I’m finding burrs in the grooves. Threads could be better. With some minor improvements, this could be a great light. Start with a slightly longer battery tube, smoother threads, and either sharper tools or more deburring. You could sand blast more, but I think that will reduce thread quality. Maybe an acid dip?
I don’t care much about 2s or 4s, but that choice is probably going to cause lost sales. 4s is probably the better choice though.
I’d like to see a holster accessory. A kydex holster that puts the light in the head down position is my preference.
4S does true buck regulation, 2S2P doesn't. So 4S gives you amp regulation - this is what I was told at least, and I've seen other buck drivers behave like this as well.
I would expect 4S to have flat, constant output instead of slowly trailing off like Tom detailed in his 2S2P review. The trailing off deal might actually be preferable to some as you’ll get longer run times and shouldn’t be able to see the slowly decreasing output unless you measure it.
I chose 2S2P because mostly think'n on upgrading to my own FET based driver. Dunno all the details but I don't mind voltage sag - longer runtimes, no sudden loss of output, no pulling high amps out of almost drained cells. Think all these things were said before...
Also they said protected cells are best with 4S, unprotected best with 2S2P. Hope protected cells can fit in the 4S light...
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.
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.
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).