Amutorch BT35 LEP

Specifications

Brand/model Amutorch BT35
LEP Shine through LEP module
Maximum lumens 370 lm
Maximum beam intensity 470,000 cd
Maximum throw 1,371 m
Battery 1*18650 Li-ion
Onboard charging No
Material Aluminium
Modes 2
Blinkies No
Reflector No
Waterproof IP68
Review date September 2022

Introduction

Neal asked if I would like to review anything in his store. Out of everything in his store, and he has a lot of unique and rare torches, I asked for the Amutorch BT35 because it looks like a cool pocket sized LEP torch and I want to learn more about LEP torches.

The Amutorch BT35 is a pocket sized tactical Laser Excited Phosphor (LEP) torch that produces a lovely white beam.

I am new to the world of LEP torches. My understanding is that a LEP torch has a laser that excites a layer of yellow phosphor which then emits an intense light. There are mirror style and shine-through style LEP modules. The BT35 has a shine-through design where the beam goes through a biconvex lens.

This torch was sent by Nealsgadgets for review. I have not been paid for this review nor have I held back my opinions of this torch.

Packaging

The BT35 came a plain cardboard box with an Amutorch sticker on top. The torch was well protected inside bubbble wrap and foam.

Amutorch BT35 packaging front Amutorch BT35 packaging inside

The following was included in the box:

  • Amutorch BT35 LEP
  • Cigar grip
  • Tactical ring
  • Two spare o-rings
  • Instructions in Chinese
  • Two plastic tailcap rings (not included in my sample)
  • Amutorch 18650 3200mAh (optional, not included)
  • Charger (optional, not included)

A few torch enthusiasts have reported that their Amutorch BT35 came with two plastic rings that screw onto the tailcap. This allows the torch to tailstand and helps prevent accidentally pressing the button.

Amutorch BT35 packaging foam Amutorch BT35 accessories

Amutorch BT35 grips Amutorch BT35 user manual

Torch in use

The Amutorch BT35 fits perfectly in the palm of my hand.

Amutorch BT35 in use 1

The forward clicky button gives a satisfying click and it is easy to use.

It is a little bit slippery due to having a smooth tube but both the head and tailcap add plenty of grip.

The cigar grip can help prevent the torch from falling out of your hand and it also helps stop it from rolling around on a flat surface.

Amutorch BT35 cigar grip

The tactical ring can be attached between the tube and tailcap. It has a deep carry pocket clip one one side and a ring on the other. The ring allows you to operate the torch and a firearm without it necessarily getting in the way. However, the beam produced is quite narrow so it may not be great for scanning an area at short range.

Amutorch BT35 tactical grip

The tailcap has a thread near the button for one of two plastic rings to be attached (not included with my BT35). The rings allow the torch to tailstand and help prevent the button from being accidentally pressed.

Build quality

The Amutorch BT35 is constructed of aluminium. The body has a matte black anodised finish on both the outside and the inside. The torch feels smooth and there are no sharp edges.

Amutorch BT35 front Amutorch BT35 left

Amutorch BT35 back Amutorch BT35 right

The bezel is screwed onto the head without glue and there are two o-rings to help prevent water from getting in.

Amutorch BT35 lens top

Glue was used to connect the tube and head so that the tube does not accidentally unscrew while unscrewing the tailcap to insert a battery.

The rubber switch boot feels firm. It is not mushy. The tailcap has a thread to allow one of two plastic rings to be attached to allow the torch to tailstand.

Amutorch BT35 button

There are four fins around the LEP module to help dissipate heat.

Amutorch BT35 head

Thin square cut threads on the tube came well lubricated and they allow the tailcap to turn smoothly.

Amutorch BT35 threads

There is a brass retaining ring with two notches in the tailcap holding down a PCB for the tail switch.

Amutorch BT35 spring

LED, bezel, lens and beam

The Amutorch BT35 has a shine-through LEP module.

I unscrewed the bezel from the head to reveal: an o-ring at the base of the threads, another o-ring in the bezel, a flat glass lens, a plastic ring, and a biconvex lens with an anti-reflective coating on both sides. The plastic ring in the head helps keep the biconvex lens separated from the protective glass lens.

I was not going to open up the head but u/101marty on reddit made a post asking for help on r/flashlight. Their BT35 produces a beam with an unusually wide spill and multiple rings. I would recommend asking Amutorch for a replacement if your BT35 produces such a beam. It should produce a narrow white hotspot with almost no spill.

Amutorch BT35 lens Amutorch BT35 phosphor

I have taken Correlated Colour Temperature (CCT) and Colour Rendering Index (CRI, RA of R1-R8) measurements with the torch positioned one a metre away from an Opple Light Master Pro III (G3).

The CCT is about 6300K and the CRI is around 60.

The Delta u, v is slightly positive (almost pure white to my eye).

The beam has an intense white hot spot with almost no spill.

Mode CCT (K) CRI (Ra) x y Duv
Low 6085 59.5 0.3186 0.3545 0.0130
High 6518 62.4 0.3109 0.3404 0.0098

Calculate Duv from CIE 1931 xy coordinates

Dimensions and size comparison

Dimensions

I took the following measurements using digital callipers.

Measurement Unit (mm)
Torch length 132.1
Head diameter 32.2
Tube diameter 25.7
Tailcap diameter 25.9
Tailcap thread diameter 21.2
Tailcap thread length 5.1

Weight

I took the following measurements using a digital scale.

Weight Unit (g)
Torch 116.3
Battery 46.0
Torch with battery 162.3

Size comparison with its competition

I do not have any other LEP torches of a similar size so I have compared it with two other 18650 EDC torches.

From left to right: VezerLezer ED10, Amutorch BT35, SPERAS EST

VezerLezer ED10, Amutorch BT35, SPERAS EST

From left to right: VezerLezer ED10, Amutorch BT35, SPERAS EST

VezerLezer ED10, Amutorch BT35, SPERAS EST

User interface and driver

A mechanically forward clicky tail switch can be half pressed to momentarily turn the torch on and switch between Low and High modes.

State Action Result
Off Half press Momentary on (mode memory)
Off Double half press Cycle (Low, High)
Off Click On (mode memory)
On Click Off

Low voltage protection

There is low voltage protection. The torch turned off at 2.92V.

While testing for LVP, I decided to remove the head from the tube so that I could easily access the driver. The head had been glued to the tube. I squeezed the tube with vice grip locking pliers and a piece of rubber in one hand. I then twisted the head with my other hand. The glue broke and the head unscrewed from the tube to reveal yet another o-ring on the tube threads that were previously hidden.

PWM

I did not notice any visible PWM (flickering).

What I like about the UI

  • Simple to use. I love forward clicky tail switches!

What could be improved

  • The ability to disable mode memory and instead start on Low would be nice.

Batteries and charging

Battery

The Amutorch BT35 has two small springs at each end for one unprotected flat top 18650 3.7V Li-ion cell.

I successfully used an unprotected flat top Samsung 30Q 18650 cell.

I tried to use a protected button top 18650 cell but it was too long.

Charging

There is no built-in charging.

Performance

Specifications:

High Low
Light Output (lm) 370 100
Beam Intensity (cd) 470,000
Beam Distance (m) 1,371
Runtime 1h20min 4h30min

Amutorch used an Amutorch 18650 3200mAh cell for testing.

Lumen measurements

I used a UNI-T UT210E clamp meter to measure the current at turn on.

Mode Amps at start Specs Lumens @turn on Lumens @30 sec Lumens @10 min
Low 0.70 A 100 107 102 101
High 2.30 A 370 263 321 195

Standby drain

There is no standby drain. This torch has a mechanical tail switch.

Runtime graphs

I used my own DIY lumen tube with a TSL2591 sensor and forked bmengineer’s project RuTiTe to record runtimes.

Note: Lumen measurements may be off by 10% with my DIY lumen tube.

Amutorch BT35 runtime graph

Amutorch BT35 first 10 minutes runtime graph

High quickly ramped up to 323 lumens, dropped to 165 lumens after 10 minutes, dropped to 150 lumens after 55 minutes, maintained 150 lumens until 2 hours and then turned off. A little over 2 hours is better than the 1 hour 20 minutes from Amutorch.

Low maintained around 100 lumens for 3 hours 30 minutes before flickering and turning off. The runtime is shorter than the 4 hours 30 minutes from Amutorch. Amutorch used an Amutorch 18650 3200mAh cell while I used a Samsung 30Q 18650 3000mAh cell. That might explain some of the runtime difference but it may not account for a whole hour.

Overall, the runtime and regulation is good.

Throw

I positioned the Amutorch BT35 20.14 metres away from a UNI-T UT383BT light meter and took lux measurements after 30 seconds for Low and High modes.

Two Samsung 30Q 18650 3000mAh cells were charged to 4.20V and used. One cell was used for Low and the other was used for High.

Mode Specs (cd) Specs (m) Candela measured (cd) Distance (m)
Low 162,247 805
High 470,000 1,370 451,454 1,343

Beamshots

I went to a local park and aimed the Amutorch BT35 at a tree 100 metres away while using High.

Beamshots were taken using a Sony RX100M2 using 1.3", f3.2, ISO 800, 5000K WB.

Amutorch BT35

Amutorch BT35 High beamshot

Weltool W4Pro

Weltool W4Pro High beamshot

Conclusion

The Amutorch BT35 is a lot of fun! I highly recommend it as an affordable entry level LEP torch.

I love that it produces a lovely white beam. I had the impression that all LEPs would produce an ugly yellow or green beam.

The beam distance and runtime were slightly lower than advertised but they are pretty close.

I had hoped that my pocket throwers would perform like this. The Amutorch BT35 is a great upgrade from a LED thrower with a TIR optic.

Pros:

  • Lovely white beam
  • Good regulation
  • Forward clicky tail switch
  • Pocket sized
  • Fits my hand perfectly

Cons:

  • Runtime for High was lower than advertised.

Product page

Promo code: TimMcAU
Promo code: TIMMC

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