Faulty Nitecore SRT-7?

dsherlock

Newly Enlightened
Joined
Feb 27, 2008
Messages
3
Wonder if anyone can offer some advice please.


This week I purchased a new Nitecore SRT7, along with an EagleTac 3400mah 18650 battery.


I charged up the battery using my Pila charger (which I use for my other 18650 batteries so I know it works) and went to use the new light. Immediately after switching on, the red status led flashed every 2 seconds, which according to the instructions means the battery is <50%. After 2/3 minutes, the light drops to a very low output and the red led flashes very quickly, indicating the battery is almost depleted. I reset the battery and charged again all day, but it did the same thing.


I then tried 2 brand new nitecore cr123a's in the torch, again, as soon as the torch is switched on, the red led start blinking every 2 seconds. This time the torch lasted 15 mins before the red status led started blinking rapidly.


I'm not sure if there is therefore a problem with the torch? If the slow blinking led does show a low battery when the torch is switched on then it looks to be a problem with the torch as it does it for both the new 18650 and cr123s (although it's worse with the 18650)


Anyone else have this torch and experienced this issue? I've been asked to send the torch back for testing, but wanted to check if anyone had experience of this before doing so.


Thanks in advance
 

Patriot

Flashaholic
Joined
Feb 13, 2007
Messages
11,254
Location
Arizona
I've seen the flashing light come on within 20 minutes or so but that was with a 2300mah older nitecore cell. If it's happening with a 3400mah and cr123's, I would send it back for replacement. Just a head's up, there are two other threads on the SRT Series and SRT7 already. :)
 

LedTed

Enlightened
Joined
Mar 7, 2010
Messages
740
Location
Britannia
I had a like scenario tonight with a freshly charged 2500mAh TrustFire 18650. I wondered if my new NiteCore SRT7 had a problem.
 

aau007

Enlightened
Joined
Sep 12, 2010
Messages
448
I suspect that the blinking light goes by the voltage of the battery under load. One way to tell if there is a problem with battery or light is to tap a Watt Meter thru it. It will then tell you the voltage and current draw at the same time and whether the blinking light operates accordingly. If I have to guess, I think the <50% blinks probably happens when voltage drops below 3.5/3.6 volt and that fast blinks at 3.0/3.2 volt.

If you don't have a Watt Meter, try a fresh battery and set the brightness half way to see if the blinking comes a lot later.
 

vladax

Newly Enlightened
Joined
May 4, 2013
Messages
8
I have the same issue. I'm using new Panasonic NCR18650B Protected, 3400 mAh battery. Fully charged with Jetbeam i4 PRO charger to 4.2 V. When inserted to the SRT7 the red light on the side starts blinking immediately.

From the manual:
When the SRT7 is switched on standby mode, it will consume small amounts of power to maintain the settings in the MCU (micro control unit) but appear to be turned off. The power indicator on the light head will blink once every two seconds to indicate the SRT7 is in standby mode and to act as a locator.

How I read it:
The blinking red means: I'm in the standby mode.

Btw. what settings are in the MCU? This light has no memory feature AFAIK.

But next from the manual:
When the light switched on, the power indicator will blink once every two seconds when power levels reach 50%.

How I read it:
The blinking red means: You have 50% of battery power remaining. This is not true for sure.

Slow blinking means standby mode, fast blinking means low battery.
 
Last edited:

Bigmac_79

Flashlight Enthusiast
Joined
Jun 3, 2011
Messages
1,511
Location
Kansas
Does this happen on the highest output level, or every output level?

I would say charge up your battery, measure it's voltage, then put it in the light and turn on the light. When the red light starts blinking, take it out and measure the voltage (even if the red light blinks immediately). Then, pop it back in and turn the light on until the output drops to very low and the red light blinks quickly, then take the battery out and measure it's voltage again. Let us know what happens. Also, immediately after you take the battery out each time, take notice of it's temperature and see if it's abnormally warm or even hot.

My guess is either there's some sort of short that's actually discharging the battery very quickly, or the voltage sensor in the light is off. Doing this should tell you which of those two is more likely.
 

CarpentryHero

Flashlight Enthusiast
Joined
Jul 4, 2010
Messages
3,096
Location
Edmonton
Other Nitecore lights have a beacon mode when there not locked out. The P25 has a beacon mode when in standbye or on too I think.
Could the slow flash just be a beacon to find the light?
 

aau007

Enlightened
Joined
Sep 12, 2010
Messages
448
I put a crappy 18650 cell, salvaged from a 4 years old laptop pack in the srt7. Fully charged I think I have about 1800mah max.

Ring at off position and tail switch off, no blink.
Ring at off and tail switch on, blinks once every 2 sec.
Ring at max brightness initially, no blink.
Ring at max after a few minutes, blinks once every 2 sec.
Turn brightness down and blinking goes away.
Turn brightness back to max and blinking comes back shortly.
Then it will blink every 2 sec. until the battery is low and fast blinking comes.
When fast blinking, the light is still visually a lot brighter than my 220 lumens Jetbeam.
Don't know when the light shuts down cause I never ran it to that point.

Keep in mind the battery is supposed to be pretty crappy after 4 years and is not a high drain battery to begin with.
 

CarpentryHero

Flashlight Enthusiast
Joined
Jul 4, 2010
Messages
3,096
Location
Edmonton
I put a crappy 18650 cell, salvaged from a 4 years old laptop pack in the srt7. Fully charged I think I have about 1800mah max.

Ring at off position and tail switch off, no blink.
Ring at off and tail switch on, blinks once every 2 sec.
Ring at max brightness initially, no blink.
Ring at max after a few minutes, blinks once every 2 sec.
Turn brightness down and blinking goes away.
Turn brightness back to max and blinking comes back shortly.
Then it will blink every 2 sec. until the battery is low and fast blinking comes.
When fast blinking, the light is still visually a lot brighter than my 220 lumens Jetbeam.
Don't know when the light shuts down cause I never ran it to that point.

Keep in mind the battery is supposed to be pretty crappy after 4 years and is not a high drain battery to begin with.

That sounds pretty good for an old cell. In my P25 if I put in my cheap cells (trustfire red,gold and white) the rapid flash is immediate on turbo.
 

candle lamp

Flashlight Enthusiast
Joined
Jun 16, 2010
Messages
1,572
Location
South Korea
I've tested with 2xPanasonic CR123A cells which were used for runtime test on max. output for other light before, voltage at present is about 2.85V for each cell.

1) Ring at standby mode and tail switch off, no blink.
2) Ring at standby mode and tail switch on, blinks once every 2 sec. (Note that the red status led blinks every 2 seconds at standby mode.)
3) Ring at max. output or med. output, blinks fastly.
4) Turn output down to min. and blinking goes away.
5) Turn output back to max. or med. and blinking comes back shortly.

I used 1xVicLite 18650(2600mAh) & 2xPanasonic CR123A's for testing SRT7 runtime on Max. output & 70% of max. output.
But I just remember 2) & 3) of the aboves in my runtime test. Hope you will fix it.​
 

vladax

Newly Enlightened
Joined
May 4, 2013
Messages
8
In my case the red led blinks all the time the power switch is on regardless the mode selected.

Sorry, it's not true. The led blinks only when the ring is in the standby mode.
 
Last edited:

LedTed

Enlightened
Joined
Mar 7, 2010
Messages
740
Location
Britannia
It looks like I pulled the idiot move of reinstalling the same battery I was trying to replace.
I tested the light on a known fully charged battery and I got an hour ten before the rapid flash.
 

aau007

Enlightened
Joined
Sep 12, 2010
Messages
448
In my case the red led blinks all the time the power switch is on regardless the mode selected.

Do the following trouble shooting steps and tell what you get.
1. Charge your battery to full and use a DMM to measure the voltage and make sure it is at least 4.1v off the charger.
2. Turn and leave ring to low mode.
3. Insert battery.
4. If light comes on, click tail switch to turn off. If light does not come on, that means tail switch at off position and go to next step.
5. Turn ring to standby position.
6. With step 4, we have made sure the tail switch is at off so the side should NOT be blinking (make sure).
7. Now click the tailswitch but leave ring at standby. In a couple of seconds, you should see side light starting to blink every 2 seconds or so.
8. Click the tail switch to off and make sure side light stops blinking.
9. Repeat 7 and 8 several times to verify this function works correctly, which I see no reason why it wouldn't.
10. Click the tailswitch to on, leave ring at standby and make sure side light blinks every 2 sec.
11. This is the important step. Slowly turn the ring to turn up the brightness to the point when you can JUST see the LED lighting up. Your side red light should stop blinking. If it continues to blink, take the battery out and measure the voltage to see if still over 4.0v. If it does, problem likely in the light.
12. If no blinking, continue to increase the brightness until max and observe when side light starts blinking every 2 sec.
13. Back off the brightness until the side led blinking goes away.
14. When the blinking comes back, keep backing of the brightness until the blinking goes away. Do that until the are pretty much at min. brightness.
15. Take the battery out and measure the battery voltage to see if your battery is at 3.7v or so.
16. If you get to this step and everything checks out, it is possibly the battery. Try a high drain capable battery like an IMR kind.

The key part to this test is whether the side led blinking operates normally. My tests have indicated that the blinking of the LED is determined by a combination of voltage and current. When I tapped a watt meter on it, the side light will start blinking when either the voltage or current drops low. Therefore, a low voltage battery will trigger the blinking and so does low current when using a low drain battery. If you have a cc/cv power supply with adjustable voltage at least up to 4.2v and current at least up to 3A, you can tap that to the light and find out exactly how to trigger the side led's blinking behavior.
 

vladax

Newly Enlightened
Joined
May 4, 2013
Messages
8
Sorry, I made a mistake. After more investigating I have discovered that the red light is flashing only in the standby mode. This corresponds to the manual.

I'm convinced that the slow flashing has nothing to do with the battery and it's power.
 

vladax

Newly Enlightened
Joined
May 4, 2013
Messages
8
Today I have discovered a design flaw in this amazing light. When the power switch is ON the mode can be VERY EASILY changed using an external magnet regardless the mode selected on the ring.

Even a very weak magnet is sufficient to change the mode. I my case the mode changes when I put the light closer than 20 cm to a speaker. Try it for yourself.

This leads me to a recommendation:
Do not carry the light in your backpack or pocket on the standby mode. Always turn in off when not in use.
 

aau007

Enlightened
Joined
Sep 12, 2010
Messages
448
I had the light sitting less than 5 inches from my desktop speaker in standby mode and nothing changed.
 

Bigmac_79

Flashlight Enthusiast
Joined
Jun 3, 2011
Messages
1,511
Location
Kansas
Yes, lights with magnetic control ring can be affected by a magnet. I remember having a blast playing with my SWM V10R when I first found that out ;). I don't know if I'd call this a "design flaw", because to add magnetic shielding would likely add a lot more bulk than it's worth. You could design a control ring that used direct electrical connections, but then while it wouldn't be affected by magnets it would loose waterproofness. For most environments I'm in, water is more common than a strong magnetic field, but if you do work around machines that create or are affected by magnetic fields than you wouldn't want a light with a magnetic control ring.
 
Top