Rovyvon E3 Review – A Keychain Light that’s Different


Pricing & Availability

Rovyvon sent me this light in exchange for an honest review. Here is the official product page and here is the Amazon page where you can see current pricing.

What comes in the box?

The box is a really cool little plastic bin thing, similar to what 18650 batteries come in, not a boring cardboard box. There’s a cardstock insert inside to hold the light in place. The following items are included in the box:

  • The light itself
  • Two different split rings for attaching to a keychain
  • User manual
  • Pocket clip (not attached to the light)
  • Notably absent is a charging cable, which is fine because you’ve already got half a dozen of those in a drawer somewhere.

Design & Construction

The design is one of the most interesting things about E3, because it’s not a cylinder like most flashlights. It’s a flat rectangle.

Build quality is pretty nice. It feels well machined & well finished. The latch feels a bit flimsy though.

Size & Measurements

Emisar D4V2 | Olight i3E | Rovyvon E3 | Wurkkos TS10 | Lumintop FW3A

Rovyvon advertises E3 as a keychain light. While it can fit on a keychain, I think it’s a little bit big for that. This strikes me more as a watch pocket light.

MeasurementMeasured (mm)
Length (Maximum)66.3
Length (Mode)61.8
Width (Maximum)28.6
Width (Mode)27.5
Thickness (Maximum)14.7
Thickness (Mode)13.5
Switch Diameter6
Switch Proudness-0.3
Battery Tube Diameter (internal) 10.6
Ride Height (sticking out of pocket, not including keyring)9.2
Pocket Clip Space (for pants material)3
Pocket Clip Space (at mouth)2.5
Pocket Clip Width7.0
Pocket Clip Thickness0.7

Weight without AAA battery: 35g
Weight with Amazonbasics NiMH AAA battery: 46g

User Interface

This is not the typical e-switch UI. E3 is designed for use on a keychain so this UI was designed around that use case to prevent the light turning on by accident.

The actions are # of presses followed by a hold (H) or a release (C). So, “1C” is one click and release. “2H” is two clicks but you hold down the last one.

Off1CMoonlight (not memorized)
Off1HHigh (momentary)
Off2COn (mode memory)
Any (except Moonlight)3CStrobe
On (normal modes)1CCycle mode (Low-Med-High, memorized)
On (normal modes)1HOff
Moonlight3CToggle between built in battery and AAA battery
Lockout1CBlinks battery indicator LED

What I like:

  • Moonlight has its own dedicates shortcut and isn’t memorized nor included in the normal mode rotation.
  • Momentary high is great and it’s what I used most of the time
  • Strobe is hidden outside the main mode rotation
  • It has electronic lockout and it uses multiple clicks instead of just a simple hold. That’s really important on a light with no way to remove the battery.

What I don’t like:

  • This UI varies a lot from most e-switch UI’s and that makes it really take some getting used to. Most of the changes make sense for a keychain light though.
  • No way to go from moonlight to low
  • Turning it off requires different actions depending on what mode you’re in, and that’s confusing. I think using 1C for off across all modes would be much better.
  • Switching between the two batteries is a little fiddly. I wish there were a mechanical switch on the side of the light to toggle between them.

Emitter & Beam

E3 uses two Luminus SST20 emitters. Mine are 6500K, but you can also get 4000K, or one 6500K and one 4000K. I recommend getting all 4000K.

The beam is pretty nice. It’s a wide hotspot with relatively well defined edges. There are no real artifacts to speak of.

Rovyvon E3 | Wurkkos TS10 (E21A 3500K, ~600lm)
Rovyvon E3 | Olight i3E

In the beamshots above, the trees where I’m aiming the hotspot are 175M away. In the beamshots below, the park bench where I’m aiming the hotspot is 42M away.

Rovyvon E3 | Wurkkos TS10 (E21A 3500K, ~600lm)
Rovyvon E3 | Olight i3E
Rovyvon E3 | Acebeam X75 (just for fun)

Mode Chart

Disclaimer: All of my measurements are taken at turn-on. Lumen measurements were taken on a Texas Ace 3.5″ Lumen Tube. A candela measurement was taken at 10 meters with an Opple Light Master III on the highest brightness, and other candela figures were calculated relative to that. CRI, CCT, & DUV data was taken for each mode from a few feet away at the center of the hotspot with the Opple Light Master and Waveform DUV Calculator. Runtime tests were performed with the Ceilingbounce app on my smartphone. All of these tests were performed with a fully charged built in battery (and a fully charged Amazonbasics NiMH AAA as a backup) unless otherwise specified. I cannot measure moonlight directly, so moonlight readings are calculated based on the brightness relative to the next-lowest mode. None of this is professional equipment, so take all of these measurements with a grain of salt.

Above are the official specs, followed by my own measurements below.

LevelLumensCandelaThrow (Meters)
I didn’t bother to measure CTI, Color temp, or DUV on this light because anyone who cares about those things should get the 4000K version. I also only tested these modes with the build in battery, since the AAA is just for emergencies.

Mode Spacing: is good. There are no weirdly small or large jumps.

Moonlight is substantially dimmer than advertised and substantially dimmer than most other flashlights. That’s a very nice surprise.


Performance: is fine. There’s a timed stepdown from High mode at the 2 minute mark, which is a nice long time. You can see in the graph where the light switches from the built in LiPo battery to the AAA, because output drops suddenly to about 60 lumens on High and Medium modes. Total runtime on low mode is nearly 21 hours.

Thermal regulation: There’s a timed stepdown on High mode at the 2 minute mark. I didn’t observe any active thermal regulation, but that’s really not important on a keychain light.

LVP: When the LiPo is empty, the light will switch to AAA. Based on the graphs it looks like there is some kind of LVP for the AAA, but I don’t know what the voltage cutoff is.

Driver & Regulation

To run on AAA’s this must have a boost drive circuit, but I’m not sure whether that’s also used for the built in battery or not. Based on the runtime test it seems to be reasonably well regulated. I did not perform separate regulation testing because the primary battery is built in.

PWM: No PWM is visible to my eyes or camera, nor audible to my ears.

Parasitic Drain: could not be measured off the built in battery. I measured 20 microamps of parasitic drain from the AAA, which theoretically should take about 4 years to drain an NiMH cell.


E3 has an metal, electronic, side switch surrounded by a small retaining ring. It’s very easy to find in the dark because it’s proud, but the ring protects it from accidental activation. It’s quiet (for an e-switch) and is tactile enough to feel when it clicks. It’s a good switch and it’s in a good location. I like it.

Carry & Ergonomics

Ergonomics aren’t great because it’s a very small light, but it’s fine in the hand. There aren’t any hotspots and it doesn’t try and jump out of your hand.

Two carry methods are included: pocket clip and a keychain loop. I don’t like having a light on my keychain so I used the pocket clip briefly and it works well enough. It’s reversible so you can clip the light to a hat if you want. It also carries nicely in a watch pocket with no clip.

Tailstand: is possible if you set it on the lanyard loop thing just right. It’s not super stable but it should stay up if you don’t bump whatever it’s sitting on.

Batteries & Charging

The battery situation is the second of the two big selling points (the first being the rectangular shape). There’s a built in lipo rechargeable battery and a slot for a AAA cell. Alkaline or NiMH will work, but no 10440 support. This setup allows you to use the rechargeable lipo for day-to-day use but also have backup power & instant-rechargeability with AAA’s. The “head” hinges open to reveal the AAA battery compartment and it’s held shut by a little clasp that feels a little flimsy and unsophisticated.

The gasket that seals the battery compartment is glow in the dark! Neat!

I don’t love this battery setup. I dislike built-in batteries because they wear out and then your light is useless, so adding the AAA slot is nice. But, why not just get rid of the built-in battery entirely and add a second AAA slot and support for 10440 cells? You may be able to extend the service life of E3 with AAA’s but you’ll lose the recharging functionality and a lot of output.

The argument could be made that that’s dangerous because someone might use a 10440 and a AAA at the same time. Or, they might try and recharge alkaline AAA’s. That’s true, but I imagine circuitry could be added to minimize that risk. Ultimately this feels like a half-baked battery solution to me, like Rovyvon wanted to “listen” to user’s concerns about built in batteries but keep using them anyway so that when the built in battery wears out, the user will go buy another new Rovyvon flashlight.

Charging is facilitated by a USB-C port on the side of the light opposite the switch and near the tail. The port cover is pretty flimsy and I don’t like it very much. If I were to carry this light daily I might just remove the port cover. C-to-C charging works just fine and charging takes about an hour. There is no option to recharge a AAA battery inside the light. It does not work as a powerbank either (not that I expect it to or think it should, but someone is going to ask).

There’s a blue charging indicator LED next to the charging port to indicate charging status and it’s not great. It slowly breathes blue while charging and turns constant blue when fully charged. That means that you can’t tell if it’s charged or not just by glancing at it. You have to look at it for a couple of seconds to see if the indicator is breathing or if it’s constant on. A classic two-color indicator where red means charging and green means fully charged would be much better and easier to use.


Here are some lights in the same class and how they compare.

Rovyvon Aurora Series (3rd gen): Same UI, switch location, charging, etc. Half the size but no AAA backup support.

Basic 1xAAA twisties: One or two modes, twist the head for on/off, no charging, half the size, typically less than $10, use common AAA’s, typically not as bright

This section is not comprehensive. If I didn’t include a particular light here, it doesn’t mean it’s bad or doesn’t deserve to be here. I simply cannot list every possible competitor.


Rovyvon tends to make lights that push the boundaries and innovate. Sometimes that results in hugely successful and excellent models (like their Aurora series). Sometimes it results in obscure lights for niche markets. This is somewhere in the middle.

If you really like the flat brick form factor or the unique battery setup, this is one of very few lights that offer those things so it may be a good fit for you.

For me, the UI is weird and confusing. They made it that way to keep it from turning on while on your keychain, but it’s too big for keychain use for me. If I’m not carrying it on my keychain, I want something larger, more capable, and with a better user interface. I also don’t find the AAA backup option compelling. If I were looking for a keychain light I would get a small tube light like one of Rovyvon’s latest Auroras with USB-C or go cheap and get one of the various 1xAAA twisty lights.

Thanks to Rovyvon for sending me this light for review!

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