Haven’t had too much time to play with the D1S, but I’m very impressed with the heat handling. Hotspot is around double the brightness of my Convoy C8. Will post a mini-review when I get the time.
Wow, those beam shots remind me of the difference between my Olight M3XS-UT and my L6. It will be interesting to compare the D1s to the Olight when it arrives.
The FET essentially allows for direct drive, so as the cell dies the output drops. It’s not about the FET itself, it’s about the capability of the cell.
Yes, the 219C will have a lower Vf and allow for more current draw from the cell used, it will also increase heat and lower run time. The XP-L2 emitters are also low forward voltage and produce much more light out the front.
Protected cells generally don’t fit in the Emisar lights.
FET-based drivers are essentially direct-drive, so the output on turbo depends on where the battery’s voltage sag curve meets the emitter’s Vf curve. The battery may be at 4.2V, but that value drops as amperage goes up, and it drops as remaining energy goes down. The emitter’s voltage starts at around 3V, but it rises with amps and temperature. Where the two curves meet is what happens in direct drive.
A low-amp cell sags more than a high-amp cell, so the curves will meet at a lower amount of current, and emit less light.
Lower Vf is not always a good thing. In particular, it is strongly recommended that you do not use a 219c emitter with a FET-based driver. The curves meet at such a high amperage that it kills the emitter. This can be avoided by using a very saggy low-current cell, but then it’s typically somewhat bad for the battery instead. It can also be avoided by using several 219c emitters per cell, but even then it has been known to turn emitters into smoke.
The bad-for-the-emitter vs bad-for-the-battery thing is similar to going down a mountain in a car. Riding the brakes wears out the brakes quickly, but generating resistance by putting the engine into a lower gear is hard on the engine. The brakes here are analogous to the LED, while the engine’s gearing is analogous to battery choice. The difference between battery voltage and emitter voltage is the slope of the hill. Does that make sense at all?
I haven’t tried it, but one potential option for safely running a 219c direct drive would be to use a LiFePO4 cell. Instead of going from 4.2V to 2.8V, those are more like 3.6V to 2.8V. It might work well for low-Vf emitters without having to worry about damaging the LED or battery.
I received my D1S today and used it for a hike this evening. First impressions are quite positive: tons of throw, lightweight and compact (but a large head), and the price is certainly right at $40 or less. The ano is very rough compared to the D1 and had rubbed off in a couple of spots. I like the tint of the 4000K emitter, which goes nicely with my Wizard Pro warm for night hikes. Time will tell whether it can convince me to give up the flat regulation and longer battery life of the Manker U21, which is now slated for an emitter swap for sure.
Note: when I received the light, the thermal limit was set to an internal temperature of something like 40°C, which translates to about 30°C at the head. That meant the light throttled down almost immediately on turbo and was at practically moonlight output by 10 minutes trying to maintain such a low temperature. I used the thermal config to set the limit to 71°C (~60°C at the head), which is pretty toasty but largely eliminates throttling. In the winter it will never actually get anywhere near that hot when used outside anyway. Here’s a quick plot of the head temperature at the original setting with a shift back to turbo at 10 minutes.
Interesting. The default sounds like it was too low, but that’s why it’s configurable. In my testing, the default didn’t really try to reduce the temperature at all. I think this is mostly just random variation in the MCU’s internal sensor, which isn’t calibrated. I get very different temperature readings from one attiny to the next, in identical environmental conditions.
I ordered the 4th and did not receive any updates until I sent him an email via reply to the original order confirmation email. He replied immediately with tracking info but that has not been updated since …………
November 12, 2017, 11:42 am
Processed Through Facility
GUANGZHOU EMS, CHINA
Your item has been processed through a facility in GUANGZHOU EMS, CHINA at 11:42 am on November 12, 2017.
Origin Post is Preparing Shipment
November 9, 2017, 6:22 pm
Acceptance
CHINA
I was going to give it at least 3 weeks before getting restless