Thrunite BSS V4 Flashlight Review
Here’s the Thrunite BSS V4 flashlight – specifically the weapon mount version. This flashlight uses a single 18650 (included) and has Picatinny mounts!
Official Specs and Features
Here’s a link to the Thrunite BSS V4 flashlight product page.
Versions
There are at least two versions of the Thrunite BSS V4 – black, and this Desert Tan version. And there’s also the Wowtac version, which I have reviewed, too.
Price
The Thrunite BSS V4 flashlight sells for $59.95 and is available now. The Thrunite BSS V4 weapon mount flashlight bundle (as seen here!) costs a bit more – $89.95.
Amazon.com even shows some other variations (including camo and grey), so go look there! Here’s an Amazon (referral link) to get you there.
Short Review
All in all, this is really not all that different from the Wowtac BSS V4 I already reviewed. The emitter is different, of course, but the Thrunite BSS V4 weapon mount flashlight seems to be cool white only (whereas the Wowtac version was available in neutral white.) The additional bits (which add a good bit of cost to the package) are very suitable for weapon mounting this light. So that’s good, too.
Long Review
The Big Table
| Thrunite BSS V4 Flashlight | |
|---|---|
| Emitter: | Luminus SST-70 |
| Price in USD at publication time: | $59.95 (or 89.95 with the kit). It’s less on Amazon.com, too! |
| Cell: | 1×18650 |
| Turbo Runtime Graph | High Runtime Graph |
| LVP? | Yes, with switch warning |
| Switch Type: | Dual |
| On-Board Charging? | Yes |
| Charge Port Type: | micro-USB |
| Charge Graph | |
| Power off Charge Port | with cell: top four modes without cell: no modes |
| Claimed Lumens (lm) | 2523 |
| Measured Lumens (at 30s) | 1988 (78.8% of claim)^ |
| Candela per Lumen | 7.9 |
| Claimed Throw (m) | 250 |
| Candela (Calculated) in cd (at 30s) | 649lux @ 5.101m = 16887cd |
| Throw (Calculated) (m) | 259.9 (104% of claim)^ |
| Claimed CCT | Cool White |
| Measured CCT Range (K) | 6000-6600 Kelvin |
| Item provided for review by: | Thrunite |
| All my Thrunite reviews! | |
^ Measurement disclaimer: Testing flashlights is my hobby. I use hobbyist-level equipment for testing, including some I made myself. Try not to get buried in the details of manufacturer specifications versus measurements recorded here; A certain amount of difference (say, 10 or 15%) is perfectly reasonable.
What’s Included
- Thrunite BSS V4 Weapon Mount Flashlight
- Wowtac 3100mAh 18650
- Pocket clip
- Nylon pouch
- Replacement switch cover
- Replacement charge port cover (2)
- Spare o-rings (2)
- Lanyard
- Picatinny rail mount
- Hex key
- Remote switch tailcap replacement
- Red lens to replace crenelated bezel
- Manual etc
Package and Manual
Build Quality and Disassembly
Build quality is just fine here on the Thrunite BSS V4 weapon mount flashlight.
The bezel is striking. It’s easy to remove, and the light works fine without it.
This strike bezel unscrews very easily (but not accidentally).
This design on the tailcap does little to help with unscrewing the tailcap for cell swaps.
The head end has a brass button. The tailcap has a big thick double spring.
The threads on the tail are square-cut, fairly short, and unanodized.
There’s an inner tube on the cell tube.
The light isn’t designed to be used without a bezel, but the lens didn’t fall out.
This is why the bezel is so removable: There’s a red screw-in filter. The filter precludes the use of the strike bezel. Unlike the strike bezel, the red filter is flush on the front.
Size and Comps
Dimension: 146.5mm x 28mm x 25.4mm
Weight: 98g (NOT included the battery weight)
If the flashlight will headstand, I’ll show it here (usually the third photo). If the flashlight will tailstand, I’ll show that here, too (usually the fourth photo).
Here’s the test light with the venerable Convoy S2+. Mine is a custom “baked” edition Nichia 219b triple. A very nice 18650 light!
And here’s the light beside my custom-engraved TorchLAB BOSS 35, an 18350 light. I reviewed the aluminum version of that light in both 35 and 70 formats.
Retention and Carry
First, but probably not most important, is the pocket clip. This is a friction fit pocket clip, which goes only one direction, and only on the tail end of the light. So bezel down carry only.
The included lanyard fits in the tailcap loop.
A nylon pouch is included. The light will fit in either orientation, but there are no holes in either end. So the light must be removed for use.
Finally, and most important for the weapon mount aspect of the Thrunite BSS V4 weapon mount flashlight, is this Picatinny rail adapter. This is a very high-quality mounting point.
The flashlight goes into the loop there.
This isn’t a mount you’ll use off and on – it’s more permanent. That’s because these four screws must be removed fully in order to get the flashlight in and out. It’s not hard, but doing it on the fly would be unappealing.
Since you won’t be removing the light frequently from this mount, there’s little point in mentioning that no other carry options can be used while in this adapter.
The flip side of all the above is that removing or adjusting the apparatus on a weapon is very easy. That big thumbscrew is useful and easy to manipulate.
I’m not completely sure how this remote switch is supposed to mount. Anyway, here it is. I’ve seen other WMLs that have a Picatinny holder attachment specifically for holding this type of remote switch. I think this switch will fit in that type (but one is not included).
Importantly, the charge port is not blocked when the flashlight is mounted in this way. In fact, nothing is blocked when the flashlight is mounted this way. You can still swap out the tailcaps, you can still access the side e-switch, you can still swap the bezels.
Power and Runtime
The Thrunite BSS V4 weapon mount flashlight runs on a single 18650 lithium-ion cell. A proper cell is included – 3100mAh button top. However, even the shortest flat top unprotected cell seems to work just fine in the light.
The cell is installed in the usual way – positive terminal toward the head.
Here are a few runtime graphs.
Charging
The BSS v4 has onboard charging too, in the form of a micro-USB port in the head. This port is opposite the e-switch. Again, this is micro-USB. Thrunite definitely knows how to use a USB-C charge port, but the BSS V4 just isn’t there yet. It’ll be a needed upgrade when that does happen.
An appropriate cable is included: USB to micro-USB.
Modes and Currents
| Mode | Mode Claimed Output (lm) | Claimed Runtime | Measured Lumens | Tailcap Amps |
|---|---|---|---|---|
| Turbo | 2523/614 | 125s/147m | 1988 | 8.44 |
| High | 1426/634 | 130s/150m | 1361 | 2.86 |
| Medium | 350 | 4.5h | 343 | 0.52 |
| Low | 33 | 55h42m | 33 | 0.04 |
| Firefly | 0.54 | 56d | 0.5 | 0.00 |
Pulse Width Modulation
None of the modes exhibit PWM for mode management.
Here you can see a “baseline” – a chart with almost no light hitting the sensor.
Then there’s the Ultrafire WF-602C flashlight, which has some of the worst PWM I’ve seen. It’s so bad that I used a post about it to explain PWM! Here are multiple timescales (10ms, 5ms, 2ms, 1ms, 0.5ms, 0.2ms) to make comparing this “worst” PWM light to the test light easier. That post also explains why I didn’t test the WF-602C at the usual 50us scale.
User Interface and Operation
There are two switches on the BSS v4. First is the mechanical tail switch.
This tail switch is very clicky and proud but shrouded on two sides by the tailcap. This allows tailstanding while also allowing easy access while wearing gloves.
Next is the indicating e-switch on the head. Note that this one has a metal cover. (Metal, or plastic, either way, it’s not rubber and soft.)
Thrunite makes a good e-switch, and this one is too. There’s even an indicating feature in the center.
A third option, and one not seen on previous BSS reviews, is this remote switch. This is a complete tailcap replacement.
Here’s a user interface table!
| State | Action | Result |
|---|---|---|
| Any (Unlocked) | Click Tail Switch | Turbo |
| Any (Unlocked) | Tap Tail Switch | Momentary Turbo |
| Off (Unlocked) | Click Side Switch | On (Memory Mode (LMH only) |
| Off (Unlocked) | Hold Side Switch | Moon |
| Moon | Click or Hold Side Switch | Off |
| On (except Moon) | Click Side Switch | Off |
| On (except Moon) | Hold Side Switch | Mode advance (LMH) |
| Moon | Long hold Side Switch | Lockout (Switch turns red when clicked) |
| Lockout | Long hold Side Switch | Unlock |
| Any (Unlocked) | Double click Side Switch | Turbo (Really it’s “previous mode then Turbo”) |
| Any (Unlocked) | Triple click Side Switch | Strobe |
LED and Beam
Unlike other BSS lights, this Thrunite has a Luminus SST70 as the emitter option. The reflector is still smooth and deep.
As stated above, there’s also a red filter option.
LED Color Report (CRI and CCT)
The (single!) emitter is driven pretty hard at over 8A on the highest output level, and we can see the CCT creep toward the blue in that case. Otherwise, around 6000K for a WML isn’t all that unusual.
Beamshots
These beamshots always have the following settings: f8, ISO100, 0.3s shutter, and manual 5000K exposure. These photos are taken at floor level, and the beam hits the ceiling around 9 feet away.
Tint vs BLF-348 (KillzoneFlashlights.com 219b version) (affiliate link)
I keep the test flashlight on the left and the BLF-348 reference flashlight on the right.
I compare everything to the KillzoneFlashlights.com 219b BLF-348 because it’s inexpensive and has the best tint!
Conclusion
What I like
- The full package with Picatinny mount is great
- Red filter seems to be very high quality
- Complete package with high capacity 18650
- Good user interface
- Nice remote switch
What I don’t like
- No non-strike non-colored bezel option
- Micro-USB charging seems outdated
Notes
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