[Review] 77 Outdoors D25 Headlamp (18650)

As I laid in bed trying to sleep last night, I realized that I lied :frowning: I usually talk about this in terms of normal vs reverse threaded. These are reverse threaded… so they unscrew going clockwise :person_facepalming:

I agree, I think I would have liked the D10 better due to increased mod-ability. Those internal “cooling ribs” are actually channels for the LED wires to run through without interfering with the battery. I doubt they’re intended for cooling, but I’ve been known to be wrong on occasion. :smiley:

No prob. I tried reversed early on, but I probably already had tightened it up, so didn't try hard enough.

Edit: took all of 2 secs to loosen the end cap now - CW, reverse, etc. .

So I see the driver and the issues - tight space, plastic ring it fits in, switch on the back side.

Looked carefully at it - probable a PIC, SOIC-8, Vcc on pin #1, switch on pin #2, FETs on pin #4, and GRND on pin #8. And that seems to be it. The FETs are two in parallel, 3 pins, output goes thru a bank of parallel current limiting resistors.

So, 4 wires, that's all. I'm thinking of removing the MCU, using an 85 in it's place and hand wiring up the 4 pins needed. Should be enough spare room on the driver. Dunno how well it will work. I'll probably replace the 'D1' diode they have with a 4.7 ohm resistor which the 85 typically needs.

These are the tools I used/tried:

It lives in pieces!

The driver:

The (my fault) damage:

I'll sand down the end cap to bare - should mostly hide the scratches, not too concerned about them - this light will get used.

NarsilM has one channel support, so should work - might jumper the resistor bank though for more power, or leave as is since normally I don't need power so the lower the max amps, the more efficient it should be.

This pic datasheet on page 4 shows the pins where Vcc and Vss are: https://www.mouser.com/datasheet/2/268/PIC16(L)F1831318323

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!