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Fenix RC10 pre-production Review

6 Januar 2012
Fenix are shortly going to release their first ‘rechargeable’ light, the RC10. Intended as an always-ready light the RC10 is not primarily designed for the user to swap batteries, but instead to keep it topped up in its wall mounted charging cradle, ready to go when needed.

All comments in this review are limited to the pre-production sample I have. The final RC10 may differ slightly from this pre-production sample.

Initial Impressions:

The light itself is a somewhat typical single 18650 type of light. Clean lines and a simple shape with enough textured grip to be practical and give the RC10 a “Nothing fancy, just gets the job done” look.

The fit of the light into the cradle is precise and secure giving a good sense of quality.

What is in the box:

Being a Pre-production sample, there was no packaging or spares provided, so this section is not applicable here.

RC10 - as supplied with wall charger cradle and mains adaptor. The production release will include a car charger adaptor as well as the mains one, making the RC10 a possible choice for a vehicle mounted utility light.


The RC10 light itself


Taking a closer look and looking inside:

The RC10’s main difference to the rest of the Fenix line up is the in-light battery charging. Here the RC10 is shown fitted into the charging cradle, which based on the text direction on the light and cradle is mounted lens upward.


With the light removed you can see the charger contacts and the spring loaded retaining clips. The charging contact plate in the cradle is also spring loaded meaning it has some give. If the light is not quite fitted properly, the cradle contact plate will move instead of breaking or marking the light.


The power adaptor, either mains, or car adaptor to be included in the final release is connected to the cradle using a proprietary connector.


Looking at the top and bottom of the mains adaptor, apart from the Fenix logo, there is no specification information marked on this sample.



Turning the RC10 over reveals the charging contacts on the head of the light. The contact plate has two metal terminals (hex head bolts), and in the contact plate there are two differently sized slots that act as a key and prevent the polarity from being reversed if you managed to somehow fit it into the cradle upside-down (which is not possible anyway).


Looking directly at the Cree XP-G R5 LED


The RC10 is not designed to have the user constantly swapping out a used battery for a freshly charged one, so in normal use you would not take the tailcap off the RC10.

The threads are typical Fenix trapezoid fully anodised threads.


The battery contacts in the tailcap are unusual. The RC10 uses a proprietary battery the ARB-L1 (shown further down) which has both positive and negative contacts on each end, with the central part being the positive and the ring surrounding it, the negative. The tailcap and internal head contacts are the same with a central domed contact and a ring of four contacts surrounding this.


The ARB-L1 battery appears to be built on an 18650 cell, but with protection built in and unique set of contacts that are the same both ends. The battery can be inserted into the RC10 either way round.


The contacts are the same at each end of the battery and inside the red inner ring is positive and the outer ring is the negative terminal.


Modes and User Interface:

The RC10 has the main forward clicky tailcap switch for on/off/momentary operation, and on the side of the tailcap there is a circular button for changing modes.

There are four constant modes and a strobe.

Strobe can be accessed in two different ways. With the tailcap switch off, press and hold the mode switch for over 1s and the RC10 will enter strobe. This is maintained as long as the side switch is held in. Alternatively, with the tailcap switch on, press and hold the modes switch for 1s and the RC10 enters the strobe mode. Strobe is now maintained until the mode switch is pressed briefly, or the tailcap switch is turned off. Strobe is not memorised.

The constant modes are accessed either using the forward clicky switch. With the tailcap switch on (either momentarily or latched on) the last accessed constant output mode is activated. While on, the mode switch is used to cycle through Low-Med-High Turbo.

Batteries and output:

Supporting only the Fenix ARB-L1 proprietary battery, which so far is only used in the RC10, the only choice for spare batteries, if you wanted them, would be extra ARB-L1 batteries. The ARB-L1 has built in over-charge and discharge and thermal protection.

The RC10 is not really designed for the user to change batteries, as its intended use is as an always-ready rechargeable light. Much like you would leave a cordless phone in its charging cradle, you keep the RC10 topped up in its cradle to be, so don’t really need extra batteries. They will be available should you want a spare or two.

An early draft of the instruction manual states output levels of:
5 Lumens -142H
40 Lumens -26H 30M
140 Lumens -6H 10M
380 Lumens -1H 55M

With Strobe at 380lm

The modes are regulated and do not use PWM. When the battery can no longer provide maximum output, the high mode simply dims gradually. As there is no sudden cut off so you will not be left in the dark and have plenty of warning.


Using a calibrated integrating sphere the test sample gave 414lm fresh off the charger.

Fenix state “The RC10 has a low-voltage warning function. When voltage is checked, the flashlight enters the lower brightness level; if low voltage is checked in the Low brightness level, it will blink three times per second every five minutes. In this case, the battery should be charged or it will cause damage to the battery.”

In tests, so far I have not encountered this, as the output drops sufficiently that you want to recharge long before this happens.

Being power related, I will also mention some observations in this section regarding the charger. The output of the mains adaptor appears to be directly applied to the contacts on the RC10. Measuring the voltage at the connector of the mains charger while not connected to the cradle measured 4.22V. On connecting to the charging cradle, the voltage was measured as 4.22V at the cradle contacts. The cradle simply passes through the mains adaptor voltage.

The RC10 was fitted to the cradle and test wires inserted between the contacts to monitor the voltage. As the charging cycle neared completion, the mains adaptor light went green while the contact voltage measured 4.18V, however the voltage at the contacts continued to rise until it settled at 4.22V at which it is constantly maintained.

The battery was then removed and the resting voltage measured 4.22V and after 8 hours resting at 4.21V.

(results were verified using three different voltage meters)

I have queried this with Fenix who stated that their normal working parameters have a battery at full charge between 4.13V-4.23V, so this is within normal operating values and is of no concern. They also added that the battery is protected for over charging and over temperature so will protect itself.

This seems a little too high for a li-ion float-charge in my opinion, but is normal according to Fenix. It will be interesting to see the long term effect on the battery when kept at this voltage for an extended period.

In The Lab

In an attempt to quantify the actual beam profile I developed the following test. There are probably many flaws in my method, but it is simple and easy to carry out and seems to provide a good enough comparison.

The method used was to put the light on the edge of a table 1m from a wall, with a tape measure on the wall. The zero of the scale is placed in the centre of the hotspot and a lux meter is then positioned at points along the scale, with the measurements recorded. Beam shots are often taken with the light shining on a flat white wall, so this method is simply measuring the actual intensity across the beam on a flat surface, not the spherical light emission.

The results are then plotted on a graph.

For the best throw you want to see a sharp peak with less of the distracting spill. For the best flood light the trace should be pretty flat.

Here I have compared the RC10 to my reference Cree R2 profile. The RC10 has a strong hotspot and the profile of a light with lots of throw. The beam is apparently much like the TK15.


Taking this a little further, I calculated an approximate factor to apply to the lux measurements, as each measurement gets further from the centre of the beam, it corresponds to a larger area onto which the light is falling. It seems to me that this should also be taken into consideration, so I applied these area corrections and came up with this odd looking graph.

The key quantity here is the area under the graph line. This should correspond to the total light output.

The RC10 is a strong thrower, as shown by the peaks near the centre of the beam profile but still has some useful spill light.


The beam of the RC10 pre-production

As shown by the previous beam profile graphs, the RC10 has a very strong hotspot giving it plenty of throw and a long beam range.

The first beamshot is exposed to give an impression of the beam’s brightness to the naked eye.


This second photo has the exposure reduced to show the bright hotspot and how it compares to the spill area.


Using the RC10


The RC10’s simple shape is comfortable to hold, however, put it down and the complete lack of anti-roll design features means it won’t stay still and starts to roll about.

Solidly built, the RC10 feels like it could take plenty of rough handling and would survive well as a tradesman’s work light.

On Turbo, the RC10 gets quite hot after 15-20 minutes or so, but never so hot you can’t hold it. There is no noticeable increase in temperature using any of the lower modes.

The bright hotspot can be overpowering at closer ranges requiring you to hunt around with the hotspot to find what you are looking for. Outside this is not such an issue as at greater ranges, the hotspot gives you a strong search light which cuts well into the distance.

Of course, for use indoors the RC10 has plenty of output for bouncing off the ceiling for nice even illumination.


Use of a forward clicky and separate mode switch makes this a very immediate and easy to use light. There is a noticeable delay for all output levels. I would estimate the delay as about 0.2s from pushing the switch to the light coming on. This is merely an observation as it has no real bearing on general use.

The wall holder/charging cradle, holds the RC10 securely and the sprung retaining clips operate smoothly. The RC10 won’t come out if knocked, but is released easily enough when you want.

The RC10 is the type of light you may keep in the garage, utility room, basement or car/van/lorry where you want a light on hand, neatly mounted and fully charged.

In the RC10 you get a complete package; powerful light, built in li-ion battery pack, charger cradle and choice of mains or car chargers.

Once wall mounted, and if kept on charge, the result is a fit-and-forget, always ready to go, high performance, light. This makes it suitable for someone not familiar with the requirements of li-ion battery maintenance but who wants the output levels only li-ion gives in a light this size.


Test sample provided for review by The Photon Shop.

I’ll update post 2 of this thread once I have some more comments to add....


29 April 2011
der Ottostadt an der Elbe
Hey subwoofer,

another great review! Thanks! :thumbsup:

I like the RC10 and the charging mechanism. It's ideal for people not wanting to always take care of lithium-ion rechargeables with an extra charger, checking the voltage before and after charging it.
It could prove to be a good emergency light for the car. Leave it in the charger, always ready. I like that idea! :)

Keep in mind that you're only able to edit your posts within 24 hours after you've posted them. After that no editing is possible but for TLF Staff (Moderators/Admins).
So if you need to edit a post after 24 hours just send me a PN and I'll edit it for you! :thumbup: