[Review] 77 Outdoors D25 Headlamp (18650)

This driver is total crap . Zero stabilization , output depends on voltage: 4.2v- 2A, but on 3.8v output already dropped to 1,4A. And it overheating fast and dropping output even more to 1A and keeps dropping …to 0,7A! :person_facepalming: Its real 10$ hi tech :smiley: I never stop wondering why Chinese engineers cant use few AMC7135…

Hhmm - the current limiting resistors can't help but maybe those parallel FET's are pretty bad then. Maybe the cost issue of the FET's because our good FET's are not cheap even in China, in fact they are almost all counterfeit there because of the high cost.

They probably have a cost cap for the driver, probably about $1 - $1.50

I may have to re-plan this - try to get a stock OSHPark driver in there. 7135's would be great - don't need hi power, better regulation, but not sure.

@Tom E, that’s inspirational. More details with progress, please.

Well… thermal control is working, but appears to be a bit conservative. The body stayed at 45°C (113°F) throughout the run. I think I need to kick that up a notch and hopefully avoid the initial big drop. I will say that when I ran this test with the stock D25, it got hot! I need to find the middle ground. Thoughts on an ideal temp?

45C looks good. Do we need 1000lm in headlamp? I think more important thing is long run time and stabilization of modes.

…where Frugal meets with Flashlight! :smiley:

If you decide to sell pre-flashed MCUs I’d be interested in a couple.

I think 1000LM would be great for the outdoors, personally I can never get enough light in the dark.

Yes . 5000lm would be great even more . But first of all you have to understand technical parameters like heat dissipation. This tiny body can not handle more than 1A. 1A is about 300lm of warm 3000k HI-CRI light. And if you need more throw , you can always use narrow angle optics

Ok, another thermal runtime test. The previous one had the temp limit set to 60°C, resulting in a body temp of 45°C. I’m guessing this is due to the poor thermal path from the driver to the body. I had calibrated the MCU’s thermal equation using room temp (21°C) and my oven at 85°C. I ran another test with the temp limit set to 70°C, which resulted in a stabilized body temp of 53°C - definitely hot, but not scalding. Here’s what the resulting graph looks like. BTW, it takes the about 12 minutes for the body temp to reach it’s max and stabilize.

I’m curious about turning off thermal management to simulate the stock driver and take temperature readings since I didn’t do that initially.

By the way, are you testing with 2 or 1 led version, D25 or D10? Better body for modding is D10…

2 LED (D25). Unfortunately that’s all I’ve got.

D10 have same driver only 1 led, in D25 leds are connected in parallel. If disconnect 1 led you will have D10 ;))

Yup. But the D10 has a “standard” 20mm MCPCB, IIRC, making LED swaps easier. And they can accept optics with a little bit of effort. But yeah, the same electrically speaking.

will a Panasonic NCR18650B (protected) fit ?

Yea it should be fine i have the single LED edition the battery tube is big. My only issue with the light is that there is no middle head strap.

Thanks Chris…I was thinking that too but I have the trusty Boruit RJ02 which came with the middle strap so I could swap headbands I guess

The single head band works really good on non heavy lights (I wanted to avoid saying light lights)

Well, with the dual I got, I swapped the LED's to T6 4C's that I had laying around, and I wired in a ATTiny85 to the stock driver, using NarsilM in 1 channel output mode. It worked pretty well. On a 35E cell, got 3.26A and about 970-930 lumens, not much drop in 30 secs, got barely warm, maybe, so handled the heat pretty well. All worked great til it stopped working...

Seems like after it heated up, something shorted out. If I loosen up the driver, it goes back to working, but as soon as I tighten it up, it shorts out again (i.e. light comes on max).

So my theory was correct about it being a simple FET channel, and wiring up the 85 with grnd, Vcc, switch and FET is all that was needed. Also I replaced the D1 diode with a 4.7 ohm resistor, and that worked well. Got frustrated with it for now - will trouble shoot it later. Need to de-solder the LED wires which are kind of a pain to thread thru the tube to the MCPCB. The wiring and positioing the 85 are all tight, so something there probably is making contact where it shouldn't.

^ talk about a brain transplant!

Wondering whether it would be possible to make a PCB for conversion from ATtiny to PIC, particularly since it would only require three (or four) traces?

Do-able but no room for it in this light. It would be better to design a driver that's a dead-on fit to the stock one, but even then, parts placement is critical because you have to have clearance for the plastic piece - there's just no wiggle room. Not many options with this light. The plastic piece is the important thing here. Probably a way to trim it to accommodate a stock size OSHPark driver, but didn't look at that.

So far what I've seen with this NarsilM on a wired in chip can work well with this light - it doesn't get a lo-lo, ramping at the low end is a little flickering - expected from low output levels to a FET though - seem the same thing with our normal FET's. I'd probably have to lower the PWM rate for these low levels - we've (maybe just TK) have done this before.

You are really limited in full modding this thing - the LED wires go thru tiny channels inside the battery tube so you can't go to heavier gauge, for the dual, not so easy to replace the MCPCB. Maybe using 2 small ones, but has to be thin as well. I want to keep the amps low, better efficiency then on just a single FET channel. I might actually remove a current limiting resistor or 2.