ssc p7 c bin question

[showlyshah]

hey dudes is it safe to drirect drive a c-bin p7 with 2 paralleled protected 18650 which gives a total op of 3.7 at 4000 ma? Though the voltage wil be below 3.5 v after all resistance offered by wires,spring, and switch.

Also is it possible to solder the p7 diode to a coper heat sink? Like the xp-E is mounted on star pcb. Coz i dont want to use artic alumina epoxy to paste the diode to the heatsink.

 

[LEDninja]

The 18650 batteries charge up to 4.2V. I measured 2.7-2.8A in my Elektrolumens EDC-P7 with 1 18650.
2*18650 in parallel just doubles runtime.

I believe the case bottom of the SSC-P7 is electrically active. So you will have to isolate them from the heatsink. Use thermal epoxy between the LED and heatsink.

 

[showlyshah]

ok dude. but i measure only 3.5v from my battery. and its written 2000ma on the battery. actually its a code less phone battery. but i am sure that it is a 18650. though the amp is only 2000 ma.

so u r saying that it is safe to drive the led? then how do u over drive the led? is it just increasing the led vf? and not the current?


dude i am planing to make the body of my torch as the negative contact. and since its a direct drive, is it possible to keep the led soldered and the positive terminal will be isolated?

 

[jhMadCow]

Li-ion batteries have a resting voltage of 3.7v, a fresh off the charger Li-ion will read 4.2v sometimes. Your battery has 3.5V, that just means that it needs charging.

The P7 is rated for 3.6-3.7v, I'm wanting to bet that a 4.2v battery is going to kill a P7 direct drive. Why don't you want to get a simple driver that will keep the voltage stable? Single mode drivers can be had for $5 on Kaidomain.

 

[LEDninja]

Both my Elektrolumens EDC-P7 18650, and my Mag P7 3C are direct drive. I have no problems so far (~18 months). Longest run was ~1 hour during a hike in Toronto's High Park.
The Cree MCE has a lower Vf & a smaller base and there were some reports of burnt out LEDs.

 

[showlyshah]

Dude i said that the batt is 3.5 v becoz the protection board inside the battery pack is designed to give a max o/p of 3.5 v @ 2 amp when its fully charged. And it also have a under/over discharge/recharge protection too. We can directly connect a 6v tranformer based charger to the cell. And it wont damage the cell.
So my point is that it will never give more than 3.5 v.
I have used the same cell for my 5w led tourch along with a transformer based charger and it serves me good.
So the only problem with me is that in terms of the amp. Does the led will take only 2.8 amp from a parallel setup of 2*18650 which has a potential of giving out 4 amps? Or it will fry out?

 

[LEDninja]

At 3.5V the LEd should stay at or below 2.8A. Should not fry.

 

[showlyshah]

Ok dude. I have few more doubts.

Can i solder the p7 base to a copper heat sink?such as cree's are fixed on mcpcb's?

If the led take only the amp it needed from a supply capable for providing much more amp's, then how can we overdrive the led? Is it the Vf do the trick? Or is it the If? Pls help me

 

[Al Combs]

Like LEDninja said in post #2, the slug of the P7 is common to the anode or positive terminal of the LED. You might develop a short unless you took steps to isolate it from the ground. One possibility there would be to just put the batteries in backwards. Of course that depends on what flashlight you use.

SSC recommends end users attach the LED to stars or whatever with thermal epoxy. It's the pdf towards the bottom called "Spec". That's really more of a disclaimer of liability on their part if you damage the LED. That aside, many people have reflowed LED's using common houshold items. I did that in a recent build with a stick lighter I use to light the grill. An idea I got from member LED Zeppelin. I've seen a couple of posts where people put stars on the element of an electric stove. Heat guns work if you happen to own or have access to one. Ordinary 63/37 solder only needs 183°C to melt.

The P7 spec. pdf can help answer your other question about forward voltage. There is a logarithmic graph at the top of page 6 called, "Forward Voltage vs. Forward Current". At any given voltage, the LED draws a certain amount of current. So there are many different forward voltages. The one of interest is how much voltage it takes for a P7 to draw 2.8 amps. It is different for every LED. The only way to know what the Vf of a particular LED is, is to measure it. Also the Vf drops as the LED gets hot. Current is the slave of voltage with LED's. Even though current is what you are trying to control.

The C bin you mentioned refers to the P7's output. Under the newer ratings a C bin put out 700 ~ 800 lumens at 2.8 amps. The last letter of the 5 letter Code labeling is the forward voltage. They explain on page 2 of the spec sheet what the different letters mean. But you have to download the "P7 series binning & labeling" pdf to get the chart that has the numbers of interest. As a for instance I bought a DSVNI from PhotonFanatic. The "D" means 800 ~ 900 lumens. While the "I" means 3.25 ~ 3.50 volts. "J" bins need 3.50 ~ 3.75 volts so those are what people usually want for direct drive. The middle three letters are the color bin. Look at the one labeled "SSC Z-Power (All) (Pure White)". I had a pair of DX paralleled regulators to give me 2.8 amps. The voltage I measured at the LED was 3.28 volts while drawing 2.84 amps. I don't think it would have lasted very long being direct driven from a Li-Ion.

I almost forgot... :welcome:

 

[showlyshah]

but my problem is i bought the led from a retailer. And it comes in a small box, inside which the led is kept in an aeroform. So the only detail i know is that its a c bin. As the seller told me that it have 800-900 lumens at 2.8 amp. So is there any way to physicaly identify the led? I meen by looking into die? Can i identify the bin?

 

[LEDninja]

Your seller is using info he made up himself. Not actual SSC spec.

The old SSC spec for C bin is 740-900 lumens at 2.8A. This is an estimate and SSC just threw the high 900 in there so they do not have to rewrite the spec when they make better LEDs. Very few if any LEDs make it to 900.
The new spec for C bin is 700-800 lumens at 2.8A. This is what SSC can actually produce.
the new spec for D bin is 800-900 lumens at 2.8A. The few LEDs that actually test higher than 800. There is no guarantee any of the LEDs actually make it to 900.

I suspect your seller saw 800-900 listed at CPFMP where they are selling D bin and just copied the numbers, not realizing he is selling a different bin.

Most current SSC-P7 are binned as follows:
C(orD) XO(orWO or other tint) I(orJ).
C or D brightness at 2.8A.
XO or WO or other tint.
I or J is Vf. I 3.25-3.5V, J 3.5-3.75V

So you have a LED somewhere between 700 and 800 lumens at 2.8A and a Vf somewhere between 3.25 and 3.75V.
As you are not using a regulated driver, you are probably putting somewhere between 2.5A to 3A at the LED. So it is not worthwhile getting picky about the other numbers.
Still remember you are ~4X the brightness of the SSC-P4/XR-E/XP-E LEDs and double that of the XP-G.

-

All the LEDS are made on the same assembly line then tested and binned from the testing. So the LEDs look identical and you can not tell the bin by looking at them.

 

[showlyshah]

So now i am going 4 the work.
I have one more question.
What should be the min diametre and depth of a reflector that i have to use in order to get a throw of about 400+ meters using p7. Can i achive it using a modified stock mag 2d reflector?

 

[LEDninja]

The P7 is a FLOODY LED. You will not get 400 meters throw unless you use a reflector a meter wide or an aspheric lens.

Here is selfbuilt's review of his more powerful lights:
http://candlepowerforums.com/vb/showthread.php?t=255044
The only light that can go 400+ M is an HID.
The SST-90 (about 3.5X the output of the P7) is above 300 M.
The SSC-P7/MCE/SST-50 lights are in the 150 M range.

You can use a Mag reflector with the P7. Just have to cut the cam off so it does not bump into the heatsink.

 

[John_Galt]

There's no way you're going to get 400meters of throw from the P7/MC-E LED's. You would have trouble getting that with an overdriven SST90 LED, and a large reflector.