ASTROLUX MF01 Mini - common issues thread

Hi everyone I want to post some info here about the most common issues with these MINIs and some solutions how to fix them.

1. Incorrect Voltage measurement and LVP kicking in

I asked Lexel about the problems with voltage measurement (since he is the one who designed the board) and he was very kind in walking me through the problem and showing me a solution. Some of these MINIs measure the voltage bang on, some measure up to 0.4V less. If they measure the voltage to be 0.3V less than it really is, the low voltage protection will kick in 0.3V sooner and turn off the light. This is caused by the fact that the manofacturer has changed some components in Lexels original design for cheaper alternatives: mosfet, inductor and very likely a diode (Lexel wasnt sure from the picture about the diode). The easiest way to correct this is to flash the flashlight. Manual for doing so can be found here:

You will need to do following changes to the code:

_in the hwdef of the Anduril files you needx to adjust this code

// average drop across diode on this hardware
#ifndef VOLTAGE_FUDGE_FACTOR
#define VOLTAGE_FUDGE_FACTOR 5 // add 0.25V
#endif_

each +1 adds 0.05V

I asked ToyKeeper if she plans on adding a feature that would allow voltage calibration by clicking in the menu. She told me its not realistic at the moment. As is the Anduril code barly fits onto the chip most flashlights use. Thats why there is eather check version or muggle mode option but not both. Some flashlight like emisar have switcher for larger chips, but most havent.

2. Flashlight throttling down after few seconds from max ramp

These lights have a tendency to throttle down from max ramp after 20-30sec to about half the visible intensity. This doesnt seam to happen as fast in turbo mode when the lights get much hotter. I asked Lexel about it and he gave me this explanation (I copied only the most important parts):

_It’s not a problem it’s a sign that the user didn’t calibrate the temperature setting.
Any Bistro 3 channel driver has this behavior and no one ever complained about it.
It’s a known fact that FET+n+1 drivers heat more in regulated mode than while FET only active (smaller drivers are always more affected than big ones).
FET+1 drivers have only a fraction of heat on driver compared to a full bank of AMCs, also a 7 LED light has low LED voltage
You can simply eliminate this by flashing a firmware not using the AMC bank stepping back to FET+1 2 channels.
Generally a setting of like 45°C is way too low with new temperature code, I usually use 55 or 60°C (LiPo is 70°C upper limit)._

Easiest solution here is to calibrate the light to the correct room temperature and set the temperature limit higher. Let it cool down to room temperature (like about 30min) and calibrate the temperature to the actual flashlight/room temperature. Than set the temperature limit to a higher value like 60C (max 70C). As I understood this some components on the driver get very hot during voltage/current regulation in ramping and on max ramp they get so hot that they cause the driver to lower output power. This effect is a bit more noticable on this light because is has very small and a bit packed driver board (they had to fit those components in somehow).

EDIT 30.11.2019:

User man of light designed a great little copper insert that replaces the original plastic driver cover and creates a thermal bridge between the AMCs and flashlight body. This copper MOD will greatly increase the time before the light starts throttling down in ramping once you set ramp level. Here is a link to his project, its simple jet very clever MOD and he is trying to secure a small batch of these custom made for us, go check his thread for more info on this project, prices etc. Link:

s. I am very gratefull to Lexel and Toykeeper for entertaining my silly question (especially to Lexel who walked me through details).

Hi, what i can say is that i calibrated the flashlight very correctly,i set te temperature limit to 60 and even more degrees Celsius and the stepping down is present no matter what. But i noticed that when i ramp a few times up again it strats to hold the max ramp longer and eventually it stays there for a few minutes. Another thing i noticed at the same lumen level (i tested with 1800lm) with fresh battery 4.2v it strats to step-down after 5 to 10 seconds, but with little bit drained battery 3.8V and lower it holds those 1800lm for a few minutes. Another thing i noticed that when the flashlight hold the max ramp when i touch it it steps down a bit and when i leave it it stay on that new level (it is exactly opposite of my other lights in wich the touch cool them down and increase the output). At all very strange behaviour,so the explanation about incorrect tepm set isn’t the case here, it is something else.

Hi eneorors. The way I understood it is this: the chips responsible for ramping drop a lot of power during ramping. At max ramp they should drop the most power. They get very hot very quickly. There are several of them on the driver and they are very close together on a small board. This heat doesnt get transfered to the flashlight body as well as the heat from LED emitters. They do descipate the heat slowly, but there is really nothing we can do about it(I dont think there is termal paste between them and flashlight body.

But this isn’t happening only in max ramp it happens in 1000lm too, it rapidly step down to about 500lm.To me it doesn’t seem that heath is the trigger.

Thank you Dr.Phillip for creating this thread and collecting all the Information to the mentioned issues of the MF01 mini. Also thanks to ToyKeeper & Lexel for the analyses and Infos.

To the 2nd Point (stepping down after few seconds): Its not only from max ramp, it steps down from any output level, from about 500 - 2000 lm, for example if you just switch on in last memory mode of about 1000 Lm. As already explained by Lexel, if the FET is not active, the AMCs are getting to hot very fast and therefore is this step down.

I’ve already calibrated the thermal setting exactly this way , and anyway after switching the light on in a output level of about 1000 Lm it takes 10-15sec in my case till the step down begins. It goes quite quick to abot 500 Lm.

I started thinking about a mod to heatsink the AMCs to the host. Therefore I would replace the plastic cover of the driver board by a copper manufactured ones wich would have a good contact to the AMCs with thermal grease. Also the contact to the driver pcb (GND surface) and the host should be good to transfer the heat. Very important would be a safe insulation to the positive pole and the other parts of the driver boards, to avoid short circuits and conductive contacts. Maybe Lexel could estimate whether such a modification would be worthwhile to stop the step down or significantly improve.

Let me try to explain this part. The chips you are refering to are AMC7135 current regulators. These accept voltages from around 2.7v to 6v and what they do is only allow around 0.35A (350mA) to pass through them. The mini has 3 channels controlled by the MCU. Channel 1 uses a single 7135 chip as seen in the pic below.

This is pretty low current so it doesn’t produce much heat and the brightness range is small. It makes for a nice moonlight level and up to maybe 150 lumen.

Now channel 2 uses the 6 chips plus the 1st one. So now you have 7 chips that allow up to (.35 x 7) 2.45A. This is what the top of the ramp is set to. So all 7 chips do produce some heat, but you can see the ground tab is soldered to the outer copper ring and that is pressed against the battery tube. That is your heat path (red arrows). This looks pretty decent. Actually, the battery tube does not contact the driver so that heat is not being drawn away.

The temperature sensor is built into the MCU on the other side of the driver board as seen below.

The way heat gets to the MCU is through the 8 metal legs.

There is definitely no thermal paste on the 7135 chips as they are soldered.

On Turbo, all 7 chips are not used and all the power goes through the FET. You can see there are a lot of vias around it to spread the heat to the other side of the driver.

I really don’t know if this quick step down from the top of the ramp is a standard problem of the 7135 chips getting hot and heating the MCU much quicker than the body or if something strange is going on in the software.

I believe the 7135 chips may not have to shed as much heat at lower voltages. If so, then that might explain why the lower voltage allows for longer runtime before stepping down. Maybe there is some unknown thermal path between the 7135 chips and the MCU that is causing the problem and this mystery path is not between the FET and the MCU which is why Turbo does not step down early.

IDK, it’s a bit of a mystery.

It sounds like this step down should be noticeable but I have not noticed this step down. I will look again tonight. I have not calibrated my light at all.

Thank you JasonWW for extending and correcting my somewhat not exact answear. Now we have a full explanation.

The mystery is still afoot. Lol

Interesting topic. So which type of driver will run cooler at let’s say 500 lumen, a FET+7+1, FET+1 or linear-FET driver?

Do you mean in a MF01 mini?

I’ll assume you mean on the MF01 mini. Man, that’s a tricky question with a lot of parts. I can only answer parts of it.

First we need to figure out how much amperage is needed to put out 500 lumen. Let’s make an educated guess based on the 6500K SST-20 Djozz tested and say 1.5A.

With the FET+6+1 (mini driver design), the FET does not come into play. You are using the 7 total 7135 chips (2.45A) with maybe a duty cycle of 61% (I don’t know if the duty cycle is directly related to output percentage, but let’s say it is).

With the FET+1 we are using the single 7135 chip at 100% duty cycle and the FET at maybe a 12% duty cycle (based on 100% drawing 20A).

I’m not sure what you mean by a linear-FET driver. Sorry

So now we would need to run them and use a thermal camera or temp probe to see which gets hotter. For this, I have no idea. People rarely talk about driver heat because it’s usually a non issue.

We would need to talk to someone like Lexel who makes drivers and has a thermal camera. Maybe Texas_Ace, Toykeeper or Tom E know about the heat production of these components at these operating levels?

Let me see if’n I understand how the three channels are set up.

Channel One is a single 7135 (so, about 0.35A max).
Channel Two is seven 7135s (about 2.45A).
Channel Three is…what? Direct-Drive FET? Or what? Max (battery-dependent) current is?

At that level you won’t really have an issue with heat from the driver in either setup. As long as the driver has some kind of contact with the body of the light it should be fine.

That said, a PWM FET will always run cooler then a 7135 or linear setup. Properly setup they will produce virtually no heat.

You can calculate the heat from the linear setups (this includes 7135’s) but it boils down to that fact that the total heat they need to burn off to maintain regulation will be the same no matter how you do it, 7135 or linear FET.

So does the duty cycle of a single 7135 chip have any effect on the heat it puts out?

I was thinking the FET didn’t generate much heat, but we’ve seen some cheap ones burn up with high amperage running 100%. So would the heat it puts out be dependent on duty cycle?

In the case of the 7135’s the duty cycle will increase the heat simply because you are also increasing the current / power.

With the FET’s, a good one should have basically no heat at normal power levels (yes, it technically does produce some heat as all FET’s have some resistance but just not enough to really matter much for anyone asking a question like this). On hot rods where we are driving 10-20A, then the FET can produce some heat if it is high resistance and even die. The only cases that come to mind of the FET dying were at currents of ~20A.

Although this is more a case of simply pushing the FET past it’s design specs then it getting too hot directly.

The duty on the FET will increase the heat since it also increases the total power / current but technically it will actually get a bit more efficient when you reach turbo 100% duty as you no longer have the switching losses. Once again though this is a case of if you have to ask, then you most likely don’t need to worry about this as it will only matter in fringe cases.

Quick question, what exactly is a linear-Fet driver? Is that a thing?

I don’t know it exactly as well but I found this:

High efficiency LED driver. All modes (except moon) are implemented without PWM , linearly, using a current source based on a MOSFET transistor, which in practice means 1.5-2x longer work time at low brightness levels compared to classic PWM drivers keying the AMC7135 current sources or transistor.

The controller has a turbo mode (current 8A), about 3200lm for 4x XP-L, implemented by a MOSFET transistor, with hardware stabilization of the upper current value.

Parameters:
• linear5A current source implemented on MOSFET RDSon 0.95 mΩ transistor controlled from ATtiny85V with feedback
• modes (brightness levels) implemented without PWM, with maximum LED efficiency
• diameter 17mm - flashlight standard
• supply voltage range 2.8-4.5V
• power supply: 1x 18650 Li-ion cell, preferably without protection
• maximum LED current 5A, in turbo mode 8A (limited by the capacity and battery charge level)
• full current stabilization at Vf LED + 0.1V supply voltage, with the latest brand cells to be used 80-85% Li-ion capacity
• no PWM , flicker, noiseless operation
• total efficiency 2.8-4.5V power range is over 90%

and

Thanks for that. It’s all much clearer to me now. :beer: