Convoy L6... XHP70 Beast!

LED Flashlights – General Info 26650 Flashlights
1841

Seems someone is confused, or more than one someone.

2 cells in series, as in the L6, keep the capacity of a single cell but double the voltage. So 2 5000mAh cells that have 4.2V each are now a single “battery” with 8.4V and 5000mAh capacity. Remember that individually these are cells, in any form of multiple… parallel or series, the combination is referred to as a battery.

If there are cells in parallel, as in the Courui D01, the mAh capacity is multiplied by the number of cells while the voltage stays the same. So 3 2500mAh 18650’s would be 7500mAh of capacity at 4.2V. This can also be seen in back-up power supplies where 4 18650’s are used to charge phones and the like, the parallel configuration allows for enough capacity to charge a phone or tablet multiple times.

mAh is still a necessary feature because as has been discussed at length, not all cells will deliver their rated mAh capacity and ALL cells will lose this capacity over time as they go through charge/discharge cycles. This is where the danger comes in with multiple cells in series, it’s necessary to maintain balance between them. An older cell that has lost capacity will try to balance off the newer higher capacity cell and cause it to overheat, wherein bad things happen.

The confusion probably comes in due to the fact that a light run on 2 cells is usually pulling half the amperage from the higher voltage battery, the buck driver reduces the voltage by half (roughly) to the emitter. This allows for longer run times so it might seem the capacity is up, but instead it’s the voltage being bucked down to the 3V emitter that causes the longer run time. There will be some losses due to the driver making heat out of some of the converted energy, no driver is 100% efficient. (none that I’ve ever heard of anyway)

I’ve seen a push towards wattage lately and find it odd, it’s really irrelevant as our lights are seldom current regulated and the current draw drops steadily throughout the life of the charge, so the wattage is a fleeting figure. Also the emitter doesn’t maintain a stable output as it goes through a heat cycle and gradual cool down with lesser current, so there are enough variables that to state a wattage is misleading. Wattage is also not an ANSI standard of measurement for flashlights, so again, irrelevant and misleading.

1842

I decided go with s70, but after gb shipping problem I try to replace the batteries to an L6 (they dont have s70 :cry: )

1843

Thankyou, I’ll go with L6 (if gb sent :laughing: ) :+1:

1844

DB custom, that is great knowledge and answers for sure why a buck driver is more efficient than a boost driver, but I the is the 102 and 103 stuff not the 101 stuff that needs to be said. On a very basic electricity level for a given load let’s say an XHP70 putting out 4000 lumens, Z, it needs a voltage of X and a current of Y. Since X and Y won’t change and you are still looking for Z, we need a driver to change what the battery provides to what the LED needs.

So let’s assume a 100% efficient driver so regardless of what you input it will always provide just what the LED wants. So if we want 4000 lumens from the LED we need to provide it a certain power. Since our driver is 100% efficient it doesn’t matter what combination of voltage and current we provide from the battery it takes to get there. So if we provide 3.7 volts we need a current of “b” to get there but if we provide the driver 7.4 volts we only need a b/2 to get there since we doubled the current.

So even though we have have a 10000mah battery compared to a 5000mah battery relative to the 5000mah battery the 10000mah battery has twice the current draw and thus the same run time.

Of course the real world doesn’t have 100% efficient drivers and that’s where your edeucation of boost vs buck drivers come in. But if you do not understand the above you certainly won’t understand what you are talking about.

1845

I thought I understood it until DB and x57 just wrote that. I always thought power = wattage (sort of) and that no matter what the voltage or current is and how they vary, that the driver would compensate and take what it needs. That’s basically all that I meant by wattage (power) I hope that it wasn’t taken differently. Not that the LED had a certain wattage as in incandescent lighting. Am I wrong in thinking that? Please write for the understanding of a noob, not as though one is discussing it with someone who has been into this for years. I’m trying to use knowledge that I gained 50 years ago and had all of that time to forget from disuse. Thanks!

1846

I’m still a newbie, but please no cosmetic changes to the L6! :cry: I’m still a long ways from being able to own one and love how it is with no attachment point! Don’t really need one :cowboy_hat_face: I think swapping the tube around already makes a good compromise for those who want it

1847

’hammer,

If nothing is changed you can add your own or not, as I did. If they add an attachment point, trust me on this, it’ll only be for the good. It’s not easy to find that switch in the dark by feel, and with gloves on in the frozen north it’ll be impossible. It either needs to hang switch up or be lit, but it needs to found. Or they could remove the “valleys” in the fins except where the valley leads to the switch. That would work to find the switch and also increase cooling a bit.

It’s a great light but it could use a few tweaks that folks in warm climates can’t think of because it’s out of their experience. An attachment point could be as simple as a hole in a cooling fin. You’d never notice it unless you need it.

1848

Dose not the tail cap switch turn the L6 on to giveth light?

1849

The 10,000mAh cell won’t likely have twice the current draw. High capacity cells very seldom can match the high discharge rates of smaller capacity chemistry’s.

A good example of that, real world, is the 3400mAh 18650’s. They won’t run a direct drive driver at similar current draw as a 2500mAh 35A or a 3000mAh 30Q. Until recently, there was no 3000mAh cell that could supply this kind of draw but the Samsung 30Q answered that and Efest followed suit with their own version.

The Buck driver in this Shooter 2X makes it unnecessary to have a high discharge cell and as such, a good name brand 3400mAh cell can be utilized for longer run times.

You also keep referring to a 3.7V cell, most Li-ion’s are virtually dead at that point.

1850

No, it doesn’t change modes and sometimes to dispatch a predator or even just to dodge a skunk more light is required than ones crystal ball has divined.

1851

At 3.7 volts a cell in good health is in a condition of ‘sleep’. :slight_smile:

1852

Today I built an XHP-70 direct drive light that pulls 10.4A from 2 Samsung 20R cells, making 5451 lumens out the front through a 35mm Khatod Optic. These are only 2000mAh cells, so they won’t last long at 10.4A which is probably a good thing. (12 minutes? Theoretically? lol) This is exactly the kind of light I like using 7 modes in, for power supply management as well as thermal controls.

Now, if I were using those 10,000mAh MegaFire’s… :wink:

1853

3.7V is approx 28% capacity and virtually useless for a flashlight, especially a direct drive flashlight. If you’re heading out into the night with cells at 3.7V, you’ll be back inside pdq…

1854

The tail cap dose NOT turn the light on? Did not ask about mode changes and dispatching predators, dodging a skunk or my divine crystal balls?

1855

I know you didn’t that’s why I ignored the question and answered what I wanted to.

Obviously it’s not an issue with the tail cap, but the mode switch.

1856

I was just joking, we humans are fortunate to go from sleep to proactive as compared to even a new lithium rechargeable at 3.7 volts. :slight_smile:

1857

3.7V in theory is 40% in terms of capacity, but when it comes to energy it’s another story… In lower modes 3.7v should still provide a decent runtime, around 200 lumens for 2 hours.

1858

Wattage = voltage x amperage. In our particular use, the emitter has a forward voltage requirement that goes up with current (amperage), so the “6V” XHP-70 takes considerably more than 6V at high amperage. And yes, the voltage requirement changes as the cell sags under load, as does the current the cell can supply. So as the Voltage sags, the Amperage decreases and the emitter runs more efficiently as it get’s the lowered power levels and consequently makes less heat. I love using mass amounts of copper to offset the thermal limits, allowing the emitter to run hard as long as possible. There are a lot of arguments about this. Which of course is what makes it all interesting. I use copper, lots of beautiful copper, and I make hot rods. To each his/her own.

Not sure where the idea comes from that voltage and current are fixed, we are using cells that drain and drain rapidly under high loads. EVERYTHING is a variable.

When I first got my lightbox it all became very clear, the output is in a constant state of change, in most cases, and it’s very easy to see the effect of voltage sag and heat impact. I’m not talking about the manufactured lights and their safe zone outputs, I’m talking about hot rods, overclocked emitters and direct drive drivers. I don’t allow a light to stay stock very long, if at all. And with over 300 cells on hand, the only time any of my cells ever sat at 3.6V was the day I got em, every one of the 300+ cells I have is charged up and ready to go at all times. Yes, over 160 lights on standby at any given time. And virtually every one of those making all the light it possibly can.

The XHP-70 is rated for what? 3A? And yet the L6 is delivering over 4A and running well at that level? It does pretty well at 6.3A too, fwiw. Double the current max as listed by Cree. And the one I built today is running over 10A. We like pushing limits here on BLF, the forward voltage takes care of itself, self limiting in a relationship to what the cells being put to use can deliver. Buck driver’s change that, boost drivers exploit it, direct drive drivers just let it all hang out. :wink:

I am notorious for my ability to totally forget or remember things out of context, so as usual, I could be totally or even marginally wrong. But I DO know that 2 cells side by side double capacity while maintaining voltage, 2 cells stacked double voltage while maintaining capacity. Straight up, simple basic battery building 101.

1859

According to my highly acclaimed cottonpickers chargers, 3.8V is 30, even 4.0V is 75.

Drop a cell in a direct drive light at 4.2V and measure output in a lightbox. Try it again with the cell at 3.7V. Lumens will be WAY down, sure, it’ll taper off and run a long time at campfire levels, if that’s what you desire. But I for one use Turbo 98% of the time, as things that go bump in the night don’t show up well at match level

And stating 3.7V makes 200 lumens for 2 hours is widely misleading. What emitter? What power bin? What tint bin? What cells? What ambient temperature? What is the charge history of the cells in question? Variables, too many variables…

1860

True, but the light does have mode memory, so you could always leave it on Turbo if you want something that can put max lumens on target ASAP, with a quick half-press of the tail switch.
That said, I agree that the side switch can be hard to locate in the dark. It would be the perfect candidate for an illuminated side switch, and/or a raised switch boot IMO. :beer: