Imalent RT90

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Imalent RT90 specifications

Brand/model	Imalent RT90
LED	Luminus SBT90.2
Lumens	4,800 lm
Beam intensity	427,980 cd / 1308 meters
Battery config.	battery pack: 4*18500
Material	Aluminum
Modes	4+Turbo
Blinkies	Strobe
Reflector	Smooth
Waterproof	IPX8
Review date	January 2021

When it comes to high-power flashlights, you will inevitably come across Imalent. Imalent is always trying to push the boundaries. That’s how they produced the 100,000-lumen Imalent MS18 we reviewed, but also the Imalent MS03, a single-battery flashlight with 13,000 lumens. But this time, they wanted something a little more conservative, but still ‘special’.

This time, they produced a short powerful flashlight featuring the Luminus SBT90.2 LED. This LED is able to push about 5000-6000 lumens at max, but instead of using the commonly used 18650 batteries, they decided to use 18500 batteries instead. This results in a pretty short and compact thrower. I’m not a fan of single-cell powered flashlights with the Luminus SBT90.2, but I hope I won’t be disappointed with the 4*18500 SBT90.2.

Package quality.

Within the package you get the following:

• The flashlight Imalent RT90
• Charging cable
• O-rings
• Holster

The user manual was missing from my package. According to their website, the box should have included a manual. They sent me the manual by email.

Before you use the flashlight, make sure you remove the washer between the driver spring and the battery pack. Just unscrew the body, and remove the washer.

The flashlight contains of 2 main parts, the head, and the body. The head of the flashlight has no knurling, and the knurling on the body is not very rough. This results in a slippery flashlight.

The switch is located in a relative convenient location if you have light. When you don’t have enough, or any light, the switch is hard to find. Many flashlights include an indicator led around the switch, but the RT90 doesn’t.

However, it does have 2 small LED indicators on 2 sides of the flashlight, but they are only useful to see the battery status.

1 thing I thought was missing is a tripod socket. Throwers in this category usually have a tripod attachment so you don’t have to hold it in your hand. There is also no lanyard attachment point on this flashlight, so you either have to carry it in your pocket or use the included holster. So 1 benefit of having almost no knurling, is that it won’t damage your pockets.

Tailstanding? no problem.

One thing I hope they will improve is the O-ring between the body and the head. First of all, it’s rather difficult to tighten the head and body, and secondly, the o-ring is probably a bit too thick and squeezes out at some points. I would suggest not unscrewing the body too often.

Since there are only 2 parts, I can’t tell much about the inner construction. The batteries are not replaceable unless you take the battery pack apart. I tried it, and I failed. Probably needed to use more force. I could remove the brass ring, but couldn’t get the contact board out.

The holster looks fine, with a velcro strap and a loop for a belt to pull through. And on the top is a plastic attachment ring.

In the digital manual I received, I couldn’t find anything about the warranty. For details on the warranty, have a look here: https://www.imalent.com/service/

One of the current popular LEDs is the Luminus SBT90.2. This is a high-power LED that can reach up to 5-6000 lumens. But only if you drive it hard with high-discharge batteries.

The SBT90.2 is not only a high power LED, it also has a flat silicon cover instead of a silicon dome. This means that the LED is useful for long-range applications. The LED is therefore considered a useful, high-power ‘thrower’ LED.

The LED sits deep and well-centered, in a smooth reflector. The glass lens has a purple hue, which indicates it probably uses some AR coating (anti-reflective). The beam is a little greenish in low mode that is not visible when you come to Med 2 or higher.

• Length: 127.8 mm / 5”
• Head diameter:  64.2 mm / 2.53”
• Body diameter: 51 mm / 2”

Weight: 

• Weight: 448.5 g / 15.82 oz

High Power Thrower Flashlights

Size compared to other high power flashlights.

From left to right: Acebeam X45 II, Fenix LR35R, BLF Q8, Lumintop GT3, Imalent RT90, Acebeam X80-GT, Fireflies ROT66 II.

Unfortunately, I didn’t receive a manual with my flashlight. But after asking they were kind enough to send me a digital copy of the manual by email.

Available modes:

• Low, Medium 1, Medium 2, High, Turbo
• Strobe

From OFF:

• Single-click: to last used mode, (mode memory)
• Double click: Turbo
• Triple-click: Moon
• 4 clicks: Lockout mode
• Press and hold >3sec: Turn off/on both battery indicator LEDs on the side

From ON:

• Half-press: Cycle through the menu from Low to High
• Single-click:  (to last used mode, mode memory)
• Double click:
• Triple-click:
• Press and hold:

Shortcuts:

• To Turbo: Double click from either off or on
• To Low: Even if it memorized Mid1 or High, with a triple-click from Off you will always turn on in Low.
• To Strobe: 2* double click from Off or 1* double-click from on

Mode memory:

• Yes, by default.

Blinky modes menu:

• There is only a strobe mode. 2 times a double click.

Low battery warning:

• The side indicator LEDs will turn red. And the flashlight will blink according to

Lock-out mode:

• 4 clicks from when the flashlight is off.

PWM:

• Not visible by eye

Many Imalent flashlights have proprietary charging systems, and the RT90 does too. Charging goes at a charging current of up to 2.3A. One word of warning, please always use a USB tester that shows the charge current. The 2 copper charger contact points are quite sensitive, and if you don’t attach them correctly, the charge current can be very low. I’ve noticed mine charging at 0.4A for a while, and after re-attaching the cable, it started charging at a much higher current again. It’s impossible to accidentally reverse the charger cable because the contacts won’t be able to make contact.

Also make sure you clean them regularly with some rubbing alcohol.

Inside the battery pack are 18500 cells, according to Imalent. These are roughly 1.5cm shorter than 18650 batteries, but only have half of their capacity. So adding 1.5 centimeters would have resulted in a much longer output. I tried to open the battery pack, but could only remove the outer ring. The contact board moved a little, but I couldn’t get it out. I have a feeling there is something behind the black plastic ring.

During charge 2 red LED indicators are lit. They are on 2 sides of the body, 90 degrees on each side of the switch.

Some comments:

When the battery runs low, and you try to activate Turbo a few times, the light starts to flicker (like it says in the manual) and turns off. I wished they could just reduce the output to low instead of turning off. Some people may start complaining about this. To me, it happened when I went from Turbo to Strobe, and then double click again to go back to Turbo.. At that point it started to flicker and switch off.

Lumen measurements:

All output numbers are relative for my home-made Integrating Sphere. It is set up with an Extech SDL400 Lux Meter for measurements including a Kenko PRO1D ND-16 filter. The base measurement is done with a Convoy S2+ that has been tested at 255 lumens.

My measurements at the start and after 30 seconds. I usually start with the highest output. Then charge the battery/flashlight, and then do high… I typically don’t charge the battery between measuring the lowest modes because the output won’t drop much anyway. Amps were measured with a Fluke 77III and original probes. Turbo mode could only be checked shortly, or I would blow a fuse and got about 18.9A.

Mode	Amps	Specifications	30 sec	start
Low	0.02A	10	14.04	12.92
Middle 1	0.52A	350	479	481
Middle 2	2.2A	1350	1292	1320
High	9A	2800	2803	3095
Turbo	18.9A	4800	2893	4668

Do you notice that Low mode increases brightness slightly in the first 30 seconds. I couldn’t get to 4800 lumens, but at start, it was pretty close at 4668.

Runtime:

The runtime test was done with the 50cm integrating sphere, including the Kenko Pro1D ND-16 filter and Extech SDL400 data logging Lux Meter.

Please have a look at the following graphs

From the runtime graph, we can see that Turbo drops in about 1 minute and 10 seconds to 1250 lumens. And the sustained output roughly between 1200 and 1250 minutes for 30 minutes and then slowly decreases to about 960 lumens at 58 minutes. At that point, it starts to step down to about 280 lumens at which point it is actually the end of the runtime, according to the ANSI FL1 standards. You still have about 18 more minutes before it shuts off completely.

High starts at roughly 3100 lumens and quickly drops to about 1250 lumens, just like Turbo. And it’s interesting that High has almost the same runtime graph as Turbo. I hoped it would have a higher sustained output, but this is still not too bad at roughly 1250 lumens. Still, I don’t personally like this too much, for this size of light.

Med2 also has roughly the same runtime graph as High and Turbo. I think Imalent should have only used either High or Mid2 instead of both because they literally have the same runtime graph after the first drop. I wished they had Mid 2 at 1000 lumen continuous output for 2-3 hours instead.

Mid1 has a pretty stable output for 4 hours and 30 minutes at which points it starts to decrease output slowly till 4 hours and 56 minutes when the light shuts off.

I didn’t measure Low, but according to the manual it is supposed to run for 90 hours, or 4 days and a bit.

Throw Measurement

Measurements were taken both indoors and outdoors with a professional Hagner E4-X Lux Meter. The problem with measuring the SBT90.2 manually is that it starts dropping really quickly. And when you have to walk 20 meters (for measuring), it becomes even more difficult to get the best reading at 30 seconds. So please take the following measurements with a grain of salt. I had to redo the testing indoors at 5 meters to read the Lux meter at the start and 30 seconds without walking 20 meters.

Measurement at 5 meters	Candela	Meters	Yards
@ start	336,750 cd	1161	1269.25
@ 30 seconds	182,000 cd	853	933.10

Specs say it has a beam intensity of 427,980 which I couldn’t reach, not even at start from 5 meters. According to ANSI FL1 standards, candela should be measured at 30 seconds, and that is not going to be 427 kcd.

For the following beamshots with the tower, I used a Canon EOS 5D Mk2 and a 100mm lens. manual settings: ISO1600, .5sec , F4, 5000K. The tower is about 450 meters / 492 yards away. It gives you an idea of the different types of beams.

The second set of shots (with the shed), are done with the same camera, but with a 50mm lens. manual settings: ISO1600, 1/4sec, F4, 5000K. The shed is about 65 meters / 71 yards away, and the fence about 200 meters.

Disclaimer: This flashlight was sent to me for review at no cost by Imalent. I have not been paid to review, nor have I been holding back on problems or defects.