I recently purchased a 2014 model Thrunite T10 for my INCH bag, and naturally, the first thing I did was to test it. I found that the medium mode on the light lasted for much less time than expected – 15 hours as opposed to the manufacturer’s advertised 39. This is terrible; the primary selling point for me was the runtime. Granted, I was using a battery that, after years of storage, had just taken out of the package and charged, so I decided to conduct a more scientific test.

For this test, I am using three Tenergy Centura AA Low Self-Discharge 2000mAh NiMH Rechargeable Batteries. Each of them was put through the “break-in” mode on my PowerEx MH-C9000 WizardOne Charger-Analyzer. They each have tested capacities of 1903-1954 mAh. I haven’t been able to pin down the base capacity of the battery used to determine the rated runtime on the T10. Different sources have reported 2500mAh and 2800mAh. To give Thrunite the benefit of the doubt, I have adjusted the expected runtime to match the batteries I have available, based on 2800mAh.

Mode Advertised Runtime @2800mAh Expected @1903mAh Observed Time to Dim Complete Shutoff
 High (169 Lumens)  1:30 Hours  1:01  1:30  1:50
 Medium (20 Lumens)  39 Hours  24:28 15:00  15:45
 Low (0.2 Lumens)  147 Hours  99:54 n/a  78:15


As you can see, the high mode does its duty and more, achieving an impressive 50% longer runtime than advertised. The low mode reaches 78% of its advertised runtime; not great, but not terrible, either. I can attribute some of that deficit to battery self-discharge. The middle mode is the most disappointing, achieving only 60% of its expected runtime. This, to me, is the most important mode, being the lowest setting with which I could do most work with at night. I purchased this flashlight with the expectation that I could get at least a day straight of runtime at 20 lumens; I need all the time I can get for my solar panel to charge spares in the field.

As it stands, the medium mode is hardly better than that of my $12 Energizer Trailfinder 360 (14 hours with an old, worn 2000mAh battery) which it was purchased to replace. The Trailfinder also seems just a bit brighter on medium, which is rated at 13 lumens; 7 less than Thrunite’s. Thus, I am also now questioning Thrunite’s rated Lumen output, as well. I suspect that it is actually 9 lumens like that of the previous T10 model (which also had grossly misadvertised runtime), but I have no means by which to test this.

Again, giving the benefit of the doubt, I conducted the same experiment on medium mode using a new Duraloop Ion Core which tested at 2403mAh after break-in out of the package, and a new standard Energizer alkaline. Again, expected run times are adjusted for battery capacity.

Battery Capacity Expected Runtime Observed Time to Dim Complete Shutoff
 Duraloop  2403mAh  30:53  19:05  19:29
 Alkaline  15:00  15:30


I contacted Thrunite’s customer support about this, informing them of my results, and asking them how I might replicate their runtime claims. I received the following response the next day:

Dear Walter Heitman,

It could be some discrepancy, but could not be so much.

we usually test with rechargeable Ni-mh battery, I would like to report this issue to related department and get research.

Our lumen values is composed of test and calculations.

And I would respond you further if I got answers .

Best regards,

Sholyn Y. |Service support |ThruNite

I waited a full week without receiving the followup. I requested an RMA and sent it in. Generously, they only asked for the tracking number before sending my replacement. I received it five days later (they sent the wrong color, but I don’t want to have to send it back again) and re-did the runtime test using a Duracell Ion Core battery.

Battery Capacity Expected Runtime Observed Time to Dim Complete Shutoff
 Duraloop  2403mAh  30:53  19:20  19:35


I sent the following:


I received the flashlight. I tested it again using the same Duracell Ion Core 2400mAh low self-discharge battery, and achieved very similar results, 19 hours and 20 minutes of runtime until it dimmed, and another 15 minutes before it went out completely. I do not need another replacement, as I now believe this to be the limitation of the flashlight design, itself. Please pass it up the chain that I do not appreciate being sold a product with performance claims twice that of what it was actually designed to meet.

~Walter Heitman

I waited a week before posting this review to see if they would redeem themselves, but as of yet, have received no response.

I plan to keep the T10, since it is a decent flashlight in its own right and I’m already out almost $40 in costs and shipping both ways. However, if I were to purchase a flashlight in the future, I would definitely look elsewhere. In terms of runtime (which was the only selling point for me), compared to my older Energizer Trailfinder, I basically spent $27 for a white-colored and longer lasting (as opposed to the Energizer’s 50-hour red) firefly mode.

If you’re in the market for a new flashlight and honest runtime claims are important to you, steer clear of the Thrunite T10 (and probably their whole product line) as results fall far, far short of advertised claims.

(I’m through with Thrunite. Ha!)

(Damn, that was an expensive joke.)