Lights for the outdoors

February 18, 2018

Thrunite TH10 headlamp

My current favorite headlamp is the Thrunite TH10. It uses a single 18650 Li-ion battery, which has become my all time favorite power source.

As of early 2019, this is no longer available, being replaced by the TH10 version 2. Also they have another light, the TH30 with wide spill and higher turbo brightness

My other favorite headlamps are Princeton Tec and Black Diamond lights that use 3 or 4 AA batteries in a separate compartment.

The price is (was) $40 on Amazon, which was a heck of a deal. It uses a Cree XM-L2 emitter. It is available in Warm White (which I definitely prefer) and Cool White.

Run times

It has 5 brightness modes. Only the middle three are normally accessible.

firefly 0.2 lumens, 65 days
low 11 lumens, 107 hours
medium 172 lumens, 9 hours
high 490 lumens, 178 minutes
turbo 750 lumens, 118 minutes
sos 750 lumens, 270 minutes

Note that these run times are more or less useless without knowing what battery these pertain to. Most likely this is the 3400 maH cell that Thrunite was selling at the time they sold this version. So if you use a significantly degraded laptop cell with maybe 1800 maH left in it, you should cut these times in half.

Let's assume the 3400 maH battery and calculate current draw given these times.

firefly 0.2 lumens, 65 days = 2.2 mA (maybe 2)
low 11 lumens, 107 hours = 32 mA (maybe 25)
medium 172 lumens, 9 hours = 378 mA (maybe 350)
high 490 lumens, 178 minutes = 1145 mA
turbo 750 lumens, 118 minutes = 1700 mA

A fellow says that he measured the currents at 1, 25, 350, 1450, and 2700 mA.

So, even with a significantly degraded battery with maybe 1000 mAh in it, you could run in low mode for 40 hours, which is much more important to me than maximum light output in a situation where I am trying to find my way home on a dark night.

How to operate the light

To turn the light on, press the button quickly.

To change modes, with the light on, hold the button down. Normally the light cycles from low to medium to high and back again, ad nauseum. I find the medium mode just fine, and in many cases low does just fine. In fact I just spent hours hiking a difficult trail using just the low setting.

To get to firefly mode, long press when the light is off.

Double click gets you to turbo from any mode.

Double click again (when in turbo) to get to SOS mode.

I am happy, and proud to say that I have never ever activated SOS mode. It is well hidden and we are thankful, oh so thankful.

Dead battery warning

I just discovered this "by accident". When the battery voltage drops to 3.2 volts, the lamp will begin double blinking every few seconds. It seems to continue doing this forever. The light will continue to run and blink, but brightness begins to drop off in a big hurry. They seem to have picked this threshold well and the only thing to do is to change batteries. The following graph is a discharge curve from one of my batteries. This shows voltage on the Y axis, and time in hours on the X. It is clear that once the voltage has dropped to 3.2 volts the voltage is dropping rapidly and there is little if any life left in the cell.

Feedback? Questions? Drop me a line!

Tom's Light Info / [email protected]