Convoy C8+ New look for an old favorite

143 posts / 0 new
Last post
Lightbringer
Lightbringer's picture
Offline
Last seen: 4 hours 22 min ago
Joined: 08/30/2016 - 14:12
Posts: 6091
Location: nyc
mortuus wrote:
Cant they bump up the lumens atleast? like the astrolux version that does 1300 or so.. since it has more cooling fins it shouldnt be an issue? I mean since the name is c8+ the + to me should be an increase in lumens and throw also no ?

Nah, just use a ’70 so you get a big ‘+’ in the middle of the hotspot. LOL

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

Not a lot of point in trying to use a Boost driver with the XHP-35 in a single 18650 light as the same lumens and essentially the same beam can be had with a well driven XP-L HI. Similar amperage will be drawn from the cell in both cases, so there’s no real gain to go with a boosted 12V emitter. Just a more complicated driver that costs more.

Dale

WalkIntoTheLight
Offline
Last seen: 12 hours 52 min ago
Joined: 12/05/2015 - 10:26
Posts: 1552
Location: Canada
DB Custom wrote:
Not a lot of point in trying to use a Boost driver with the XHP-35 in a single 18650 light as the same lumens and essentially the same beam can be had with a well driven XP-L HI. Similar amperage will be drawn from the cell in both cases, so there’s no real gain to go with a boosted 12V emitter. Just a more complicated driver that costs more.

That’s a fair point if you use the light only in maximum, which is probably what most people do with a C8. I was thinking of more efficient modes other than max, but I suppose that’s something more applicable to a light like the BLF A6. I think the XHP35 is supposed to be brighter and more efficient than the XP-L, but perhaps not worth the extra expense of a boost driver in a budget light.

Still, it would be nice to know what a C8 with an XHP35 HI would cost, before giving up on it.

BobbyMK
BobbyMK's picture
Offline
Last seen: 4 hours 32 min ago
Joined: 09/10/2015 - 05:50
Posts: 333
Location: Macedonia

https://www.aliexpress.com/item/Desert-tan-convoy-C8-host-not-include-LE...

Host version available, i got one.

Although i like the new improved design i think that C8+ should have been 20% beefier than the standard C8 and run of 20700/21700 battery. Would be sweet spot for everything.

 Olight i3s, Olight S1, Olight S Mini, JetBeam Jet-1, BLF 348, Astrolux S41S, UF SK-98, Convoy S2+ 3*XP-G2, Convoy S2+ 3*XPL, Convoy S2+ 219CT, Convoy M1, Convoy C8, Brinyte B158, Courui D01, Convoy L6, Noctigon M43

mortuus
mortuus's picture
Offline
Last seen: 2 hours 41 min ago
Joined: 12/16/2014 - 09:33
Posts: 1103
Location: Sweden

BobbyMK wrote:
https://www.aliexpress.com/item/Desert-tan-convoy-C8-host-not-include-LE...

Host version available, i got one.

Although i like the new improved design i think that C8+ should have been 20% beefier than the standard C8 and run of 20700/21700 battery. Would be sweet spot for everything.

I agree it should have a little more lumens and take bigger batteries wouldnt hurt but i guess since convoy is about budget u cant expect that perhaps idk but then again whats the point calling it + if just the host changed? not much need imo. i have 2 c8 already.

...where Frugal meets with Flashlight!

ZozzV6
ZozzV6's picture
Offline
Last seen: 2 hours 15 min ago
Joined: 03/24/2016 - 12:19
Posts: 1866
Location: Near to my soldering iron.

J-dub:
Can Simon make the led shelf thicker? In the old C8 it was only 2mm thick. Nowadays many of us put SST40 leds and fet drivers in these hosts and I will be happier if it will have a 4mm thick shelf. It doesn’t really a big change and it is not even make the machining time longer. It even make it shorter as you need to remove less material from driver side.
The old shelf can handle well the stock 2,8A current but with 6-8A it will be better with more mass. Also like the 21700 battery idea.

beam0
beam0's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 12/20/2011 - 23:18
Posts: 3195
Location: Pennsylvania

WalkIntoTheLight wrote:

……………………………………………it would be nice to know what a C8 with an XHP35 HI would cost, before giving up on it.

I’m thinking maybe around $30?

http://www.kaidomain.com/p/S027411.KDLITKER-C8_2-Cree-XHP35-HI-Neutral-W...

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

WalkIntoTheLight
Offline
Last seen: 12 hours 52 min ago
Joined: 12/05/2015 - 10:26
Posts: 1552
Location: Canada

beam0 wrote:
WalkIntoTheLight wrote:

……………………………………………it would be nice to know what a C8 with an XHP35 HI would cost, before giving up on it.

I’m thinking maybe around $30?

http://www.kaidomain.com/p/S027411.KDLITKER-C8_2-Cree-XHP35-HI-Neutral-W...

Nice! I wonder if that is really 2000 lumens, or somewhat exaggerated. Anyone know?

If it’s putting 1500mA into that LED, it might be 2000 lumens.

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

If that’s the light I think it is my buddy in H town got one and it was quite a bit short of the advertised lumens.

Edit: With the 12V emitter a single cell has to be boosted 3x and then some, so if the limit is 1500mA then the 35 isn’t going to do all that much more lumens than a well driven XP-L HI. Current overall will end up very comparable.

Dale

WalkIntoTheLight
Offline
Last seen: 12 hours 52 min ago
Joined: 12/05/2015 - 10:26
Posts: 1552
Location: Canada

DB Custom wrote:
If that’s the light I think it is my buddy in H town got one and it was quite a bit short of the advertised lumens.

Edit: With the 12V emitter a single cell has to be boosted 3x and then some, so if the limit is 1500mA then the 35 isn’t going to do all that much more lumens than a well driven XP-L HI. Current overall will end up very comparable.

1500mA is overdriving the 12v XHP35, but it should be do-able with good heat-sinking. The XHP35 is more efficient than an XP-L. It might produce 2000 lumens at that current, but I’m not sure. The XHP35 HI, perhaps not.

But, yeah, specs are often over-stated, so 2000 lumens has me suspicious.

beam0
beam0's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 12/20/2011 - 23:18
Posts: 3195
Location: Pennsylvania
DB Custom wrote:
Not a lot of point in trying to use a Boost driver with the XHP-35 in a single 18650 light as the same lumens and essentially the same beam can be had with a well driven XP-L HI. Similar amperage will be drawn from the cell in both cases, so there’s no real gain to go with a boosted 12V emitter. Just a more complicated driver that costs more.

I thought the XHP35 HI had a slightly different beam (a bit more spill) than XP-L HI?

I also thought it used less current than XP-L HI to produce similar output, in other words I thought an XP-L HI had to be driven harder to produce the same output as an XHP35 HI, and thus XHP35 HI is more efficient?

Looking at these (Mfg. Specs) below there isn’t much difference in output/throw. Is there any reason to use an XHP35 HI at all? Why is Thrunite and Utorch using it for their single cell throwers instead of XP-L HI?

Emisar D1S………..18650………..XPL-HI…………1300lm…………..720m
Maeerxu M8………..26650……….XPL-HI…………1200lm…………..800m
Utorch UT02……….26650……….XHP-35 HI……..1300lm…………..700m
Catapault V6……….26650……….XHP-35 HI……..1700lm…………..750m

I need to learn about this because I had been planning on modding a single cell light with XHP35 HI instead of XP-L HI because I understood it would have slightly more spill and slightly higher lumen output, using less current from the cell.

.
The efficiency I was basing from the Cree specs:

Cree Data:

XP-L High
Maximum Drive Current……..3 A
Max Power (W)………………10 W
Max Light Output…………….1095 lm

XHP35 High
Maximum Drive Current…….1.05 A
Max Power (W)………………13 W
Max Light Output…………….1483 lm

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

The XHP-35 can make around 2500-2600 lumens at 2.5A-2.8A, will burn up somewhere North of 3A usually. Anything over 2.5A or so is typically just making more heat without making noticeably more lumens.

The XP-L HI can do around 6.5-6.7A and make up to 1700-1800 lumens. It’s forward Voltage will limit it on a single cell so that it will not burn up.

So if you look at what the single cell from a boost driver is actually being asked to provide, the current from the cell is upwards of 4.5A or more, the driver itself producing heat to go along with the pushed emitter. You’re really not gaining much going 12V XHP-35 on a single cell. That’s what I find in the lights I’ve looked at. Most boost drivers won’t push the 35 to 2.5A from a single cell, so it’s lumens is down around where the XP-L HI is, begins to look like a lot of work to get back to where we started…

Dale

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

Spec sheets? Do we use those here?

Dale

ZozzV6
ZozzV6's picture
Offline
Last seen: 2 hours 15 min ago
Joined: 03/24/2016 - 12:19
Posts: 1866
Location: Near to my soldering iron.

BeamO:
The UT02 putting out a pathetic 900 lumens in real world in stock. But the Emisar D1S putting out about 1500 lumens stock. See my measurement google tables. You will fi d various flashlights with a lot of led type and beamshots.

Agro
Online
Last seen: 19 sec ago
Joined: 05/14/2017 - 11:16
Posts: 2928
Location: Ślōnsk

XHP35 will rock once GXB172 or Shocki’s boost driver are out. Which can happen at any time…either close or far, they are a quarter late already.

beam0
beam0's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 12/20/2011 - 23:18
Posts: 3195
Location: Pennsylvania

DB Custom wrote:
The XHP-35 can make around 2500-2600 lumens at 2.5A-2.8A, will burn up somewhere North of 3A usually. Anything over 2.5A or so is typically just making more heat without making noticeably more lumens.
Thanks, so if I understand correctly this is current draw at the emitter not current draw from the cell? And when the emitter pulls this current, the boost driver is actually pulling nearly twice that from the cell?

.

DB Custom wrote:
Spec sheets? Do we use those here?
It was all I could find to see the numbers. Facepalm I guess I need to ignore those cree specs and look at real specs here like ZozzV6’s measurement tables.

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

beam0
beam0's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 12/20/2011 - 23:18
Posts: 3195
Location: Pennsylvania

ZozzV6 wrote:
BeamO:
The UT02 putting out a pathetic 900 lumens in real world in stock. But the Emisar D1S putting out about 1500 lumens stock. See my measurement google tables. You will fi d various flashlights with a lot of led type and beamshots.
Thanks I didn’t know! You’re tables are a great reference I should have been looking at.

It really looks like the SST40 dedomed comes out on top over both XHP35 HI and XP-L HI, so I have to also consider that emitter for my mod.

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

DavidEF
DavidEF's picture
Offline
Last seen: 7 hours 28 min ago
Joined: 06/05/2014 - 06:00
Posts: 6316
Location: Salisbury, North Carolina, USA

DB Custom wrote:
Spec sheets? Do we use those here?

I don’t. I use the CREE PCT. And what I find is that counting the LED only, the highest bin XHP-35 HI is more efficient than the highest bin XP-L HI along its entire rated range. The needed boost driver would have to be less efficient in order for the flashlight to end up less efficient. I thought it’s been said that a boost circuit is more efficient because it’s using the whole voltage output of the cell instead of burning up the voltage difference from the cell to the emitter like linear drivers do. But, I don’t know. Just going off what’s been said around here. I’m curious how real life differs from these widely held BLF beliefs. You mentioned heat, but I’m just looking at efficiency as power in, light out. Heat just makes up the difference in lost power.

Reason is not automatic. Those who deny it cannot be conquered by it. Do not count on them. Leave them alone.
-Ayn Rand

beam0
beam0's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 12/20/2011 - 23:18
Posts: 3195
Location: Pennsylvania

Agro wrote:
XHP35 will rock once GXB172 or Shocki’s boost driver are out. Which can happen at any time…either close or far, they are a quarter late already.
In reference to what Dale wrote (post #43 above) how will this new boost driver make the XHP-35 HI an advantage over a FET driven XP-L HI?

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

Does the PCT go to 2.5A for the XHP-35?

Does the PCT go to 6.6A for the XP-L HI?

If not, on either one, the efficiency numbers are skewed.

The boost driver is converting the ~4V of a single Li-ion cell to ~13V for the 12V rated emitter, so it’s more like 3x or a little more when the cell is fresh. When the cell is dying the driver is pulling even higher amperage to convert 3A to that same 13ish. So the boost driver will pull 5-6A on a fresh cell and up to 9A or more as it dies, that is of course if it’s a regulated boost.

Our FET Direct Drive drivers are very efficient at Turbo as they are virtually direct off the cell, again though we have to consider how far over rated max the emitter is being pushed to get an idea how much more heat it’s making and what that might be doing to the emitter and it’s output. The FET driver doesn’t make heat on it’s own, whereas the Boost circuit does. So that is added into the equation as well.

In the end, if a FET driver is used with an XP-L emitter (HI or otherwise) the output is close enough to the XHP-35 at reduced current levels (those the single cell boost drivers are capable of achieving) that it’s really a waste of money to go with the more complicated circuit.

The SST-40 from Luminus is another not very efficient driver, although it IS capable of 2600+ lumens and from a single cell with an FET driver, the downside to this one to date is the limited tint availability, only available in a blue-white cool tint so far. It’s capable of hitting the cell for 9.8A or so to make the big lumens, so yeah, there’s a lot of heat going on there as well.

Dale

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

Richard worked very hard to make a 17mm boost driver happen, but it just isn’t feasible at that size as it can’t make the 2.5A optimum current requirement for the XHP-35, get’s hot and acts wonky, ends up failing in the long run if pushed that hard. So it’s expensive, difficult to pull off, and the gain is a mere 500 or so lumens IF you can get it work. The XP-L2 is capable of 2300 lumens on the FET driver/single cell configuration so there go the XHP-35’s advantages…

Now, if you’re going to run 4 18650’s in series and Buck the current down to the XHP-35, then the lumens output makes it worthwhile and the throw stays high while adding in a larger hot spot. A clean de-domed XM-L2 will best the 35 in throw, with a considerable lumens disadvantage. So it’s again about compromise and trade-offs.

The UTorch UT02 lights are a good example, using a 26650 cell they still can’t get the driver to boost decent current to the 35 without overheating. They’re giving around 1300 lumens in stock form these days. I pulled the 35 and piggybacked an FET+1 With Anduril running an XP-L HI and am getting 1700 honest lumens for over 200Kcd throw, much mo bettah! Big Smile

Dale

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

Perhaps those new highly touted boost drivers are over a quarter late already for a reason? Wink

If we could run with a 22mm or 26mm driver, then larger and better components can be used and it might just work, the driver ends up in the $25 range instead of $5 or 6 but there it is, gotta pay to play.

Dale

DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

For the record beam0, I have an XP-L HI V3 3A running 6.4A and making 1538 lumens for 1.05Mcd…. from a single 32650 cell.

Yes, that’s 1,050,000 candela, as measured at 50M.

Dale

Agro
Online
Last seen: 19 sec ago
Joined: 05/14/2017 - 11:16
Posts: 2928
Location: Ślōnsk

beam0 wrote:
Agro wrote:
XHP35 will rock once GXB172 or Shocki’s boost driver are out. Which can happen at any time…either close or far, they are a quarter late already.
In reference to what Dale wrote (post #43 above) how will this new boost driver make the XHP-35 HI an advantage over a FET driven XP-L HI?

Much higher output, somewhat higher throw, much higher efficacy (lm/W). And fully regulated boost allowing it to get full output from half-discharged cell.
You pay for that with much lower throw-efficiency (cd/W), higher price, larger drivers and worse driver availability.
DB Custom wrote:
Richard worked very hard to make a 17mm boost driver happen, but it just isn’t feasible at that size as it can’t make the 2.5A optimum current requirement for the XHP-35, get’s hot and acts wonky, ends up failing in the long run if pushed that hard. So it’s expensive, difficult to pull off, and the gain is a mere 500 or so lumens IF you can get it work. The XP-L2 is capable of 2300 lumens on the FET driver/single cell configuration so there go the XHP-35’s advantages…

Come on, don’t compare XHP35 HI to XP-L2.
Lumens may be similar, but the latter has terrible tint and doesn’t throw.

BTW, I wouldn’t drive XHP35 to 2.5A in any of the hosts discussed in this topic. I’d rather do 2.1-2.3.

XHP35 is Pareto optimal in throw vs. output. And by a large margin. You can best it in either, but by sacrificing disproportionally lot of the latter. It is also quite efficient from medium currents up, has good tints and doesn’t require dedoming. They only drawback is that it’s 12V.
And I can’t stop thinking that with a larger package and better thermal path it would be even more awesome…

DB Custom wrote:
Perhaps those new highly touted boost drivers are over a quarter late already for a reason? Wink

If we could run with a 22mm or 26mm driver, then larger and better components can be used and it might just work, the driver ends up in the $25 range instead of $5 or 6 but there it is, gotta pay to play.

Maybe. I don’t know. Lone Oceans has shown his driver to output more power than XHP35 can take, so maybe not.
Anyway, I stopped holding my breath. Tired

Agro
Online
Last seen: 19 sec ago
Joined: 05/14/2017 - 11:16
Posts: 2928
Location: Ślōnsk

DB Custom wrote:
For the record beam0, I have an XP-L HI V3 3A running 6.4A and making 1538 lumens for 1.05Mcd…. from a single 32650 cell.

Yes, that’s 1,050,000 candela, as measured at 50M.


I didn’t think such currents were possible with XP-L HI and FET.
According to Texas Ace that’s over 4.08 Vf.
Did you win the Vf lottery or did Texas Ace lose it?

Anyway, that “higher throw” of XHP35 HI that I wrote above doesn’t seem right now. In a low resistance host, with a powerful cell XP-L HI might offer a bit better throw.

beam0
beam0's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 12/20/2011 - 23:18
Posts: 3195
Location: Pennsylvania

DB Custom wrote:
For the record beam0, I have an XP-L HI V3 3A running 6.4A and making 1538 lumens for 1.05Mcd…. from a single 32650 cell.

Yes, that’s 1,050,000 candela, as measured at 50M.

Wow over one million candela! I assume it has a jumbo size reflector?

Thanks for all the info and explanation, it was going to be considerable hassle and extra cost involved in trying to use the XHP35 HI, so I’m going to take your advice and keep it simple with an XP-L HI and FET driver.

Since you mentioned it, I remember now it was the larger hot spot (not more spill) that had my interest in the XHP35 HI, which would be nice. But even though I do have a 20mm driver space, after reading all this I see it’s still isn’t worth chasing after the 12V emitter. I’m happy this got sorted out before I ordered any parts.

I guess because there’s so many newer production lights using XHP35’s that had me thinking it was the better way to go. The XHP35 C8’s from Kai reportedly get hot quite fast compared to their XHP50.2 version C8’s, now I understand why.

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

WalkIntoTheLight
Offline
Last seen: 12 hours 52 min ago
Joined: 12/05/2015 - 10:26
Posts: 1552
Location: Canada
DB Custom wrote:
So if you look at what the single cell from a boost driver is actually being asked to provide, the current from the cell is upwards of 4.5A or more, the driver itself producing heat to go along with the pushed emitter. You’re really not gaining much going 12V XHP-35 on a single cell. That’s what I find in the lights I’ve looked at. Most boost drivers won’t push the 35 to 2.5A from a single cell, so it’s lumens is down around where the XP-L HI is, begins to look like a lot of work to get back to where we started…

My lights that use XHP35 HI put out about the same lumens as a FET-driven XP-L HI, but they can do it fully-regulated. My XP-L FET lights suck when the battery gets about 50% drained, whereas my boost-driver XHP35 lights still have their full output.

For example, my Zebralight that uses XHP35 HI will provide full maximum output until the battery voltage drops to about 2.9v, which is almost its entire capacity. Also, since I don’t think Zebralight overdrive’s it, it’s more efficient.

So, I think there are advantages to using an XHP35 HI with a boost driver, even if it’s not any brighter than a XP-L HI with a FET driver.

DavidEF
DavidEF's picture
Offline
Last seen: 7 hours 28 min ago
Joined: 06/05/2014 - 06:00
Posts: 6316
Location: Salisbury, North Carolina, USA
WalkIntoTheLight wrote:
DB Custom wrote:
So if you look at what the single cell from a boost driver is actually being asked to provide, the current from the cell is upwards of 4.5A or more, the driver itself producing heat to go along with the pushed emitter. You’re really not gaining much going 12V XHP-35 on a single cell. That’s what I find in the lights I’ve looked at. Most boost drivers won’t push the 35 to 2.5A from a single cell, so it’s lumens is down around where the XP-L HI is, begins to look like a lot of work to get back to where we started…

My lights that use XHP35 HI put out about the same lumens as a FET-driven XP-L HI, but they can do it fully-regulated. My XP-L FET lights suck when the battery gets about 50% drained, whereas my boost-driver XHP35 lights still have their full output.

For example, my Zebralight that uses XHP35 HI will provide full maximum output until the battery voltage drops to about 2.9v, which is almost its entire capacity. Also, since I don’t think Zebralight overdrive’s it, it’s more efficient.

So, I think there are advantages to using an XHP35 HI with a boost driver, even if it’s not any brighter than a XP-L HI with a FET driver.


That’s what I was thinking would be the case. I don’t have either in a light right now, so I can’t compare. But, I can’t imagine the XHP-35 HI would ever switch over from being more efficient than the XP-L HI to being less efficient than the XP-L HI just because you go past the CREE max current rating. Both of them will lose efficiency, but the XHP-35 HI should still always be the more efficient of the two.

Reason is not automatic. Those who deny it cannot be conquered by it. Do not count on them. Leave them alone.
-Ayn Rand

Agro
Online
Last seen: 19 sec ago
Joined: 05/14/2017 - 11:16
Posts: 2928
Location: Ślōnsk
DavidEF wrote:
WalkIntoTheLight wrote:
DB Custom wrote:
So if you look at what the single cell from a boost driver is actually being asked to provide, the current from the cell is upwards of 4.5A or more, the driver itself producing heat to go along with the pushed emitter. You’re really not gaining much going 12V XHP-35 on a single cell. That’s what I find in the lights I’ve looked at. Most boost drivers won’t push the 35 to 2.5A from a single cell, so it’s lumens is down around where the XP-L HI is, begins to look like a lot of work to get back to where we started…

My lights that use XHP35 HI put out about the same lumens as a FET-driven XP-L HI, but they can do it fully-regulated. My XP-L FET lights suck when the battery gets about 50% drained, whereas my boost-driver XHP35 lights still have their full output.

For example, my Zebralight that uses XHP35 HI will provide full maximum output until the battery voltage drops to about 2.9v, which is almost its entire capacity. Also, since I don’t think Zebralight overdrive’s it, it’s more efficient.

So, I think there are advantages to using an XHP35 HI with a boost driver, even if it’s not any brighter than a XP-L HI with a FET driver.


That’s what I was thinking would be the case. I don’t have either in a light right now, so I can’t compare. But, I can’t imagine the XHP-35 HI would ever switch over from being more efficient than the XP-L HI to being less efficient than the XP-L HI just because you go past the CREE max current rating. Both of them will lose efficiency, but the XHP-35 HI should still always be the more efficient of the two.

The emitter will be more efficient. But the emitter-driver combo?
At high current GXB172 is 90% efficient.
At high current FET driver is nearly 100% efficient.
Now, if we’re talking driving lights with a fresh powerful batteries (and that’s what most of this topic is about), XP-L HI V3 driven to mere 5A does 1500 lm with 80 lm/W.
XHP35 HI E2 is doing the same 1500 lm has 120 lm/W. Drop it by 10%, it’s still much better.
With higher currents the difference will be larger.
So with a weak or not-fully-charged cell XP-L HI may be more efficient. Or maybe not….
At high current….not really.
DB Custom
DB Custom's picture
Offline
Last seen: 6 hours 34 min ago
Joined: 01/13/2013 - 22:28
Posts: 18490
Location: Heart of Texas

beam0, you can use an XP-L HD (dome on) and get a larger hot spot if throw isn’t everything, which it really can’t be in a light the size of the C8 anyway.

I didn’t like the ringy beam profile in my ArmyTek Barracuda Pro with XHP-35 HI, for example. So I put an HD variant in it and it’s got a very nice beam profile now.

Zebralights are so cheap, think I’ll pick up a few of em and try em out…. (NOT!) Silly So yeah, regulated gives the full output level til the cell dies, but what does that do in the long run to the cell? And you get so little warning before it shuts down, at any rate, compromise rears it’s ugly head…

Put an XM-L2 U4 in the C8+, the lower forward Voltage will keep the FET from allowing too much current draw while it still gives out a lot of light, run time is longer, output is similar, large hot spot for a great general purpose light. Wink

(Edit,,, 114 lumens per watt vs 109 lumens per watt, are those few lumens difference really worth worrying about? You can’t see 50 lumens difference on the top end anyway.)
(Edit II,,, what makes the difference for me isn’t efficiency or sheer lumens, it’s the available UI. I can use the FET+1 and TK’s firmware and have a UI that can back up, not go through all the modes but reverse back down to lower modes and conserve the cell when Turbo isn’t needed. That ability, start on moon and long press for Turbo, that is the game changer as far as I am concerned and it’s why I don’t use a boost circuit… even why I use TK’s FET set-up in lights that came with a boost/35 to begin with.)

Dale

Pages