First question noob so please be gentle.
… Only been stalking the forum up till now…
My favourite “work” light has died. Milwaukee M12 T Led.
It ugly but super useful, any angle head, magnet, nice wide work beam, and I have loads of battery units.
It’s just on/off. No modes
The switch works and puts 12.6v (battery voltage) out of the drive unit when the switch is open.
The led is suspect. About 16 ohms in both directions.
The led unit is fixed direct to the Aluminium head unit as heat sink ( I assume )
The led emitter is a tiny dome on a square mount that I think is 3mm square ( but it could be 2.5mm)
Any advice on how to fix, or even upgrade.
Comfortable soldering… But don’t know what led or where to get in the UK .
Big thanks. Phil
Have you checked what voltage is at the LED? You need to work out what LED it is, or at least the voltage it runs at. It’s most likely a 3V LED, but it could be 6V.
(Or are you saying there’s 12V at the LED?)
It could be easier to just gut everything and fit a new driver and LED.
Once you determine the LED voltage, you could swap the LED, either by installing a new LED which is already reflowed onto an MCPCB, or by reflowing a new LED onto the existing board. To do the latter, you’d need to determine the footprint of the LED, whether it is a 3030 or 3535 LED or whatever, then buy an LED with the correct voltage and footprint, and reflow.
If you buy an MCPCB with an LED already on it, it will probably not be the same size (diameter) as the MCPCB used originally, so utilizing the screws to screw down the new MCPCB might require the use of a plate with some holes in it, i.e., a clamp of sorts, or you could drill and tap some new screw holes in the heatsink, or thermal epoxy could be used to secure the board, or just regular super glue would probably be fine and not super permanent, you could still pry off the board, and dissolve residue with acetone.
I suspect it is not the LED at fault, but the driver. If you were to try a new LED and you still don’t get modes, you may want to repair or replace the driver. Important to note is that the M12 battery does not feature any integrated low voltage protection, as this function is performed by the Milwaukee tools, according to stuff I’ve read online. I can not advise you on how to repair the existing driver. What driver you could use as a replacement will depend on how much space you have to work with within the host, how big is the existing driver cavity. If you need more space you could hot glue or otherwise attach a small external enclosure or shrink wrapped PCB to the body, above the handle on the side about where the Milwaukee logo is, or on the back side of the swivel head, or extend it out the front of the driver cavity as far as required by removing the switch boot and possibly enlarging the hole there.
Thanks all.
Attached, pic of driver circuit that is putting out battery voltage of 12.6 direct to the led.
This suggests that either the led is 12v (unlikely)
Or, that the driver is faulty… But if it puts out 12v. It might have burnt out the existing led unit.
To test… I briefly put a 18650 (3.6v) across the led and it lights…
So your assumption about broken driver is likely good.
As a noob… And it seems that modern drivers have multi function OS that will probably be incompatible with the units click on click off switch.
Any suggestions on how to source a buck driver that can step down battery voltage… And presumably offer some current limitations,?
The selection of 3S / 12V input drivers is not great afaik. KD has a few. Convoy doesn’t have any 3s drivers, I think. There are some random 3s drivers on AliExpress. This one could work, but no LVP.
There is a pololu buck regulator with trimpot adjustable LVP and another trimpot for voltage ADJ, but it’s probably too expensive to recommend relative to just buying a new M12 light from ebay. But if you wanted dimmer knob control, it would be one way to get it. I think what would work for the control scheme is to wire a 10k pot in series with the onboard 50k trimpot. This would allow for fine enough control over the relevant voltage range using a single turn external pot. A 10k PT-15 pot and knob could be used. PT-10 is smaller, but I think the knobs might be more delicate.
Let’s see, what’s a cheaper option…? The 3 Amp MP1584EN based buck boards would work. These have an enable pin that can be pulled low to implement LVP. The same pot control scheme can be implemented as with the pololu regulator, although I do not know what value of pot to use.
Another way to implement LVP would be to use an LDO’d or zener’d FET driver as the switch. Behind the driver will be the DC-DC regulator. The options to select for the driver would be: 6V LVP, and custom firmware with a single 100% mode. You could get the Zener option if you want to use a clicky switch, or LDO option for e-switch. The “ramp” functionality of the LVP is less than ideal. Mtn might alter it upon request so that there is no ramp, otherwise someone on BLF might help to customize a firmware and it can be flashed onto the driver.
A low voltage alarm could be used rather than an LVP cutoff, such as this one.
Hey, based on that date code on the driver board, today is its 12th birthday!
Are you sure you’re getting 12V to the LED? Did you test the voltage at the LED or at those two unused solder pads marked LED +/- at the top of the pic? (Edit, I see now the LED wires connect to the “unused” pads on the other side of the board, but please still verify the voltage).
Or incorrect measurement. @PhilSpectrum said he attached 18650 directly to the LED and it lit. So it has to be a 3V emitter, and under 12V it would shine like 1000 suns (not for long).
In that case I’d guess a component failed and it isn’t stepping down the voltage to the LED. You might be able to spot a bad component if you remove that white coating. Please post another pic if you try that.
It doesn’t look like that driver has LVP. M12 batteries rely on LVP in the tool. I have M12 tools (not this light though) and would like to build a light using the batteries but I haven’t found a good solution for a driver with LVP.
Aliexpress would probably be your best bet for a driver. Don’t discount using a flashlight driver either- I’ve done that in some floodlights outside on the house- you just need to make sure the driver is insulated and doesn’t short out on anything. You’d need to change the switch if the driver has multiple modes. Edit: you should be able to change modes by placing a momentary switch to disconnect the power between the normal switch and the driver.
