Driver for SSC P7 LEDs

[agust]

I just got the light in today. It does appear under driven so I'll be ordering a new one of those.
It doesn't have a very tight hotspot either. Can anyone help explain how to fix this?

Hi adm3745, can you post the result after the driver switch? Also I'm curious about how much current the default driver is delivering at max. Thx alot.

 

[meesier42]

I have 2 of the DX lights coming in, has anyone verified that the Driver that Packhorse identified will fit in the lighthead. I have no issues swapping the driver so long as it fits. of course there is the second question about the operation of the switch using the installed reed switches with the new driver, if they are integrated into the original driver board this would also be problematic.

 

[martzak]

I just got the light in today. It does appear under driven so I'll be ordering a new one of those.
It doesn't have a very tight hotspot either. Can anyone help explain how to fix this?

From my experience most LED flash lights will not have a tight spot. LED lights are more flood than throw. The only way to tighten the spot is to use a different reflector. Please somebody correct me if I'm wrong.
The flashlight in my home-made dive light is a spiderfire from DX. It does have a hot spot, but it's sorounded by a flood of light. I've used both types of lights underwater, thrower and a flooder. I personally like the flooder better as I can illuminate a large area around me as opposed to a 12inch circle 100ft away from me.

 

[martzak]

Although a high-current, efficient driver is the best way to get the most out of an LED light, all drivers I've seen out there fall short, either because they're over-spec'ed or not efficient. The few home-made driver circuits out there that appear to work as advertise, cost >$35 shipped. The easy and cheap way to get around this is to put 6 18650 batteries in parallel; $20http://www.dealextreme.com/details.dx/sku.19770

In about 2hrs of continuous burn time the current drops from ~2.8A to 2.0A, which is still better than using the driver from DX which outputs 1.8A max.

 

[martzak]

Just keep in mind that the LED can/will die in two ways:
- exesive heat, even when working within the current rating of the LED (which will of course be less of a problem working under water)

- too high a current through the very thin internal gold wires - this is the one I am warning folks about.

If you over-drive the LED even for a short period (easy to do then the batteries are fresh and you are in a direct drive mode with no driver/regulator to control the current), you run the risk of exceeding the max. current through the LED, which will permanently damage or destroy the LED. In these P7/MC-E's with multiple individual dies in a single package, damage could be as little as loosing one or two, up to loosing the whole array of LED's, which means having to replace the assembly. At the CandlePowerForums some folks have over-driven the LED and it appeared to work well for a little while, and then the LED died completely, so the failure from an over-driven situation could be quick/instant, or take a little bit to take effect.

Just my 2 cents.

Will

Read this before attempting direct driving your LED.

 

[martzak]

Update to the SSC P7 driver saga. Got this driver from http://www.kaidomain.com/ProductDetails.aspx?ProductId=6386

On the input side I had 2x18650 cells in series, 7.81V open circuit voltage.
On the output side SSC P7.
Results:
time Output current (current through the LED)
0 3.16A
3min

 

[martzak]

oops.
here are the results:

time Amps to LED
0 3.16
3min 3.13
6min 3.15
8min 3.13
10min 3.16
15min 3.15

The mosfet got hot to the touch but no smoke. 3.1A output current is a little higher than I would like to run through my LED but it's better than any other off the shelf driver I've tried out there. The light is noticeably brighter than with the SSC P7 driver off deal extreme, at the risk of damaging your LED without proper cooling.
I checked the n-MOSFET on this circuit, it is rated for 60W.
I'm going to use this on my SSC P7 dive light and post results, aka let know when my LED craps out.

 

[Packhorse]

Many people have problems with that driver.
I have used it many times and always heat sink it and never have issues though.

 

[martzak]

What/how do you attach the heat sink to?...could you please post a picture or two.
I was thinking about attaching a heat sink to the MOSFET since that's the component that heats up the most.
Thanks.

 

[350xfire]

What/how do you attach the heat sink to?...could you please post a picture or two.
I was thinking about attaching a heat sink to the MOSFET since that's the component that heats up the most.
Thanks.

I take a piece of aluminum and machine a hole in it and recess the driver in there. I use some of the thermal glue to keep it in place.