Nitecore SRT 7 UI problem with RCR123 - is this normal?

I've owned a Nitecore SRT7 for a couple of days now. I use it with two Tenergy 3.0v Li-ion RCR123. Most of the modes work as expected, but I am having the following problem:

When the light is clicked on, going clockwise on the ring selector through the modes, all is well until Turbo / Max. When trying to go back (counter clockwise), the light turns off. Nothing short of an off-then-on click of the rear button can make it produce light again. None of the modes work without this reset. Sometimes the light also turns off the same way somewhere between 90% brightness on the continuous white mode and Turbo.

At first I thought the light was defective. However, since the batteries were not freshly charged, I ran them down a bit and charged them. With the fresh set, the light worked fine going forward and back through all modes. A few times. Then the same issue appeared. The light has not spent even half a minute in Turbo in total. This is super annoying because I was hoping to keep it on in standby mode and just select modes as the situation requires, but with this unpredictable off, I can't do it. It also prevents me from selecting strobe without using the rear clicky. BTW, the red standby / battery charge indicator does not blink with my RCR123s except in standby mode, so it did not give me any low battery indication. I have no way to check the actual voltage of my batteries, but they do work just fine in my Sunwayman and Fenix lights. If the SRT7 is unable to support Turbo on my batteries, I would expect a slightly more civilized behavior, perhaps lower output, blinking, or anything but a hard reset.

Is this normal or is my light defective?

I don't own this light and can't comment much but I am figuring it has to do with your batteries. Why don't you try running it off 18650 instead? It seems like your Tenergy batteries are not able to provide ample amount of power to support the SRT 7.

The SRT7 Manual says RCR123 with a Nominal Voltage of 3.7V is Compatible. The Max setting of the SRT7 is very demanding on batteries. I'm thinking that you are probably on edge with the 3.0V RCR123s. I'm not an expert, but that's the only thing I could think of off hand.


UPDATE: I found a pair of Tenergy 3.0v batts I happen to have lying around. I got the same results described by the OP. Going back to my 18650 shows normal operation. Must be the lower voltage of the tenergy batts.

All things equal, an RCR123 has much lower capacity than any 18650. Compare the 550 mAh actual capacity of an RCR123 to the 3100 mAh actual capacity of an 18650. Just from that, an 18650 can deliver 5x more current. Even with the 2xTenergy having 2x the voltage, it can only deliver (1/5 current) x (2x voltage) 2/5ths the power a single 18650 can.

Thank you for looking into it! I currently don't have any 18650. I guess I will have to commit to getting some and a charger, or use lights that don't require 18650 (can work reliably on RCR123).

Get some decent 3400 mah protected 18650 batteries and you will never want to go back to running two RCR in your light. Trust us. It has been worthwhile going that route.

pjandyho said:

Get some decent 3400 mah protected 18650 batteries and you will never want to go back to running two RCR in your light. Trust us. It has been worthwhile going that route.

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I agree. I remember starting with RCR123s, once I made the move to 18650s, I never looked back. That's why my RCR123s were just lying around. I just don't use them anymore, but I keep them around as backups.

After reading this thread,i decided to test running my SRT7 on RCR123a batteries. The ones i have is AW RCR123a 3,7V Protected 750 mAh Batteries. I could run the SRT7 at highest mode turning the ring down to low and up again without problems.I belive that the issues you experienced is because of your RCR123a batteries with it´s 3,0 V has to low voltage.

However something else happended that i found strange. I decided to test the SRT7 runtime putting it at highest mode with the AV RCR123a batteries and it ran for 31 minutes without any flickering or the battery warning indicator start to flash,but suddenly it stoped! I thought first that the light was damaged,but when inserting other batteries it worked again.Has anyone experienced this?

NorthernStar said:

After reading this thread,i decided to test running my SRT7 on RCR123a batteries. The ones i have is AW RCR123a 3,7V Protected 750 mAh Batteries. I could run the SRT7 at highest mode turning the ring down to low and up again without problems.I belive that the issues you experienced is because of your RCR123a batteries with it´s 3,0 V has to low voltage.

However something else happended that i found strange. I decided to test the SRT7 runtime putting it at highest mode with the AV RCR123a batteries and it ran for 31 minutes without any flickering or the battery warning indicator start to flash,but suddenly it stoped! I thought first that the light was damaged,but when inserting other batteries it worked again.Has anyone experienced this?

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If you use protected Li-ion batteries then you must understand that it is the protection circuitry of the batteries that is cutting in to shut down the batteries so as to prevent an over discharge of the batteries, and has nothing at all to do with the SRT7 or any other lights. Although it will leave you in darkness all of a sudden, I consider this a very good safety feature so that the user would not unknowingly run their batteries down and damage it.