# Seoul P7 direct drive concern



## KrisP (Apr 24, 2008)

Hi,

I made a 3D Mag with a Seoul P7 CSW0I (Vf - 3.25v) that runs from 3 Tenergy D-size Ni-MH cells direct drive. I chose direct drive because so many people on here have said it's fine with Ni-MH cells. 
Anyway, I put in 3 cells I had laying around that were partially discharged and it ran fine. I measured that it was only drawing 1.8A so I decided to charge the cells... They've settled overnight and have a total voltage of 4.27v when measured direct to the cells (I know this isn't accurate with Ni-MH cells). I put the cells in the light and measured the numbers below, then put 3 other D cells that were partially discharged and measured again.

Freshly charged settled overnight:
- 3.6v across the LED
- 3.8A measured with the meter between the base of the cells and the tube

Partially discharged cells:
- 3.2v across the LED
- 1.8A measured with the meter between the base of the cells and the tube

As you can see, there is an issue with fully charged cells... 3.8A @ 3.6v!!!! Also, I don't think the Vf is 3.25v @ 2.8A like the binning indicates, 0.5v increase isn't going to draw an extra amp.

Can anyone else with a P7 Mag, running direct drive from Ni-MH, please measure their voltage and current?


Thanks


----------



## Drewfus2101 (Apr 24, 2008)

Wow, thats a huge swing in current with just a 0.4V drop at the emitter. I was just about to build the same setup later this week when my heatsinks arrive, but now I'm having second thoughts. I might have to go with a 4D Mag and use 2 AMC7135 1400mA boards driving it at 2.8 amps. Maybe others will chime in.


----------



## phantom23 (Apr 24, 2008)

KrisP said:


> I don't think the Vf is 3.25v @ 2.8A like the binning indicates, 0.5v increase isn't going to draw an extra amp.



Binning says 3,25V at 1,4A (350mA for each die)!


----------



## Tidra (Apr 24, 2008)

For I= 3.25 -3.5V

Yes it is just the way you measure it, so I don't know who is willing to DD P7 with 3D NiMh, because it draws too much A from the battery...

Personaly I would not recomend that.

3NiMh (NiCD) or 1 Li-Ion is the optional solution for P7 and:

1.)
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=3215

+ one

http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=1806


2.)
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=4338


in 4D there is too much voltage on the driver and too much heat is produced on the driver,...


Cheers,
Iztok


----------



## Supernam (Apr 24, 2008)

This is why I do what Drewfus does with the 2 AMC boards. I run 4C nimhs so that it holds a flat output longer, but the PVC tubes can be taken out for 3D nimhs also. Either way, the AMC boards are there to bleed off any extra power. So it's a safeguard against overpowering it. 

I'm pretty sure that in a mag host with proper heatsinking and thermal compound in the right places, that your overdriving the P7 won't be too harmful. However, keep in mind that each individual die is not equal to each other and that the one with the lowest Vf may be the first to go should you overheat.


----------



## Drewfus2101 (Apr 24, 2008)

Tidra said:


> For I= 3.25 -3.5V
> 
> Yes it is just the way you measure it, so I don't know who is willing to DD P7 with 3D NiMh, because it draws too much A from the battery...
> 
> ...



That is not an educated statement. No emitter will "draw" any more current than it is designed too at a given voltage. If it is spec'd to draw 2A at 4V, and you feed it 4V, it will draw 2A. It is that simple. You can't give it 4V and it "draw" 8A. All we can do it give it a certain voltage and the current will take care of itself. 

That is of course only talking about direct driving and does not include any drivers. 

NiMH batteries are very capable of outputting 4 amps continuous discharge without breaking a sweat. 

There are plenty of people who are DD the P7 with great results. You are better off to use a driver, but it is much more complicated at this point and there is only 1 off the shelf product designed to work with the P7.


----------



## Drewfus2101 (Apr 24, 2008)

Tidra said:


> For I= 3.25 -3.5V
> 
> Yes it is just the way you measure it, so I don't know who is willing to DD P7 with 3D NiMh, because it draws too much A from the battery...
> 
> ...



You will be fine with 4 x NiMH batteries and the AMC7135 drivers. Even hot off the charger a NiMH won't be over 1.4V, so 4 of them equals 5.6V. The AMC7135 is designed to function up to 6.0V, although heat is an issue. 

I would recommend letting the batteries settle back to 1.2V before running them just to be safe.


----------



## uk_caver (Apr 24, 2008)

<puts on sunglasses and moves to workbench>

With my experimental P7 setup (on decent heatsink, not getting very warm), running DD from 3xNiMH 17670s at various states of charge, voltage measured across LED leads.

2.96V @ 0.71A
3.06V @ 1.10A
3.15V @ 1.62A
3.27V @ 2.05A

Then, with a freshly charged pack
3.41V @ 3.41A
3.33V @ 3.00A
3.28V @ 2.75A
3.27V @ 2.66A

wait for couple of minutes to ensure LED cold (though it wasn't very warm before the wait)

3.30V @ 2.65A (taking an instant reading)
3.21V @ 2.30A (after couple of minutes running)
3.22V @ 2.20A (after a short rest)

Basically, it does seem like heat is causing a little extra current flow - after cooling, the voltage is slightly higher, but the current is lower, even though the LED isn't warming up to much beyond skin temperature.

It's also worth noting that this is a new LED, only received very recently, and until just now, barely run at high current for more than a few minutes.

After having run for some minutes at high current, even when it then cools down completely to room temperature, at 3.22V, the LED is drawing ~2.2A in instantaneous measurement compared to 3.27V @ 2.05A earlier on, so there does seem to be a 'burn-in' effect going on and dropping the Vf compared to the new LED.

However, even leaving those factors aside, it's clear the voltage/current slope is very steep.

Direct drive doesn't seem to be great for someone wanting even vaguely stable output.


----------



## Supernam (Apr 24, 2008)

It really depends on how you have the board mounted. I ran mine hot off the charger, 5.6v with 4 Accupower LSD C's. The boards are Arctic Silver'd with the chips touching the inside of the Mag tube, where I also stripped the anodizing. The boards are mounted 180 degrees from each other, not sandwiched together like the KD ones. It is also sitting on the top of the switch assembly, as far away from the emitter's sink as possible, as I found the heatsink to get way hotter than the boards. I can feel the boards get warm, but It was nowhere near hot as I left the light on for 15 minutes straight.

EDIT: UK_Caver.... Why do you suppose that you can have 2 nearly identical voltages, but with different current draw? Do you think it could be the type of battery that you are using? Perhaps they can only provide a certain amount of current depending on their discharge state.


----------



## uk_caver (Apr 24, 2008)

I think the differences between early and later results at similar currents are probably down to burn-in effects combined with heat effects, both dropping Vf, one permanently, one reversibly.

I don't see how differences of current at a given voltage can be down to any differences between batteries.

However, re-running tests with the flatter cells gives very similar results to before at low currents - it only seems to be at higher currents (~2A and above) where there seems to have been a definite small drop in Vf of a few tens of mV for a given current with a cold LED.


----------



## IMSabbel (Apr 24, 2008)

Drewfus2101 said:


> That is not an educated statement. No emitter will "draw" any more current than it is designed too at a given voltage.



One phrase: Thermal runaway.

Also, direct drive sucks.


----------



## KrisP (Apr 24, 2008)

phantom23 said:


> Binning says 3,25V at 1,4A (350mA for each die)!


Ahhh... That makes more sense 



Supernam said:


> This is why I do what Drewfus does with the 2 AMC boards. I run 4C nimhs so that it holds a flat output longer, but the PVC tubes can be taken out for 3D nimhs also. Either way, the AMC boards are there to bleed off any extra power. So it's a safeguard against overpowering it.
> 
> I'm pretty sure that in a mag host with proper heatsinking and thermal compound in the right places, that your overdriving the P7 won't be too harmful. However, keep in mind that each individual die is not equal to each other and that the one with the lowest Vf may be the first to go should you overheat.


Will 4C cells fit into a 3D? Does anything need to be modified other than needing a PVC tube?
I'm still worried that 3.8A is going to rapidly decease the LED's life 

uk_caver... Thank you for your tests. I really doesn't look like DD is a good option anymore. So much for Ni-MH having a flat discharge curve and not having high enough voltage to over drive the P7 (what has been said all over this forum).


----------



## darkzero (Apr 24, 2008)

I had one running 3 C NiMhs. 3.1-3.2A fresh off the charger then dropped to 2.8A shortly after. Never built 3D DD P7 mod though, I don't care for the D size anymore. If you don't want to run 4 cells with AMC7135s a simple resistor will take care of the issue.

Curious, at 3.6A, doesn't the color shift?


----------



## KrisP (Apr 24, 2008)

At 3.8A it was only on for 1-2 seconds to see the reading on the meter and facing at the floor but it still just seemed white. It's still under 1A per die, which P4's do without colour shift anyway.


----------



## darkzero (Apr 24, 2008)

KrisP said:


> At 3.8A it was only on for 1-2 seconds to see the reading on the meter and facing at the floor but it still just seemed white. It's still under 1A per die, which P4's do without colour shift anyway.


 
That's true. Hmm, maybe I will build me a D size & drive it at 4A to see what happens. :naughty:


----------



## Tidra (Apr 24, 2008)

Drewfus2101 said:


> That is not an educated statement.


 
Educated or not, try it yourself and you'll see how much current P7 could draw from one 18650 Li-Ion or 3D NiMH, you'll be surprised,...

I didn't say that AMC7135 couldn't take 4 NiMH, but that the heat will be produced from de driver.

Cheers,
Iztok


----------



## TexLite (Apr 24, 2008)

darkzero said:


> That's true. Hmm, maybe I will build me a D size & drive it at 4A to see what happens. :naughty:


 

With a Tri-Flupic in Burst mode,I have close to 3.6a at the emitter.I have run it like this for extended periods without worry or damage so far.No tint shift or any visible or measureable (lightbox) loss over time(~3 hours).Thats only 900ma to each die.Everything is sinked very well,including the Flupic.Output is WoW.It does get very warm,but kinda stabilizes after a while.

Michael


----------



## darkzero (Apr 24, 2008)

TexLite said:


> With a Tri-Flupic in Burst mode,I have close to 3.6a at the emitter.I have run it like this for extended periods without worry or damage so far.No tint shift or any visible or measureable (lightbox) loss over time(~3 hours).Thats only 900ma to each die.Everything is sinked very well,including the Flupic.Output is WoW.It does get very warm,but kinda stabilizes after a while.
> 
> Michael


 
Forgive me but how do you get to the burst mode? I have a Triflupic running a P7 now but in a small light. This is my first Flupic and I'm not familiar on how to fully use it yet. I only know mode 3. I highly doubt I can get 3.6a out of a R123 anyways.


----------



## Timson (Apr 24, 2008)

darkzero said:


> That's true. Hmm, maybe I will build me a D size & drive it at 4A to see what happens. :naughty:



Ahh - A true flashaholic statement :twothumbs

We're here to push the boundaries ....Who care is it doesnt last thousands of hours.... Way before the thing's given up the ghost you'll be ripping it off and installing the latest new development anyway. :laughing:


Tim.


----------



## KrisP (Apr 24, 2008)

Timson said:


> We're here to push the boundaries ....Who care is it doesnt last thousands of hours.... Way before the thing's given up the ghost you'll be ripping it off and installing the latest new development anyway. :laughing:
> 
> 
> Tim.


That's the way i'm thinking now... No point spending any more money on this as i'm sure it will last until the next generation of LEDs are released


----------



## Greg G (Apr 24, 2008)

Are the dies on the P7 the same as used in a P4? 


If they are, why could'nt we run each die in the P7 at 1 amp? Too much heat buildup I guess? :candle:


----------



## KrisP (Apr 24, 2008)

Yes, that's exactly right. It uses four P4 dies (dice?) and heat is the reason why it shouldn't be run at 4A


----------



## Supernam (Apr 24, 2008)

KrisP said:


> Will 4C cells fit into a 3D? Does anything need to be modified other than needing a PVC tube?
> I'm still worried that 3.8A is going to rapidly decease the LED's life



Other than the 1" PVC tube, you can either flip the original spring upside down, or what I did was bought a small conical spring from the hardware store for $1 and Dremel'd away the anodizing inside of the tailcap.


----------



## Gryloc (Apr 25, 2008)

KrisP,

As a response to your first post, a large increase in current draw can occur with a slight increase in voltage. Here is a table I made comparing the current draw with change in voltage (Vf-curve). I did this using a CC laboratory power supply (constant current capable). I tested the J-bin P7 here (3.25V-3.5V @ 2.8A):



(click image for larger view)
The columns on the left shows the forward voltage compared to current draw when the Pentium 4 heatsink (which the P7 is mounted to) has a 70mm cooling fan blowing a bit of air on it, while the columns on the right show it using no fan (just natural convection currents).

Just to see the logarithmic curve, here is the above data in a Vf vs. I curve:



(click image for larger view)
This graph also shows the power consumption to show how that line is not perfectly linear.

Do not forget that each die should be getting a fourth of the current (theoretically), so each die should be able to handle over 1A of current, however the thing we question with this Seoul P7 is whether the P7 emitter package can get rid of the heat produced by those dies quick enough. I tested my P7 at 5280mA since that is the maximum current that my CC power supply can handle (it is only rated to go to 5A). Each die was fine with 1320mA, but I have to have a strong fan blowing air across the heatsink so it would not over heat. Each die has a pair of bond wires each going to the anode and cathode, so they are electrically identical to a newer 4-bond wire Cree XR-E. Thermal conductivity is better per die since the dies are bonded directly to a copper slug (zinc plated?) versus the Cree XR-E, where the die is bonded to a copper pad, then a thin aluminum substrate.

If the P7 is bonded well to the heatsink in the Maglite, and the flashlight body is dissipating the heat okay, then I see no problem with running your P7 at 3.8A. In my P7 Maglite (2D with 2 parallel D-sized li-ion cells), I plan for a max current of 4A. I will have George80's D2DIM circuit to allow me to dim the P7 (via PWM) for the bulk of the flashlight use, with the 4A turbo mode (100% duty) for blasting through a field, or for show (with no more than 15 min of consecutive use). Of course this is with DD'ing the P7 with li-ions, which will have a slightly lower maximum voltage at full charge than the 3x NiMH cells.

For best results, I would stay below 3A (longer battery life, less heat). I usually like playing on the dangerous side by "overdriving" LEDs at higher currents than most would. I suppose that if you would shorten the life to a few thousand hours, you would never really notice a drop in output during use after years of use (unless you use your light all night while on duty or something), so why not get some "fun" out of it? For many modders (me included), they will switch out the emitter when a newer and better one comes out before the original goes bad. If you would damage it (leave it on over night next to a heater in the winter or something), then they are not too difficult and expensive to replace. However, if this is for a gift, then keep the currents low to err on the safest side. I guess that I mean that you should not run the P7 at currents that you are not comfortable with. The P7 will not die the instant that you send over 2.8A of current to it, so no immediate alarm. Thermal runaway with DD is a problem unless you know that it will not get out of hand with your choice of batteries or electronics.

I would like to hear evan9162 chime in about heat. I need to get a hold of him to see if I can get him a new Seoul P7 to test fully. Good luck and happy modding!

-Tony


----------



## TexLite (Apr 25, 2008)

darkzero said:


> Forgive me but how do you get to the burst mode? I have a Triflupic running a P7 now but in a small light. This is my first Flupic and I'm not familiar on how to fully use it yet. I only know mode 3. I highly doubt I can get 3.6a out of a R123 anyways.


 
darkzero,I posted in your other thread.Your mod caught my attention before I checked this thread.Level 1 and 2 are the ones programmable for output.Level 3 is Burst which is set at up to 1200ma,or whatever the batt/s are capable of,which may be less.

Here is the flowchart if you dont have it already,https://www.candlepowerforums.com/threads/123520



Gryloc said:


> If the P7 is bonded well to the heatsink in the Maglite, and the flashlight body is dissipating the heat okay, then I see no problem with running your P7 at 3.8A. In my P7 Maglite (2D with 2 parallel D-sized li-ion cells), I plan for a max current of 4A. I will have George80's D2DIM circuit to allow me to dim the P7 (via PWM) for the bulk of the flashlight use, with the 4A turbo mode (100% duty) for blasting through a field, or for show (with no more than 15 min of consecutive use).


 
Gryloc,great chart and information about the P7.
In my current setup I have the emitter bonded to the anodized heatsink with thermal epoxy,the driver is bonded chip side(all connections made on the backside) to an H22A heatsink with the lip removed,in between the switch and the emitter sink.Everything is assembled with a ton of thermal paste,including on the threads between the body and head.The body gets warm to about midway of the switch,the head gets as warm as the body in front of the switch.Head finning would be very beneficial in my opinion.It pretty much stabilizes after short while,but it does get warm pretty fast.I run it mostly around 2a.



Gryloc said:


> For best results, I would stay below 3A (longer battery life, less heat). I usually like playing on the dangerous side by "overdriving" LEDs at higher currents than most would. I suppose that if you would shorten the life to a few thousand hours, you would never really notice a drop in output during use after years of use (unless you use your light all night while on duty or something), so why not get some "fun" out of it? For many modders (me included), they will switch out the emitter when a newer and better one comes out before the original goes bad. If you would damage it (leave it on over night next to a heater in the winter or something), then they are not too difficult and expensive to replace. However, if this is for a gift, then keep the currents low to err on the safest side. I guess that I mean that you should not run the P7 at currents that you are not comfortable with. The P7 will not die the instant that you send over 2.8A of current to it, so no immediate alarm. Thermal runaway with DD is a problem unless you know that it will not get out of hand with your choice of batteries or electronics.


 
I totally agree,I plan on building some to give to family that will use the drivers with 7135 chips.Output will be limited then to around 2400ma.But in my current set-up the Flupic goes from ~2200ma to ~3600ma,with nothing in between.I would prefer to run it in between those currents,but nothings available yet.

Thanks for the good info.

Michael


----------



## KrisP (Apr 25, 2008)

Thanks for all the replies... I couldn't resist and ordered a tri-flupic for it 

Texlite... I have a tri-flupic in another light and I was sure level 10 and max brigthness were the same. I set interface 1 to give 1, 10, MAX and I couldn't see any difference between 10 and MAX... Maybe my battery couldn't supply the current for MAX or something.


----------



## TexLite (Apr 25, 2008)

KrisP said:


> Thanks for all the replies... I couldn't resist and ordered a tri-flupic for it
> 
> Texlite... I have a tri-flupic in another light and I was sure level 10 and max brigthness were the same. I set interface 1 to give 1, 10, MAX and I couldn't see any difference between 10 and MAX... Maybe my battery couldn't supply the current for MAX or something.


 

For my sake I hope it was your battery,otherwise I've lost one channel,until it goes into DD/burst.I wont know for sure until I get another put together,or I pull my current setup apart and check.I was wondering that but hadn't asked anyone yet.Thanks for the info.

Michael


----------



## Christexan (Apr 27, 2008)

Saying an LED "if designed to run at 1A at 4V, give it 4V and it will take care of itself" is completely incorrect and false. If an LED is designed to run at 1A at 4V at Tj of 25C, THEN it is reasonably correct (ignoring production variation).... the problem is the moment you turn it on it starts heating up, and every C increase drops the Vf required to maintain a given current.... so you turn it on, and feed a constant 4V... it heats up 1C, and now it only needs 3.9V to run at 1A.... so now it's running 1.1A... and heats up another C, Vf drops, current rises... heats up more... that is the FUNDAMENTAL rule of LEDs and thermal runaway, running a constant voltage with disregard to current limits and temperature at the junction, and running at the "spec sheet" limit (ignoring the specs CLEARLY state something like "at Tj=25C") is to ignore at your peril. That's what the temperature derating charts on the spec sheet for, so that you can adjust accordingly (and/or run a constant-current driver and not have to worry about it).


----------



## StefanFS (Apr 28, 2008)

TexLite said:


> I totally agree,I plan on building some to give to family that will use the drivers with 7135 chips.Output will be limited then to around 2400ma.But in my current set-up the Flupic goes from ~2200ma to ~3600ma,with nothing in between.I would prefer to run it in between those currents,but nothings available yet.


 
If you were to build an AMC7135 based SSC P7 driver from one 1A multimode driver with a slave sandwich consisting of two simple 1A AMC 7135 boards you get 3A. If you use one 1A multimode with one 1.4A + one 0.35A you get 2.75A.

These AMC7135 based drivers have similar behaviour compared to the FluPIC design, similar discharge curve etc.

I built a 3A driver that works well:
https://www.candlepowerforums.com/threads/195358

Stefan


----------



## KrisP (Apr 28, 2008)

I don't like the AMC7135 boards. I only use them for home lighting with 5vDC power packs because in that situation I don't mind them wasting power.


----------



## StefanFS (Apr 28, 2008)

KrisP said:


> I don't like the AMC7135 boards. I only use them for home lighting with 5vDC power packs because in that situation I don't mind them wasting power.


 
Yes, a lot of people don't like them. That's fine. My point was that it's possible to combine drivers to get different currents, eg. 2.4A, 2.7A or 3A to the emitter. Others find them very useful. They provide a very cost effective solution for driving the SSC P7 at different currents. They don't waste power when used properly within the preferred voltage range with suitable cells. The multimode AMC7135 drivers share some basic concepts with the FluPIC design and to the end user the result is similar(like the discharge curve). Of course, the programming and timing is different. For example, all my FluPICs have a difficult time with forward switches due to the timing.
Stefan


----------



## KrisP (Apr 28, 2008)

Sorry, I didn't mean to sound rude in any way


----------



## StefanFS (Apr 28, 2008)

I didn't think you were. I just wanted to be clear about my thinking/reasoning about those drivers. It's your thread I'm invading!
Stefan


----------



## Greg G (Apr 29, 2008)

KrisP said:


> Hi,
> 
> 
> Can anyone else with a P7 Mag, running direct drive from Ni-MH, please measure their voltage and current?
> ...


 
I built a [email protected] 3D P7 DD off 3 "D" size Accupower LSD batterries tonight. FiveMega MOP reflector. Fresh batterries off my Maha 808M give me 3.6 volts at the emitter, and 3.61 amps at the tailcap. 

It's bright with a huge hotspot. I took it outside and compared it to two other [email protected] I've built. The P7 is a little better than my tri Cree 3D [email protected] (R2's @ 1 amp via a Shark, McR19XR reflectors, and 3 D Accupower LSD's). 

It won't get on my penta Cree :naughty:, but I didn't expect it to. 

I ran this light for about 15 minutes straight and the head got warm, but not bad at all. I don't think I'll bother with finning the head unless it's for looks. 

This is probably about as much light as I can get out of 3 NiMH's. Definitely cheaper than a tri- Cree as well. 

The beam isn't perfect, it still has a small artifact right in the center, but it's hardly noticable. 

When the Sandwich Shoppe comes out with a dedicated driver for this pill I'll put one in for flat regulation. But I want to stay around 3.5 amps current.


----------



## KrisP (May 3, 2008)

With the tri-flupic fitted now, the current draw at the cells is 3.1A on MAX with freshly charged cells.


----------



## cytoe (Aug 25, 2008)

*would this work?*

To get full power and a "dim" mode, could I use http://www.dealextreme.com/details.dx/sku.1886 (2 pieces) run in parallel? so w/ one operating, it would be 1400ma. To get full power (2800ma), connect the 2nd one in parallel. Would this work?


----------



## uk_caver (Aug 25, 2008)

Assuming the switching is arranged appropriately, that should work fine - the 1400mA driver uses 4x 7135 run in parallel, and there's no reason that multiple boards can't also be paralleled.


----------



## cytoe (Aug 26, 2008)

if I put the switch on the battery side of the 2nd driver and it is off, would there be a problem w/ the led +/- leads getting current from the other driver's led +/-? Or would it be better to switch both the input and output off/on at the same time?
thanks for the help!


----------

