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Reviews > Lighting > Headlamps - LED > Princeton Tec Byte 2011 > Test Report by jerry adams


INITIAL REPORT - June 13, 2011
FIELD REPORT - September 07, 2011
LONG TERM REPORT - November 14, 2011


NAME: Jerry Adams
EMAIL: jerryaadamsatyahoodotcom
AGE: 57
LOCATION: Portland, Oregon, USA
HEIGHT: 6' 1" (1.85 m)
WEIGHT: 190 lb (86.20 kg)

I started hiking about 45 years ago. My first backpack was 40 years ago. I currently try to do one backpack trip of 1 to 5 nights every month (which can be tricky in the winter). Mostly I stay around Mount Hood, Columbia Gorge, Mount Adams, Goat Rocks, and the Olympic Peninsula. In recent years I have shifted to lightweight - my pack weight without food and water is about 15 lb (7 kg). I make a lot of my own gear - silnylon tarp-tent, bivy, synthetic bag, simple bag style pack.



Manufacturer: Princeton Tec
Year of Manufacture: 2011
Manufacturer's Website:
Listed Weight: 2.26 oz (64 g)
Measured Weight: 2.16 oz (61 g)

Other details:

The Princeton Tec Byte headlamp is an LED headlamp.

Previously I tested a version of the Byte that had a limited burn time on a set of batteries. Princeton Tec has redesigned the Byte. This test is of this new version of the Byte. I will see if this has a better burn time.

The Byte uses 2 AAA batteries. Other LED headlamps I have used have 3 AAA batteries. The 2 batteries of the Byte make it a little smaller and lighter which is a good improvement as long as the burn time isn't reduced too much.

The Byte has two LED bulbs - a dim red bulb and a brighter white bulb. The red bulb is good if I want a dim light that maximizes battery life and minimizes desensitizing my eyes if I want to be able to see without the light. The white bulb provides more light for better visibility.

Red LED on:


White LED on:


The lamp rotates so I can see better at long distance for trail walking, or I can see better at close distances. The lamp rotates easier than other LED headlamps I have used, which has been a criticism of mine.

Byte - pointing forward for hiking. The pushbutton is on the top, battery door towards bottom of picture:


Byte - pointing down for close up lighting:


There is a pushbutton to turn the light on and switch between modes. Push the button and the red LED comes on. It didn't make any difference whether I tapped the button as quickly as possible or held it down for a number of seconds. Push it again and the white LED comes on in a low intensity. Push it again and the white LED goes to high intensity. Push it again and the light goes off.

According to the Princeton Tec website - burn time with alkaline batteries:
high 2 hours
low 96 hours
red 146 hours

On the package its says the same thing except high is 80 hours.

According to the user manual, burn time is calculated as the time it takes for the light to produce at least 0.25 lux at 2 meters, which is equivalent to a full moon on a clear night. This is quite dim and not very usable. I think it would be better to use a much brighter level as the minimum usable, but that would make the burn time much shorter. I think other LED headlamp manufacturers use a similar dim level for specifying burn time.

A better measure of lifetime is this data from the outside of the package:
When the light is first turned on high it's good for 30 meters (90 feet), low - 15 meters (45 feet), and red - 6 meters (18 feet).
After 30 minutes: high - 20 meters (60 feet), low - 15 meters (45 feet), and red - 6 meters (18 feet).
After 10 hours: high - 8 meters (24 feet), low - 10 meters (30 feet), and red - 5.5 meters (16.5 feet).

Interesting that after 10 hours, if left on high, the light will be a little dimmer than if left on low.

Other LED headlamps I have used also have a flashing mode, but I have never found that useful.

The pushbutton operates easily. On other LED headlamps I have used, it is difficult to push the button hard enough. My testing will determine if the pushbutton operates too easily and comes on when it's in my pack.

The button is a rounded rectangular shape with one corner cut off. At the top are 5 little bumps. To push the button, I have to push right where the 5 bumps are. Pushing at other places on the button didn't do anything. Mostly this is a "so what", except a number of times I pushed the button without effect, until I figured out where on the button to push.

Another criticism of mine about other LED headlamps, is that when I first push the button, it goes to high intensity, but since I normally use low intensity, it would be better if it went to low intensity first to reduce the number of times I have to push the button.

The Princeton Tec Byte attempts to fix this problem (if they even knew there was a problem to fix) except, that with other LED headlamps, if I leave the light on for a while, and then push the button again, it turns off. With the Byte, it always goes through the same sequence - red, low, high, off,... regardless of how long I wait between steps, so it doesn't really matter that it starts with the dimmest mode, which I assume I'll use most, I have to push the button a total of four times to turn the light on, then off.

This is minor and many people won't even notice. Also, since the pushbutton is easy to actuate, it matters even less.

The battery compartment door opens easily. Other LED headlamps I have used have difficult to open doors. My testing will determine if the door opens too easily - when I don't want it to open.

Battery door open, batteries partially out:


As you can barely see in the above photo, on the inside of the battery door there is a "+" and a "-" indicating battery polarity. The previous version didn't have this, making it difficult to know how to insert the batteries. It's nice that Princeton Tec fixed this minor problem.

The headlamp is black and gray plastic. The headlamp head strap is elastic - black, white, and red. The head strap is long enough to go around my head with enough extra length so I could adjust it looser if desired. Another LED headlamp I have used had a strap that was just barely long enough.

The Byte is advertised to be able to use lithium batteries. I have noticed that some other LED headlamps warn not to do this because the slightly higher voltage might hurt the unit. Lithium batteries last about twice as long and weigh a little less. The Byte came with standard alkaline batteries which I will use to test burn time. Then I will use some lithiums for the rest of my testing.


The packaging is difficult to get into - good for avoiding tampering, bad for possibly damaging the light when I break into it - no big deal though.

There's a user manual in English, German, and French.

As far as testing goes, initially, at home, I'll carefully see how long the batteries last to see if the problem of limited burn time in the previous version is fixed. Then I'll use some Lithium batteries on a number of trips to see how well these work in real life.


The Princeton Tec Byte looks like a really nice LED headlamp.

The two AAA battery format results in a very light weight.

The headlamp works well. The switch operates easily but not too easily. The battery door opens easily but not too easily. The head swivels nicely.

I can't wait to see how it works in the field.

Look forward to my Field Report in about two months.

Thanks to Princeton Tec and for letting me test this.



June 20, 2011 I did a burn time test with the alkaline batteries that came with the Byte. The batteries tested fully charged with a volt meter and had a March 2017 expiration date so I think those batteries were good. I turned on the headlamp to low white for 8 hours at night at about 55 F (13 C) and then left them off during the day. I repeated this for a number of days until the batteries were dead. After 24 hours, I noticed that at the end of the 8 hours the red LED didn't work at all but after sitting during the day the battery recovered a bit so the red LED worked again. Over 52 hours, the low white level got gradually dimmer but still usable around camp (I could see things at my feet, about 6 feet (2 meters) away from the light). For 2 more hours, the low white level was so dim that it probably met the 0.25 lux at 2 meter spec that Princeton Tec uses for the burn time spec, but it wasn't bright enough to see things around camp.

I replaced the batteries with Lithium batteries. The headlamp with batteries weighs 1.9 ounces (53 grams). It seems to work just fine.

July 1, 2011 - 4 day backpack on Mount Hood in North Central Oregon. Used the Byte for one hour.

July 20, 2011 - 5 day car camp on Southwest Washington coast. I go to bed before it gets very dark so I used the Byte only a little

August 27, 2011 - 5 night trip around Mount Hood in North Central Oregon. 50 F (10 C) at night. I used the Byte for a couple hours total. One night at 1AM I had to put up tarp because it started raining. Low intensity white worked great including looking around for some large rocks.


In my burn time test, on the low white setting, the Byte was bright enough for using around camp (I could see things at my feet about 6 feet (2 meters) from the headlamp) for 52 hours. The burn time spec is 80 hours. It didn't meet spec, but it came close enough for me to be a usable headlamp. Princeton Tec has fixed the problem on the previous model that when you pressed the on/off switch it quit working.

The burn time of the Byte is about 1/3 of 3 AAA LED headlamps I've used. If I was going on a long trip where I needed more than 52 hours of burn time it would be better to use a 3 AAA LED, but I rarely use a headlamp more than 10 hours per trip. The cost of batteries over time will be about twice with the Byte compared to 3 AAA LED headlamps but this cost is negligible. The Byte weighs about half an ounce less than 3 AAA LED headlamps but that weight reduction is small. The Byte costs less than most other LED headlamps. The cost and weight leads me to think the Byte is a pretty good option especially if weight is my most important criteria.

Another factor about burn time, is that on high, with new batteries, the Byte takes only about an hour before it dims to the same level as low. If I wanted a super bright headlamp for nighttime trail finding the Byte wouldn't be so good. I just use a headlamp around camp where a fairly dim level is all I need so the Byte works fine.

With fresh Lithium batteries the Byte is very bright. Red is sufficient for in camp use. Low is bright enough for trail walking.


Princeton Tec has done a great job in fixing the problems with the Byte that I encountered in the first test. Mainly, it now has a usable burn time close to the speced value. For this new version of the Byte, I got 52 hours on low with 2 AAA Alkaline batteries. The spec is 80 hours. At the end of life I thought the light was barely bright enough to use around camp.

They also fixed a minor problem that there was no polarity marker to tell which way to insert the batteries.

For the rest of my testing, I'll use Lithium batteries. These should last twice as long and weigh half as much. Lithium batteries also have a slightly higher voltage which made the light somewhat brighter in my opinion. The red light is really bright.

So far, I have only used the light about 4 hours on low. It's summer so I don't get much opportunity. For the long term test I'll be using the light in winter daylight conditions so I'll have more opportunity to use the light. I'll include some night trail walking

Once, I woke up at 1AM and it started raining. I was sleeping "under the stars". I quickly got up and used the Byte to help set up my tarp. This included looking around for large rocks to weight down the corners. The low intensity was plenty bright enough to do this. Looking for rocks, especially, requires useable vision out to maybe 30 feet (10 meters)"?

Everything else about the headlamp is fine - elastic band is comfortable and adjusts nicely, the head rotates well, the on/off switch works great, doesn't accidentally come on when in my pack, the battery door opens easily but not too easily. I have had other LED headlamps that had a head that was difficult to rotate, switch difficult to push, or battery door that was difficult to open.

Overall I think the Byte is a winner. There are many LED headlamps that are equally as good, but the fact that the Byte has 2 AAA batteries rather than 3 makes it a bit lighter than the crowd of other lights.

Thanks for Princeton Tec and for letting me test this.

Look forward to my long term test in a couple months.



Sept 27 - Oct 2, 2011 - trip around Three Sisters in central Oregon, 35 to 75 F (2 to 24 C), 46 miles (74 km), 7000 feet (2100 m) elevation gain. 7 nights total. Batteries dead, had to replace with new ones.

Oct 12 - 19, 2011 - North side of Mount Hood in North central Oregon, 35 to 65 F (2 to 18 C), 30 miles (48 km), 5000 feet (1500 m) elevation gain. 6 nights total. Used the Byte about 4 hours at night including some trail walking. Slept in a stone shelter so I had to use it for about another 4 hours just to see even during the day.


For my first backpack trip in a while, on Sept 27, I got out my Byte and it was dead. I had replaced the batteries with Lithiums June 20. I have noticed that when the Byte is off, and I put it next to my AM radio there is a slight noise, so I suspect that there is a constant drain which is what caused the Byte to be dead after 3 months. To further verify this, I measured the voltage a few times when it wasn't being used and noticed the voltage dropped a little over time.

This constant drain problem is very disappointing. Other LED headlamps I've used don't have this problem. I like to put in Lithium batteries and use it for a year. There is an easy solution though, after a trip turn one of the batteries up-side down. But, if I forget to do this then it will drain the batteries.

Ignoring the constant drain problem, I'm very happy with the Byte. Using just the red light, I can use it around camp, but I prefer the low intensity white. If I wanted to preserve night vision, like look at a star map, then this would be very useful. The low intensity white is great for around camp and also good for following a trail at night. I tried the high intensity white walking on trails, but it wasn't really necessary.

The Byte:



The Princeton Tec Byte LED headlamp is a nice solution to lighting for backpackers that prioritize low weight.

Princeton Tec fixed the problem with short burn time that I experienced in the previous test.

Unfortunately, there's another problem. There's a constant drain on the battery even when I'm not using it. After 3 months of non-use, with Lithium batteries that are supposed to have a longer life, the batteries are dead. I guess that Alkaline batteries would only last 1.5 months. I can work around this by reversing one of the batteries in between uses.

The 52 hour burn time on one set of alkaline batteries, as I reported in the Field Report, is great for my needs. With Lithium batteries the burn time should be closer to 100 hours. This would probably last me one year.

Everything else about the Byte is great - switch works well, the head rotates nicely for close-up or far away viewing, the elastic band feels good. The low intensity white light is fine for use around camp and for walking on trails at night. I could imagine some scenario, like looking for a lost person, where a brighter light would be useful.

A minor complaint is the way the switch works - push it and it goes to red, push it again and it goes to low white, push it again and it goes to high white, push it again and it goes off.

What works better would be to push the switch and it goes to high. Push it again and it turns off. Push and hold and it goes to low intensity and it gradually turns brighter until I let go of switch. If the light is on, and I push and hold, it will gradually get dimmer. Then, in normal use, I would use at very low intensity which is fine for most uses, which maximizes battery life, but allows higher intensity for the occasional time this is required. There's no need for the red light (unless I needed to preserve night vision but needed to look at something occasionally). This may sound too complicated, but in use is very nice.

I will probably continue to use the Byte until the batteries wear out. I'll probably quit using it after this because it's too much of a hassle to remember to switch one of the batteries between uses.

Thanks to Princeton Tec and for letting me test this.

This report was created with the Report Writer Version 1.5 Copyright 2011. All rights reserved.

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