Modding a Planet Bike Super Spot?

So while I have been figuring out what I am going to order to make my achesalot style light, I decided to pick up a Super Spot to keep me a bit safer while just on the road these days. However, now I have been bitten by the mod bug...

Upon taking a quick look at the light here are some thoughts and questions:
-It runs on 4 1.5V AAs, looks to be in series, so would that be equivalent to a single 6V battery?
-Just going on looks, I think a Seoul P4 (bare emitter) would be the easiest to fit.
-The fit will be tight though, there is a recessed spot in which the current emitter fits right into on the heatsink. (I guess I could file it down though.)
-It is supposedly a 1W light.. and from what I have heard it uses "Gen. III 1W Luxeon Star" emitter. (Does the P4 have comparable dimensions?)
-What resistor would I want to look at in order to drive a P4 at a decent current? (By the looks of it, I should be able to cut out the old resistor and solder in a new one.)

Any tips/help would be great!
(If pictures would help, I might be able to put some up later.)

-Just going on looks, I think a Seoul P4 (bare emitter) would be the easiest to fit.
--Recall the heat sink of a Seoul is conducting and may need to be electrically insulated with something like Artic Silver Epoxy.

-The fit will be tight though, there is a recessed spot in which the current emitter fits right into on the heatsink. (I guess I could file it down though.)
-It is supposedly a 1W light.. and from what I have heard it uses "Gen. III 1W Luxeon Star" emitter. (Does the P4 have comparable dimensions?)

--Dealextreme has a link to the Seoul LED. I read 8mm diameter for the physical LED body on the spec sheet, but do not claim to be a Seoul expert. The LED leads extend farther (14.50mm).

-What resistor would I want to look at in order to drive a P4 at a decent current? (By the looks of it, I should be able to cut out the old resistor and solder in a new one.)
---Most people would use a switching regulator as resistors are inefficient for battery life. Sources could be Sandwicheshoppe or DealExtreme. More current= more lux, but less efficiency (typically dropping from around 350ma).

Beam pattern is also important for bike LED lights as they are not the same.

Nate

NateTheGreat said:

-Just going on looks, I think a Seoul P4 (bare emitter) would be the easiest to fit.
--Recall the heat sink of a Seoul is conducting and may need to be electrically insulated with something like Artic Silver Epoxy.

-The fit will be tight though, there is a recessed spot in which the current emitter fits right into on the heatsink. (I guess I could file it down though.)
-It is supposedly a 1W light.. and from what I have heard it uses "Gen. III 1W Luxeon Star" emitter. (Does the P4 have comparable dimensions?)

--Dealextreme has a link to the Seoul LED. I read 8mm diameter for the physical LED body on the spec sheet, but do not claim to be a Seoul expert. The LED leads extend farther (14.50mm).

-What resistor would I want to look at in order to drive a P4 at a decent current? (By the looks of it, I should be able to cut out the old resistor and solder in a new one.)
---Most people would use a switching regulator as resistors are inefficient for battery life. Sources could be Sandwicheshoppe or DealExtreme. More current= more lux, but less efficiency (typically dropping from around 350ma).

Beam pattern is also important for bike LED lights as they are not the same.

Nate

Click to expand...

Thanks for the response!

-When you say the heatsink of the Seoul is conducting, what do you mean? I guess I assumed that with a bare emitter the only bits that would conduct are the leads.

-Hmm, I guess I will find spec sheets for both and see if I can't find my fit/sizing answer from those.

-My reason for using a resistor would be that it already uses one, and so this would be the easiest way to mod it, by far. Just how much less efficient is it? If I wanted to use a switching regulator thingy then the cost would go up, the modding/re-wiring would be much more involved, and it might not even fit in the housing (how small are these things?). I probably wouldn't bother unless the improvement in efficiency would be quite big.

-Ah yes, beam pattern... well, to be honest, the beam pattern of this light sucks to begin with, so it couldn't get too much worse... and as it will primarily be either a "be seen" light or strictly a backup when on trails, I am not worrying too much about the pattern, more about the output. That being said, the current reflector is 14mm tall (not including legs) and 40mm wide... any ideas what I could replace it with? (Something narrower could work too.)

Thanks again, the help is appreciated.

I too am interested - I posted this same headline almost a month ago and no bites, glad you got some. I'm looking at dropping in a more effecient 1W so I don't have to start hacking the case to make room for a heat sink. As well, I too would rather work with existing resistor to keep the case chiseling to a minimum.

As for the beam pattern - it's much more of a flood pattern which I find very useful, especially on trails (But it does not fit the name Plaent Bike decided to give it). If you had a similarly powered spot it'd be a decent set up, one flood and one spot.

jdkimple said:

I too am interested - I posted this same headline almost a month ago and no bites, glad you got some. I'm looking at dropping in a more effecient 1W so I don't have to start hacking the case to make room for a heat sink. As well, I too would rather work with existing resistor to keep the case chiseling to a minimum.

As for the beam pattern - it's much more of a flood pattern which I find very useful, especially on trails (But it does not fit the name Plaent Bike decided to give it). If you had a similarly powered spot it'd be a decent set up, one flood and one spot.

Click to expand...

Well, I think I might just drop in a P4, see how that works, and then decide whether or not to mess with a different resistor or a regulator of some sort.
In regards to the beam pattern, I really don't like how it has those vertical stripes... taking off the "lens" removes those stripes and allows for a lot more light to be shown. I am hoping I can find something very clear to fit in there, or that I can shape to fit in in place of the current cover/lens. The downside is that without the stock lens thingy there is a "donut" shaped hot spot. I might actually try to find a different reflector depending on how the p4 works, or I could shim this one out to make the "donut" come together to form a tight hot spot. I think I will also pick up a newer mount that should be able to fit my oversized bars.

Just because of how cheap it is, I might also pick up a 1-watt Shark LED light from MEC... and of course look at how I can mod that too! :thumbsup:

Quick follow-up... I just remembered about the LED Pro program and it gave me a resistor of 3.33 ohms to get 750mA current. So assuming that isn't horribly inaccurate, I think I will use that to figure out what resistor to use.

One question though... what kind of (AA) batteries should I use to get a decent battery life out of this modded light? Any tips would be great!

What batteries indeed... tho I am looking at some 2500 maH ones in NiMH.

And the "stripes" - yeah, I know what you mean. Not my favorite, but better than none I suppose. Maybe this could be aided by some optics? Perhaps like what's on my Task Force 2C flashlight. THAT would be some tight hotspot.

And let me know what you think of that MEC Shark - I was looking at that too until I got the Task Force. But if it's bright enough, with a better run time, that would be if interest.

This is an old thread, but I'll add this in here for posterity...

I just dropped an SSC P4 into my Super Spot last night. It's a definite improvement.

The stock 1w Luxeon is soldered to a round disk that is screwed down onto a heat sink with 2 small machine screws. This disk contains the electrical connections (solder pads) for the Luxeon. The center of the disk is hollowed-out, it's really a donut -- the heat sink protrudes up through the center of the donut terminating in a sort-of cradle for the LED, which sits on this protrusion with some thermal paste underneath.

I had originally thought that the Luxeon was simply mounted on a round MCPCB, and was looking to buy an SSC on a similar round board (vs. a star), but once I looked more closely at the light I figured out that it's some sort of custom mount. I suppose you could grind down the central protrusion on the heat sink and then mount a round or star MCPCB emitter on it.

I don't think you need to worry about electrical isolation for the replacement LED because the heat sink isn't really grounded. Two wires run from the donut disk through the heat sink and on to a tiny PCB containing the switch and 5.6 ohm resistor. One wire is black and the other is red. If you remove the screws and raise the donut disc, you'll see a plastic insulator around the red wire to insulate it from the heat sink.

Simply open up the light, unsolder the Luxeon from the donut, and then replace it with the SSC P4. Really straightforward -- just remember to check the polarity on the new LED and add some more thermal paste.

Also, FWIW there seem to be different versions of the Super Spot lens/optics. I have two: one which has a squarish central spot to the beam and the "stripes" in the outer areas of the beam; the other has an oval central spot and less striping in the beam. The light that I modded is the second one with the oval beam, which PB sold me for $10 as a "refurbished" model.

Next step is to improve the heat sinking and replace the simple resistor with a regulated-current driver, trying to bump the output up to around 750mA.

Hi. I'd like to share my success also with Seoul-ify my Super Spot. My version is the squarish beam. Unlike yours, the heatsink on mine is electrically negative, so to prevent an electrical short you either have to isolate the Seoul's positive-tied heat slug with some mica or kapton, or re-wire the Super Spot so the heatsink is positive. I chose to do the latter since isolators would reduce the heatsink's effectiveness. Plus, the Seoul is naturally higher than the Luxeon, so it messes up with the focus a little. An isolator would make the situation worse, but you can rotate the heatsink to back out the LED to compensate. Once you take care of that, the bare (unmounted) Seoul LED just drops right in place of the Luxeon, but in "reversed" polarity. A fresh application of thermal compound is a good idea at this point. There seemed to be very little of it applied at the factory.

The SSC P4 Seoul swap alone will double the light output, but keep power consumption the same at 1W. That's not good enough for me , so I chose to crank up the power to 2.6 watts by bypassing the 5.6 ohm resistor and installing a small buck regulator from dealextreme modified to output 800mA. The stock heatsink is inadequate to handle this much power, so I "enlarged" it by epoxying in several pieces of 12 gauge copper wire, which were bent back to fit right behind the reflector. Thermally conductive epoxy, like Arctic Silver, is a must here, since regular epoxy is a heat insulator. Without the heatsink mod, I measured the heatsink at 195F and the beam color turns very bluish, so the LED was overheating. With the mod, the heatsink temp get to 145F, a 50F improvement, and the color/tint seems to be stable. Here's a picture of the modified heatsink attached to the reflector:
http://www.geocities.com/desolder/planet_bike.jpg

The end result is the same funky beam pattern, but it's now about four times brighter. Theoretical runtime is cut in half, to a little over 4 hours with 2500mAh AA NiMH's, with current draw measured at the batteries at ~600mAh. I have two of these mounted on my bike and I have no problems trail riding at night at a moderate (10-15mph) speed.

DanU said:

The SSC P4 Seoul swap alone will double the light output, but keep power consumption the same at 1W. That's not good enough for me , so I chose to crank up the power to 2.6 watts by bypassing the 5.6 ohm resistor and installing a small buck regulator from dealextreme modified to output 800mA.

Click to expand...

What DX buck regulator did you use? Thanks!

Hi sfCyclotourist,
I used the SKU 3256 driver. It's rated for 3.6 to 9V input, 800mA output, but the ones I received measured an output of 900 to 1000mA. As suggested by James_C in the discussion section, you can reduce this to your liking by filing/shaving down the current sense resistor R2.

The converter efficiency is quite good in this setup. I calculated 90%. Not bad for a circuit that costs a mere $7 for four units.

While I was was waiting for the shipment, I also tried a simple resistor swap using a 2 ohm resistor. Measured current was about 700mA, LED wattage was 2.2W. The efficiency is only 65%, but at least it gives you a huge light boost while you're waiting for DX's free but slow shipping.

One thing I forgot to mention is that I had to nibble about 1/8 inch from the "front" edge of the circuit board holding the clicky switch to make way for some of the copper wires glued into the heatsink.

Hi DanU, Can you post a picture somewhere else - the one you linked is not gone? Did you have to modify the heatsink to fit the Seol LED (it has a raised platform right under the LED)?