correct? As they would not apply to 2S.
Recommending unprotected cells for the 2s makes sense as it will pull higher amps.
Well let me try to make it clearer. 2S has longer runtimes than 4S because of drooping voltage. 4S will pull more amps, and will try to maintain high amps til the end of the cells -- that's how I understand it.
4S doesn't help much at the turbo level, since it gets too hot in under 10 minutes now in 2S2P, probably less time in 4S.
4S would help in lower modes I would think. It's all these crazy trade-offs goin on. Sure, 4S with constantly held output levels is nice, just can't be done on high amps because of high temps. There probably is a magic level of output that can level an operating temperature. Not sure they can hit that mark though, and probably dependent on other factors of air temperature, air movement, being held in hand, etc.
Dunno, I could be mis-understanding things, but I see pros/cons. If you want a nice stable low and medium mode of operation for the full discharge of the cells, 4S should be better for sure.
I think you are mixing them up backwards. First off there is a big difference if it is a buck or linear driver. I will talk about a buck driver here although the same things apply to a linear driver, just to a much lesser extent.
2s has very little voltage overhead and thus voltage sag will cause output to drop rather quickly. 4S will never drop output till the cells are nearly empty with a buck driver.
Total runtime will be very close between the setups as the total watt hours is held in the cells is the same. The 2S will have a bit more losses to heat due to the amperage but that will be a small issue by comparison.
2S will pull twice the amps for a given output wattage. If the XHP70 is outputting ~50w then it is pretty simple to see this.
7v x 7 amps = 49W of power
14V x 3.5 amps = 49W of power
Higher voltage = less amps
From an eletrical standpoint 4S is the far superior setup in all cases assuming either a buck driver or that you run multiple LED’s in series to make use of the voltage. Higher voltage is simply better.
Thats why electrical lines run hundreds of thousands of volts over the mains and only step it down to 220v at the last minute. Lower voltage is less efficient.
Lol, you two kill me. I like fet based drivers because I usually push for max output but I’ve got two lights that have the same battery carriers that are set up 4s so to keep from having to change up the carriers I’m going to have to go with a buck driver. I plan on putting a XHP35 in one and a XHP50 in the other. It’s easy to mod a light with a fet and a 6v led set up but I’m finding it a little more difficult with a buck and a 12v setup. I know I probably can’t push the XHP35 over 2.5a but I have no clue on the XHP50.
I know all those basics of power, voltage, V=I*R, etc., but I don't buy buck drivers are always superior, not in the real world, not with real parts and costs in mind. Theoretical, yes, but practically, all buck drivers have loss's, boost drivers even more so.
The real issue is how efficient does power from the cells get to the LED(s). I more than understand high voltage has it's advantages, but having the technology to buck it down with 100% efficiency doesn't exist as far as I know of. I thought the loss's were in the 20% range. We've been working/struggling with expensive buck drivers for several years here. Myself and others have had our share of blowing up IOS and KD bucks at $20-$25 a pop. Hank finally gave up on them from losing money on them. Others did too, or they would not warrantee them.
2S2P should run with only two batteries, no? I’m about to go camping with it, and that’s the only way I can think of to check it until I come back home.
Oh, and I wasn’t asked which I preferred. I wish they had asked me. I’m thinking a new tailcap should be easy to make. I think I’m going to try making one. Unfortunately it won’t make the threads any smoother. I already see quite a bit of silver under the anodization. Later on I’ll try to take a look through a loupe and take some measurements to see if I can figure out how they could have machined those threads better. I really hope they’ll refine this light, and take the feedback here and avoid these mistakes on their upcoming “super” lights.
They told me it was 2 brackets swapped out converts it between 2S2P and 4S - maybe they will send or sell you them? I did run the light on a single pair of cells - I measured amps that way, I believe. Pretty sure the one driver handles both - it's a buck driver but performs as a linear in the 2S2P config - that's common - I've seen with other bucks.
I posted earlier they are now offering the 4S configured lights on their website.
here: http://haikelite.top/index.php/haikelite-mt07-buffalo-cree-xhp70-flashlight-4s.html
They say "full current regulation but less Runtime".
I'm assuming now most people would prefer the 4S configuration. I might have misled them a bit because I preferred the 2S2P, but thought I told them the 4S would be popular... Hhmm... I think they got more testing in on the 2S2P. They got runtime specs on the 2S2P, but not on the 4S.
Would haikelight be offering the buffalo in Smo reflectors and 4s 12v configuration?
A good thrower gotta have it smooth.
Still waiting for the beam shot comparison between Smo and lop reflectors.
not sure why but im starting to lose interest on this light now >.<
The XHP50 can handle FET drivers wide open.
The XHP35 can apparently handle FET drivers with the max duty limited to limit current but I have not had time to test it yet myself.
FET drivers are simple, cheap and robust. They are not the best drivers though, a good buck is far better but also many times the price and complexity.
It depends on your goals. If you goal is max power to the LED, then higher voltage will always win.
In the case of a FET driver you will get more power to the LED running an XHP70 @ 12v vs 6V due to less losses in the circuit. It will also be more efficient overall due to this (although a pretty small percentage but there none the less). In fact an FET driver at 12V could very well pop an XHP70 or overdrive it to the point of silly. There is also more voltage overhead to pull from so even higher amps can be seen
In the case of a buck driver running a 6V LED at 12V will by FAR have the higher output ability. Basically unlimited really as there is ample voltage overhead to pull from. What this means is not only that you could run the XHP70 at 15+ amps if you wanted, it could also maintain that output till the cells are basically empty.
Buck vs FET drivers are a completely different subject when it comes to driver efficiency (which is totally separate from LED efficiency).
SMO/4S/XHP35 HI --> Might be a possibility
Not aware if an SMO exists yet.
One recommendation to HaikeLite. From my point of view…
When you choose the reviewers, please ask them for a minimum of parameters and conditions of presentation.
Especially in this case, until now the beamshot is missing and eventually comparing with the competitors. I’m on a click from the purchase and waiting for details …
The next product knock on the door and the lost time for complete advertising/presentation is important.
Surely nothing against Tom! He spends a lot of time and effort in R&D in the forum and has a great review, but with a some details missing.
Well they did ask in the beginning what our preference was; XHP70 or XHP35 (HI). Minor changes and they can offer both. Seems like a win win to me.
I personally prefer the 2S2P set up my self. To me this setup makes more sense this style set up is good for direct drive i guess. Bucking a higher voltage will give less sag but for sure run times will suffer. Plus there is the issue of safety for a standard consumer. Buck drivers will also create more heat need more space to work.
I get it you are using more voltage instead of amperage to create the watts. Obviously TA knows more then me hes in the driver building business did you see my pics mi took TA of the driver form the MT03?
I’m sure someone will have beamshots up by the time I get my 4S MT03 & MT07, but I’ll make sure to prioritize areas where info is limited.
No, I definitely deserve some blame. Thought I'd get to it over the weekend but didn't happen. Another reviewer, mhanlen, I'm sure with beamshots is due in another week or two - see post #212 for his comments.
I rushed my review out in one night basically - first day I got it. Let me see if I can do at least something this evening. We got some rain here, but it's 10%-25% chance here so might be an opportunity. I've done some outdoor use, plus wallshot comparisons, but no pictures.
It's a tighter spill than a L6, but that's expected because of the deeper reflector, and no hash or cross in the center because of the OP. Mine is the CW, so I could compare against a CW L6 if that helps. Also have some dedicated throwers but they are not in the same class as a XHP70 thrower.
Really I have no vendetta or anything of that nature. There is simply a lot of misinformation floating around about cell setup born from years of 3V emitter use with FET based drivers.
Now that we are starting to move past these old times I think it is time to put some of those myths to rest.
I did see the pictures of the MT03 and it is a buck driver for sure, although how the buck driver is setup I do not know but I can assume some things.
Please note, I am not calling you out or picking on your personally at all with these next statements, I am simply using them as examples.
Myths about cell setup:
Myth: 4s1p will have less runtime then 2s2p
Truth: Both setups have exactly the same amount of stored energy (about 45-50 watt hours depending on cells used). The only variable is how bright the LED is / how much power you are feeding it. So in low mode it might last a few days but in turbo it could only last 30-40 minutes. Given equal brightness they will have exactly the same runtime (well technically the 2s2p will have slightly less due to higher losses in the circuit but not enough to really matter).
Myth: 2s is safer then 4s?
Truth: I honestly do not even know if this is what you were meaning? 2s vs 4s is exactly the same when it comes to safety, the chances of getting shocked by either is basically zero. If you are talking about the 4s ability to run at full power until empty, this light has thermal regulation anyways and it will knock the power down as it heats up anyways. So I honestly do not know what this comment was in reference to?
Myth: 4s will create more heat then 2s
Truth: 2s will actually cause more heat in the driver then 4s due to higher amperage and larger losses in the driver. Amps is what causes heat in the circut, voltage has very little effect on heat inside the circuit.
In these particular lights which use a buck driver and have thermal regulation there is no reason to not use the 4S, I stand by this. These lights will be limited not be the cell setup but by heat anyways and the thermal regulation will step the power down to the same level in either setup to maintain those temps.
The difference is that the 2s will start dropping below the highest maintainable temp due to voltage sag but the 4s will maintain it throughout the entire cell life.
If people see this as a bad thing, then why not simply turn the power level down to medium and get the same or longer runtime with the 4s setup?
No problem this is why i was asking. I am no driver expert. I can understand. I honestly do not use that many buck drivers i am more likely to use a boost then buck.
I though running 4 cells in a series would be more dangerous then 2 in a series. Just for the fact that you have so many cells in series and the batteries have to match and that kind of stuff?
I could be crazy but say for instance if you use a 12 volt XHP70 with the 4S setup and you use a 6 volt XHP70 for the 2S2P set up. Would they even out in a sense would this be more closely matched? Does it also make a differences how the LEDs are set up like if they are in parallel or series?
Wow my sentence structure was bad lol Maybe i should go to bed! Edited!