Thrunite TN4A users - low battery indicator question

sbslider

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I recently received a TN4A, and it seems the low battery indicator is a bit off. I believe I was seeing it flash red a fair amount when I first put fully charged duracell 2650 nimh batteries in it after using turbo mode. Then the problem seemed to go away, and I ran the light for an hour in high mode, and the low battery indicator was blue as expected. Then putting the light in turbo mode made the indicator turn solid red, and would stay this way even in other modes. The light recovers to blue only if the batteries are removed for some time. I thought perhaps one of the batteries is sort of lame, so I have been running them 1 at a time in my Archer 1AV3, and all 4 run on high for 30 minutes no problem. Based on the run time estimates on Thrunite's website, the current draw of the archer on high is about 1/2 that of the TN4A on turbo.

I will say these are rather old nimh batteries that I was able to recondition about 6 months ago for use in my Archer. They appear to have capacity sufficient to meet the published run time specs for the archer.

What is your experience with the low battery indicator? I sent an email yesterday to Thrunite, and usually they are very good responding overnight, but so far no response.

Update: I ran the light with another set of duracell 2650 nimh batteries on high and periodically checked to see if turbo mode caused the low battery indication. At 70 minutes it worked no problem. At 95 minutes, the low battery indicator (LBI)went solid red when I tried to go from high to turbo. Stays red even on low mode. Unscrewed the light 1/4 turn to remove battery power for 2 minutes. Low mode on, LBI light blue. Same for low, medium and high. Went to turbo, LBI stayed blue for maybe 5 seconds, then light stepped down and LBI went red. LBI stays red, even when light off for 2 hours. remove battery for 2 minutes, it resets. And now I can go into turbo for a short time, and the LBI stays blue. :shrug:
 
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proceed5

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Hi SBSlider,
I remembered a year plus ago I faced similar problem with old (year 2013/2014) 2450 mAh cells.
I ran a test with alkaline AA's and the light worked Ok.
And so swapped out the old batteries and replaced with new ones and the problem was solved.
 

jon_slider

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Turbo has a high power demand and only works at high voltage
the voltage to run low medium and high is lower
that is why after using turbo and triggering the LB Voltage indicator, for that mode voltage, the battery will still power lower modes, once you fool the light by resetting its Battery Voltage indicator

I caution you Not to repeatedly fire turbo with batteries that have triggered the LB Voltage indicator
Turbo is not a mode that can be used at all battery voltage levels, it only works when the batteries are fresh

also, NIMH has lower voltage than Ultimate Lithium or Alkaline, so for Turbo use, the higher voltage cells will allow a few more Turbo cycles before Voltage will no longer support Turbo

Turbo should be used only briefly, it drains the batteries rapidly, and I think you are wise to use a rechargeable, as Ultimate Lithium gets expensive, particularly Four at a time :)

I don't own the light, these are just my opinions
 

sbslider

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Thanks for the feedback proceed5 and jon_slider. When I got home today I cleaned the electrical contacts inside the light and found one interface was a bit dirty. I believe the way the light is designed once the low battery indicator triggers, it stays triggered until power is removed for some time. As jon said, I fool the light by resetting the indicator. I ran another test, left the light on turbo for 5 mintues, and the LBI was red. I measured the cells when I got home and they seemed to be a decent voltage still, but I did not write down the value. After the 5 minute test they are measuring just above 1.2V, so they are definitely spent for this charge. I am guessing at the levels of current this light draws, the old batteries are not up to the high currents and keeping capacity.

I hope to get at least 30 minutes off riding with the light, so I will have to see if
a) high is sufficent, is so no problem
b) light light can last 30 min on turbo with these cells
c) get new rechargables.

I suspect in the long run c, but I will cycle these cells in the light a couple times to see if I can recover some capacity at high load currents. Guessing there is nothing wrong with the light which is nice. :)
 

jon_slider

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sbslider;5113985I hope to get at least 30 minutes off riding with the light said:
Specs:
Working Voltage: 2.75V-8

Turbo 1150 lumens /56 minutes
High 550 lumens /150 minutes


four 1.5v batteries in series = 6v
56 minute turbo means that the light is at 10% at the end of the runtime , i.e., the light is at 115 lumens
150 minute high means that the light is any 10% at the end of the runtime, i.e., the light is at 55 lumens.

I suggest you buy or borrow a light meter, and do a test every ten minutes of runtime, so you know what the actual lumens are at 30 minutes on High.

or, just look at this test by selfbuilt and compare your batteries to his:

he says the Turbo should last 50 minutes to drop to half its starting brightness.

happy riding :)
 
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sbslider

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thanks for the advice, I will likely do the latter. I am currently running the light in medium mode all day to see if my batteries will do the 12 hours to step down that selbuilt measured. Thrunite adverstises 14 hours, but that's is with the step down to low and then further decay. I am expecting based on that data to see the red light come on when it steps down to low at 12 hours. I am at nearly 8 hours right now.

TN4A-MedEnePro.gif


After this I will try a high mode test to see how it compares to the data you provided above.

Eventually I need to find an appropriate clamp to connect the light to my bike. then happy night riding :)
 

jon_slider

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thanks for the advice, I will likely do the latter.
.. ..
I need to find an appropriate clamp to connect the light to my bike. then happy night riding :)
LOL
I look forward to learning how many lumens works, ~150 medium or ~600 high

enjoy the ride!
 

sbslider

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I will try to remember to let you know for sure, but I bought this light to use it at either 550 or 1150 lumens while riding. I think 140 is really only good for sort of being seen, not for really seeing the road and such when it is dark and you are traveling at 15-20 mph. For lower speeds it could work ok. I used my Maratac yesterday evening as a bike light at dusk on medium and high modes, and it worked fine. My wife and I were riding a mile or so on a bike path, so it was really more be seen then. Once you get above 10-12 mph thought you really need some photons to look ahead to what is coming.

So I have two sets of four 2650 Duracell nimh AAs. The set in my light now stayed on medium mode (140 lumens according the Thrunite) 13 hours 10 minutes, then the low battery indicator changed from blue to blinking red. The light appeared to stay in medium mode. About 40 seconds later the light output stepped down to what appears to be low mode, and the red light flashing frequency increased. I turned the light off at 13:20 to check the battery voltages. They ranged between 0.95 and 1.1V, so I decided those cells had worked hard enough. Maybe could have gotten another hour out of them, but the one at 0.95V was low enough that I did not want to damage it. I will run the other set over the weekend hopefully to see if/how the data repeats. Then onto high mode at some point.
 
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jon_slider

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I will try to remember to let you know for sure, but I bought this light to use it at either 550 or 1150 lumens while riding.

I look forward to your real world experience. The selfbuilt chart I posted, says turbo lasted him about 50 minutes before it dropped out of regulation like a lead balloon, while High mode lasts over 2 1/4 hours before it drops out of regulation.

Imo the batteries you got 13 hours out of on medium, are fine, selbuilt got 12 hours before the light dropped out of regulation on medium.

one nice thing about the TN4, it seems to be nicely regulated before it drops out..

I hope it turns out to meet your needs well.
 
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sbslider

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If you use Turbo on a fresh charge, with no other modes, and it lasts for less than 50 minutes, when the red light goes solid, I would suspect your old batteries have less capacity than the batteries selfbuilt used in his test.
I would agree with that.

I would add that at least on medium mode, I got an hour more than selfbuilt at a 140 lumen level. Yes, I agree, I did not measure the light intensity, so I don't know for sure how many lumens, but I do know there was a very noticeable drop in light output just after the low battery indicator started flashing.

I think it is likely my old batteries work fine at lower current levels, but may not work so well at currents required for high or turbo mode. I am interested to run a controlled test and see.

I also found it interesting that my light's low battery indicator behaves differently in different modes, or perhaps at different voltage levels. When the light stepped down from turbo to high, the LBI was solid red. Today when the LBI changed to red flashing, the flashing rate was slower at first, then picked up noticeably when the light output decreased. I wondered if I let the light run long enough if the light would just stay on, but I stopped the test before that happened. Also on my to do list is use a set of alkalines and run to the bitter end to see how the LBI behaves at various times. I think I enjoy testing the electronics aspect of my lights as much as I enjoy using them, maybe more . . . . :twothumbs
 

sbslider

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Ran a second set of 2650 nimh today in medium mode, LBI turned red at 12 hrs 50 minutes flashing slowly, but sill in medium mode for output intensity. within a minute the light output stepped down and the LBI started flashing faster.

I have a theory regarding the LBI. When the light steps down from turbo to high, the LBI goes from blue to solid red, and the liight steps down to high mode. When the light is in medium mode, the LBI starts blinking when the threshold is reached, and very quickly steps down a mode. I am speculating when in high mode, when the LBI voltage is reached, the light LBI will start blinking slowly (or maybe stay solid red for a short time) and then step down to medium mode with the LBI blinking slowly. I think there are multiple voltage thresholds within the light for the LBI, and once one is reached it inhibits using the light at a higher mode. Pretty good design for protecting rechargeable batteries if that is the case.

I tried out my theory with the batteries I had just tested and then charged for a few minutes. The light was able to run on high mode for a bit, but stepped down directly to low mode with a fast flashing LBI. Not sure those batteries are the best test of my theory, as the the voltage on the cells was 0.4V lower (after removal from the battery) after the 13 hour run today than after the test I just completed, referenced in this paragraph. The high run test will likely shine some light on this theory . . . . :popcorn:
 

sbslider

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Ran a couple more tests. Tests with nimh 2650 mAh cells:
- One set (or perhaps just one cell) of my 2650 nimh cells can not go to turbo mode. I know this because my other set ran in turbo mode for 52 minutes before stepping down to high mode. I like that :)
- step down from turbo to high results in change from blue LBI to solid red LBI.
- When starting out with a blue LBI, step down from medium to low results in change from blue LBI to slow flashing red LBI with no mode change, then fast flashing red LBI and a step down to low mode.


Tests with Alkaline cells (1-2 yr old kirklands):
- Alkalines last 3 minutes on turbo before stepping down to high mode, LBI change from blue to solid red. Continued running for 40 minutes in high mode, LBI changed from solid red to blinking red, but no mode change. A bit longer (did not time this) the LBI changed from slow blink to fast blink and the mode stepped down to low, no intermidiate step to medium mode. Reset the LBI, turned on in high mode, LBI blue. quickly changed to sold red, then slow blink red, still in high mode. When LBI changed to quick blinking red, then light stepped down to low mode. It appears the light tries to stay in high mode as long as possible (same for medium mode also). The slow bliking LBI is a warning the light will change to low mode soon. then when it does the LBI is quick blinking.

Future plans: Run these used up alkalines in Med mode to see what they have left - got between 4 and 5 hours on medium mode before light stepped down to low mode. Not so bad considering I used it a fair amount on high and turbo prior to this.

, and see if the LBI behaves like it did with the nimh cells - yes, see next section

Also run the light in high mode with the nimh cells to see what I can get out of them: data, set that runs on turbo lasted around 2 hrs, a bit disappointing but they sat nearly 10 years before being revived. The set that did not run on turbo mode also lasted 2 hours to the LBI turning read, and stepped down after the light transitioning to flashing slowly, then fast, about 2-3 minutes later.


and also try to ID the weak cell that prevents one set from running on turbo mode for any real time.



LBI = low battery indicator.
 
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sbslider

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I posted in this thread regarding some recent testing I did with this light, including tests characterizing the behavior of the low battery indicator. Bottom line is the indicator transitions from blue to red for input to the driver of 3.7V or less, depending on the mode. I suspect my setup lends itself a bit to the variation of the measured voltage, as I was measuring the voltage out of a power supply, but not the voltage at the driver. At the currents this light uses the small resistances of the wires I used will likely add a 0.1 or a bit more difference between the higher and lower levels.

I hope it turns out to meet your needs well.

I think it will. I finally got to try it out last night in the dark on my bike, and while the light was a bit jittery, the amount of light on high seems appropriate for my needs. I thought I would really want to use it on turbo, but the difference in lighting is small in this application. Where turbo really makes a difference is in longer distance illumination, not in the 30 or so yards I am trying to light up with this on my bike at night.
 
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CelticCross74

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2650mah NiMH Duracell?? I think ...that I read a couple years ago about some Duracell with this capacity but it turned out to be a bad cell design and nowhere near 2650mah and they were not low drain cells but high drain. For example there are 2700mah NiMH AA's made by Maha under their Powerex brand. I have had a few sets of these cells. I used them for awhile they were expensive so I put them into my battery rotation. They were indeed a high capacity but I do not believe the 2700mah claim. They also drained power like a busted water pipe. Even removing them from the light they drain out just sitting on a shelf. Best thing to do and best cell for the TN4A when it comes to run time and output is the L91 Energizer Ultimate Lithium AA. It is a 3000mah cell that usually comes out of the package above the rated 1.5v per cell.

Eneloop Pro's. Many people still think these cells only charge to 1.2v per cell. In my experience my Xtar chargers charge NiMH's to a full 1.5v fresh off the charger. Sounds like OP just simply has a case of old high drain degraded over time NiMH's. I would actually throw those away. Depending on how much you are willing to spend on cells go L91 or 2550mah Eneloop Pro. The L91 will give you up to 20% more run time. The Pros indeed drive the light to advertised specs. The Pros are also expensive but hold up better than any other high capacity NiMH AA that I know of. My Pros are a year or more old now. NONE of them have lost ANY capacity. Money well spent...
 

sbslider

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glad the range works
hopefully the runtime is practical for your ride length
Running the light on high, I will get plenty of runtime for a few nights of riding. Typically 30 mintues or less to get home. 2 hours estimated by with standard eneloops, that will do just fine . .
 

sbslider

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2650mah NiMH Duracell?? I think ...that I read a couple years ago about some Duracell with this capacity but it turned out to be a bad cell design and nowhere near 2650mah and they were not low drain cells but high drain. ..
The ones I have are nearly 10 years old, but they do OK with the TN4A on high, just not turbo. I also think part of the problem was my cell carrier has a bad spring, did not notice it until recently. A new one is on the way, so I can better evaluate these 10 year old cells then. Regardless, its time for some new ones, but the duracells can be back up if need be . . .
 
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