[Review] Sofirn C8G ( XHP35 HI, 1 x 21700 ) - Output and Regulation Tests, Comparison Beamshots

The Sofirn C8G was sent to me from Sofirn's Official store in Aliexpress.

The flashlight comes in a simple cardboard box.
The accessories included in the Flashlight + Battery Kit are the following:
MicroUSB cable, adjustable wrist strap, 21700 Sofirn-branded battery, li-ion charger and two spare o-rings.

Additionally, there is also a simple 18650 to 21700 adapter included.

The C8G comes with glossy black anodization.
It's operated using two switches, a mechanical in the tail and a side e-switch.

The e-switch is covered by a semi-translucent boot and has two indicator LEDs installed in it.

The tail switch is using a dual spring setup.

Here's the switch fully taken apart.

It's worth noting that the switche's PCB has two unpopulated slots for diodes (probably LEDs).

The boost driver is using a short, thick but quite soft spring.

Here's a closer look at the driver's circuitry.

The XHP35-HI is CW tinted and is seated inside a smooth reflector.
Thanks to the centering ring, the emitter is nicely centered.

The charger has an indicator LED installed (Red: Charging, Green: Full or Disconnected)

After a full charge / discharge cycle, I measured 4111mAh of real capacity in the included cell.

User Interface

The C8G is using a dual switch setup.
The rear switch is only used to turn on/off the flashlight, while the side-switch is used for mode switching.
Two mode groups are supported: Stepped modes (Group 1), Ramping (Group2).

Here's all the supported actions:
Turn on / off: Single click of the rear switch.
Mode Cycle: Single click ( Low > Mid > High > Low > ... ) - when in Group 1.
Ramp up/down: Long press - when in Group 2.
Mode-Group change: Quad click.
Turbo: Double click.
Moonlight: Double click while in Turbo, or press-and-hold the e-switch while powering on the flashlight.
Strobe: Triple click.
Blinky mode cycle: Long press ( Strobe - Beacon - SOS).

The flashlight comes with regular mode memory, while the LPV is activated at 2.8V.

Output and Regulation

In order to take my measurements I used the RD DPS5020 bench power supply.
Here's the measured lumens (at turn-on) along with the current drawn in each power level.

Turbo is pushing around 1650 lumen, which is lower than the advertised 2000.
The lower output is probably limited by the capability of the circuit to efficiently boost the voltage from 4 to 12V.
Also, the power consumption at Moonlight is quite high, which is quite typical for 12V boost drivers.

And here's a V / A graph to view the regulation of each output level.

The the respective V / W graph.

What we can see from the graphs:

  • Turbo isn't regulated, at the current draw is directly affected by the input Voltage.
  • When the battery is at < 3.5V, Turbo won't activate at all in order to prevent over-discharge and high voltage sag.
  • High and Medium are fully regulated down to 2.9V
  • Low and Medium are fully regulated down to 2.8V

And here's a ~20 min thermal regulation graph for Turbo mode.

What we can see:

  • Maximum output is sustained for 30 secs.
  • After the first 30 seconds, output gradually steps down to 1075 lumen.
  • 1075 lumes are sustained for 3:30 mins.
  • After the 4 minute mark, there's another gradual stepdown to 790 lumen, which is completed at 8mins.
  • Once stepped down to 790 lumnes, the flashlight's temperature stabilizes and that output level is fully regulated and sustainable.
  • (Not shown) Turbo can be re-engaged at any time.

Outdoor Beamshots

At 12m

At 35m

At 400m - The white dot is a van. Not clearly visible in beamshot, but it's easily recognizable in real life.

And the comparison shots at 220m (captured at Dusk)

Sofirn C8G - Sofirn C8T

Lumintop GT Mini - Sofirn C8A

Fantastic review again! The shortcut to low is something a lot of these dual switch lights are missing, very glad to see if here.

Thanks for you kind words.
Having a direct shortcut to moonlight from off is good, even if two buttons are involved.
At first I thought that moonlight was only accessible through Turbo :slight_smile:

That power chart is a great way to show lvp and step downs all at once, among other things. And the only thing I wish they’d add to the UI is hold for momentary Turbo when on.

Great review. I would also be interested how the capacity of the battery compares to the 4000 mAh rating. I just recharged a sofirn 18650 that shut off (LVP) in my Thorfire TK18. I didn’t do a full test, just re-charged, but it only took around 2000 mAh to charge it. Not particularly impressive for a supposedly 2800 mAh battery.

I have just started a discharge test in the included battery.
It should be ready in 4 hours or so!

Cool! :+1:

Just finished the capacity test.
The cell was discharged @1000mA using an Opus BTC 3100.

As seen, I got 4111mAh of actual capacity which means that the manufacturer's rating is correct (and maybe a bit underrated :D )

Thanks for this review.

This light should at least deliver 2K lumens on turbo when drawing 8+A at the tailcap (see XHP35 output and death test + PWM efficiency test by Texas_Ace). Obviously there are some “wrongs” with it, like non-bypassed springs or lack of high current ones (losses), tailcap switch of unknown quality (possible losses) and a driver which is completely unregulated on the highest mode (sucks).

Pretty sure it is not underrated, unless that Opus charger is fitted with a power supply of around twice the rating of the stock one and uses the latest firmware it will score too much capacity.

That cell is more than probably a rewrap of the Lishen LS21700SA cell (check this review).

According to a private message I received from Sofirn, the C8G weighs 163 grams without battery (which means something like 232 g with battery). That’s twice the light-only weight of the Nitecore E4K, slightly heavier than the Fenix TK22. I hadn’t seen any reviews mention the weight so I asked them; if someone who actually has the light would like to add their measurement that could be nice.

C8G weight w/o battery: