4Sevens Preon ReVO


The ReVO is the second single AAA light (The first was called Preon) from 4Sevens. The light has keeps nearly the same modes as the Preon, i.e. 3 brightness settings and 3 hidden flashing settings, with the same twisting user interface where the light always turn on in low mode. A fast off/on sequences is used to change to next mode, to get to the flashing modes 7 off/on must be performed at power on. The standard version of the light is made of aluminum with hard-anodized (Type 3) finish, but there were also made a series of light in stainless steel.

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The light is delivered in a textured cardboard box with a window. The backside of the box is a sticker with specifications (Same sticker is used for SS and aluminum, i.e. it says aluminum even for the SS version).


The contents of the box are the light, a battery, spare o-ring, a split ring and the manual.

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The light uses a XP-E led placed in the center of a small OP (Orange Peel) reflector.


The head has some groves to improve grip when twisting the light.


The actual light engine is mounted in a brass insert that also has the threads and o-ring. Using brass for threads gives a very good quality threads.


The battery connection in the head is surrounded by a black soft ring, this ring will reduce battery rattle and work as a mechanical polarity protection. This light does not use the standard ring on the circuit board for power connection and on/off, it looks like the switching is done by breaking the battery connection, both at the top and bottom.


The inside of the battery tube, it also has a soft ring. There is no spring, but the connection has some flexibility.


The outside of the battery tube has ample knurling and gives a good grip on the light.


The backend of the light is made for use on a key chain (Use the supplied split ring between the key chain and the light). On plain surfaces it is just about possible to tail stand the light.


This is the parts I could disassemble the light into without using tools.


Here I have illustrated the mode sequence, the light always start at low and when high is reached it will go back to low, only exception is when the light is turned off/on until strobe/SOS/Beacon is reached immediately after power on.

I like this light, it is just about the perfect key chain light, especially the stainless steel version.

Technical specification and measurements


This light is designed for 1.5 volt AAA batteries (Alkaline, NiMH, Lithium).

Measured size and weight:
Length: 72.4 mm
Diameter: 12.8 mm
Weight: Aluminium: 23.2 gram with eneloop, Stainless Steel: 35.2 gram with eneloop

The light uses a Cree XP-E R2 led.


In the above table I have used 800mAh eneloop batteries for measuring and estimating the runtime. The estimated lumen are based on the specified 82 lumen and then scaled according to measured brightness. For this light I believe that specified, measured and estimated values do match very well.
The light has two high levels, the full power level will only run for 3 minutes, then the light will reduce brightness.


The voltage scan show that the light is stabilized down to around 0.8 volt, but this stabilization has a down side, the light can use up to 2 ampere from the battery!


The runtime clearly shows the step down after 3 minutes in the high brightness setting. It also shows that alkaline has a very short runtime at high and not enough power to keep the brightness stabilized.


The light uses current control for the brightness settings, i.e. no pwm. But the regulation has some high frequency noise in it at around 66 kHz. This noise is invisible to the eyes. The above trace is from high.


The strobe is 8.9 Hz with 33% duty cycle using the high brightness setting. The regulation can also be seen here.


The SOS uses a 0.36 second pulse as dot and it takes 12.8 second for a full sos, then a 3.3 second pause before the next. The SOS uses high brightness and does not turn completely off between pulses, but stays at low.


The beacon is a short flash (0.23 second) at medium brightness with 11.4 second between. The light does not turn off between flashes, but stays at low.
When selecting beacon, the light will flash 5 dimming pulses as confirmation (Second graph).

Comparison to other Flashlights

Ray S20 NiMH, Ray S20 LiIon, 4Sevens Preon ReVO
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4Sevens Preon, Fenix LD01, ITP A3 update
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For the full comparison to other lights with graphs and beamshots see here.