Stanley FatMax Tear-down, mods & 5000K beamshots

I was finally able to get my Stanley fatmax apart today. They key was a new 3mm allen wrench. I guess mine was more worn out than I thought…
Remove the front rubber bezel piece, 4 allen screws and heatsinks. Use a sharp knife and cut the foam gasket tape underneath the rubber bezel, at 2 locations where the halves come together.

Remove the kickstand by prying off the 2x black covers and 2x screws. The part is flexible plastic so just carefully stretch and pull it off.

Remove black screws around the perimeter

Pry the handle grip HERE: Its rubber skin glued onto plastic, so make sure your knife edge gets underneath the plastic frame layer.

Remove one more screw in the handle

You should be able to lift the halves apart.
Circuit board. Just as I feared everything is Integral on one board. Charging circuit, HI-LO program modes and EPROM controller + LED driver. Modding this is going to be an “all or nothing” affair. Thats kind of a bummer.

Cast aluminum heatink

LED star, held down with screws and thermal grease

Plastic reflector (mine was very dirty and dusty, this was pretty much my main reason for wanting to take it apart, that and of course scoping it out for mods). I was also able to center the LED better…. no more egg shaped hot spot.

This stupid thing however was my biggest peeve about the light. They use a rubber gasket around the lens, and its really too small and thin of a material. So it “falls off” the glass, and into the path of the light under its own tension. Imagine trying to stretch a ~1/4 thick rubber band around the edge of a dinner plate. My solution was to cut it and alleviate the tension so it would stay snugly in-place around the perimeter of the glass without sliding off and into the reflector area. Thank goodness thats fixed!! They got it right though with a well made glass window. Its not AR coated, but its better than the cheap plastic I have seen on other LED spot lights.

2x18650 in series. The additional wires are for the balance charging circuit built into the OEM board.

2000mah spec’d, made in China

Higher res images of the board (56K!!!)
Can anyone ID the current sense resistor?

I re-attached the heatsinks and ran the light on the bench for 15 mintes. It did get very warm, but not what I would consider alarmingly hot, or skin-scalding hot. So it most definitely is under-driven to some degree. Neat thing about this design is I could touch the flat area RIGH beneath the heatsink and really monitor thermals from the source of the heat, all the way through the conduction path. I believe its most definitely a cast aluminum chassis assembly. The temperatues rose slowly and uniformly through all the heatsinking materials. At no point could I feel a drastic difference in temperature resulting from the thermal junction between the cast metal and the black anodize metal. IMHO Stanley engineers did their homework on this one.

It probably wouldn’t be too hard to mount a TIR optic in there and get a more open flood-beam.

Current draw from the 2x cells: Really easy current load on the cheap 18650 cells. I forgot to take a measurement on LO though… Oops.

Flipped the meter to read AC-Hz and I could not measure any PWM.

I think theres some real mod-potential here. The OEM switch is spec’d at 25V / 5A. So while it certainly can handle the load of a 3-3.5A draw there could be some resistive/parasidic activities going on there.

Cool. Thanks for taking it apart. Everytime I try something like that, I bust it all to hell.

nice work, thanks for posting that.

so glad to see they used a pcb for the emitter. the 5W and waterproof xr-e lights do not, which makes them tough to mod.

Just placed an order for 2x CGR18540EA

And I’m picking up one of Craigs 3A-7135 drivers, a 5000K XML on a star and some AS-5 tomorrow.

Hopefully in a week I’ll have this one up and running.

Hi Kramer5150,

Can you please take a measurement of the reflector diameter and depth, Is there any space to get one or two additional 18650’s or a lipo pack of some sort?


Edit, I am wondering if changing the value of any of those resistors might get the current delivered to the led up.

Right. That would not have gone well for me either.

On the second pic, lower right corner by the edge, it looks like there are three low value resistors in parallel. (1, 050, and 050)… those look like they are the current sense resistors. If I’m reading them right, the combined value would be 0.2 ohms.

So is it just a matter of taking them off one at a time and seeing which configuration is brightest?, trial and error kind of thing?

Taking one off would make the light dimmer. To increase the current, you would need to add more resistance in parallel, which would lower the total sense resistor value.

Paralleling in a 1 ohm resistor would increase the LED current by 20. Adding a 0.5 ohm resistor would increase the current 40… assuming that the circuit works as expected and the original sense resistors added up to 0.2 ohms. If not, Magic Blue Smoke could escape.

Can’t seem to figure it out; which resistors are you referring to?

I should have said “lower RIGHT corner” in the second high-res pic…

I think they are the ones on the bottom right in the pic below… R050, R050 and “T” (looks like 1).
FWIW the red and black wires at the bottom right corner power the XML.

Are there any other opinions on this?

OK thanks
Based on ceiling bounce comparisons to my other XML lights, I think the Stranley is in the ~700 Lumen vicinity. After observing its thermal characteristics, I speculate its pushing the XML with 2 - 2.3A.

A 40% increase from there would land it at 2.8 - 3.22 Amps

Does anyone else have opinions on this kind of mod?

Boldly go… it’s only 50 bucks and some magic blue smoke if things go wrong… or horrible, painful death and dismemberment if things go badly wrong.

haha OK then… all the more reason to do it. open flame, fire, BBQ and July 4th.

that’s the spirit lol :beer:

curious… how are you calculating the math for the resistance additions?

More specifically if I wanted a 30% increase what value R should I add parallel?


Another possibility is that those R050 resistors are 0.05 ohms and not 0.5 ohm (a lot of 0.5 ohm resistors are marked R5/R50/R500… the R acts like a decimal point) But it does not seem likely because of that 1 ohm resistor… 1 ohms would not have much effect on two .05 ohm resistors in parallel. Also 0.2 ohms seems to be a rather common sense resistor, but usually used at lower currents than 2-3A. I’d start by paralleling in a 1 ohm resistor and see what happens.

Well… I wish I had some GREAT and exciting news to report… like a $.25 resistor doubled the LUX. But theres nothing really to report.

I clipped the leads down on the 1 ohm resistor, bent them over to a U shape and soldered one leg and then firmly but carefully pushed the other leg over to the opposite side of the resistors using a plastic tweezer. Turned the light on, and nothing… no light, no heat, no spark, no smoke, NADA. So then I just soldered the resistor leg over completely and tried again. Same result. ??? At that point (after carefully checking all the wire solder points) I just desoldered the resistor, and reverted back to the OEM circuit. Tried again, and nothing.

I think I did something to wipe out the EPROM program. Theres definitely nothing fried, burnt, overheated or shorted. Just for the heck of it I plugged in the battery charger, and I could get the light to turn on just fine but it only turned on for a few seconds, kind of dimmed slowly and then turned itself off. I could get it to do this repeatedly, so long as the charger was plugged in.

So I was hoping I could hot rod the OEM board, but no dice.

So I went back to plan A.
-I doubled up an extra 7135 driver on the Illumination supply 3.04A board, to get me into the 3.4A vicinity.
-Ditched the OEM emitter for a neutral tint T5-5000K on a 20mm star.
-Ditched the OEM 18650 cells for some new CGR18650EA in a 2P arrangement for a total capacity of ~5Ah.
-Replaced the white thermal grease with arctic silver 5.
-I was able to salvage the recharge plug, and I wired that up to the 2P-18650 arrangement so I could charge them easily with my hobby charger.

In my haste I forgot to ground out the #3 star on the driver board, so I have disco for now. I’ll have to go back in there tonight and get that fixed. I’ll post beamshots too… sit tight.

OK heres a pic of all the new stuff. Its doesn’t look like much but dam that took all afternoon. Got the modes all sorted out too so its just LO-MED-HI.