[selfbuilt]

AltusLumen PAD-L Review: Portable Flood Light

Reviewer's Note: The PAD-L was provided by AltusLumen for review.

Warning: Pic heavy

AltusLumen is new company making portable integrated LED lighting tools that don’t use a traditional flashlight design. According to their website, there focus is on eco-friendly designs and energy-efficient approaches. Reviewed here is the PAD-L, a 4-LED emitter setup that runs on 4xAAA batteries. A similar model (TRI-L) is also available with built-in rechargeable Li-ion pack and optional solar charger.

The PAD-L has a MSRP of $40.



Included inside the hard cardboard box are the PAD-L unit, instruction manual, and carrying case. The case is nylon and fairly high quality (comes with two separate zippered compartments, belt loop, and keychain split-ring attachment). The information in the instruction manual is clearly presented, with lots of pictures of the unit. Also included in the package is a headphone cable manager tool (although I’m not really sure why).







The unit has a very unusual build, and is clearly designed to be a flexible flood light. It has an anodized aluminum external casing, including a front cover that is attached by a flexible hinge that allows the light to be positioned in a number of ways. Also included is a rotating bar on the front of the unit that allows for additional positioning.

Note that my unit has a dark blue-black external aluminum housing with gray interior, but the reverse color scheme is also available.

Weight: 96.3g
Dimensions: 65mm x 110mm x 15mm



I find the overall dimensions, ergonomics and size reminiscent of the early iPods. To show you a modern equivalent, you can see below that it is not much bigger than my Blackberry Curve 8310:



The light uses 4 AAA-sized batteries, keeping overall weight down. These are loaded into a battery compartment on the front of the light, that is held closed with a screw. Note that you don't necessarily need a screwdriver to undo the retaining screw - the head slot is wide enough so that small coins also work well (e.g. pennies, dimes, nickels and quarters all worked for me ). Battery compartment has an o-ring, and there seems to be a good seal when the cover is fully tightened down.



User Interface

The unit is activated by a side switch. Switch has a fairly typical electronic switch feel (i.e. think of the button feel on a flat-screen LCD). There is also a red LED located above the switch, which will warn you when it is time to replace the batteries.

The light has 4 output levels and a strobe mode (0.5 sec on, 0.5 sec off) available at each output level. The manual identifies the output levels as Long-Life, Low, Med, and High.

I have measured the PWM frequency of the lower output modes as 180 Hz.

User interface is pretty simple: press and release the switch to turn on at the lowest output. Pressing again within ~ 8 secs advances the light to its next output level (a pause longer than 8 secs and a press will turn off the light). After the max output mode, the light turns off. Note that you don’t have to count the time – the red LED on the side illuminates when the switch is first pressed, and says lit as long as you are within the output level setting time.

To access the strobe mode, press and hold the switch for 3 secs. To return to steady output, press and hold for another 3 secs.

There is no memory mode.

NOTE: The PAD-L has a low-voltage sensor that shuts off the light when ~1V is reached. This will prevent you from over-discharging and potentially damaging your NiMH cells. The side-mounted red LED will come on to warn you when the battery is running low. In the last 1 minute or so of power, the main LEDs will also begin to flash intermittently. Scroll down for output/runtime plots.



I don’t know what sort of emitters AltusLumens is using. As you can see above, the four emitters are mounted flat on a recessed tray that is reflective.

UPDATE: AltusLumens confirms these are half watt Nichias. I don't know which model specifically.

Below are some beamshot comparisons to the Zebralight H50 headlamp (which is all flood with no reflector). The Zebralight is on max on a 1xAA Sanyo Eneloop, PAD-L on 4xAAA Sanyo Eneloop. Distance is about 0.5 meters from a white wall.

f3.2, 1/10sec


f3.2, 1/25sec


f3.2, 1/100sec


f3.2, 1/800sec


I would rate the overall tint of the four emitters on my specimen as creamy-yellow for cool-white emitters, but I don’t know how representative that is. Beam pattern is smooth and even, with no signs of rings or artifacts. I would say it makes a good general illumination source for a small area, as it was clearly designed for (i.e. very floody).

UPDATE: AltusLumens claims the relatively warm, creamy-yellow tint is typical for these emitters.

Testing Method: All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for the extended run Lo modes which are done without cooling.

Throw values are the square-root of lux measurements taken at 1 meter from the lens, using a light meter.

Throw/Output Summary Chart

Below, I’ve compared characteristics of the 4xAAA PAD-L to three 1xAA lights that can tailstand and function in full flood mode (i.e. no reflector present – as in the Zebralight, or with a removable head/reflector – as in the X2 and TL-1).



The PAD-L is definitely brighter on max than most 1xAA lights. Its lowest output mode is also fairly comparable to the 1xAA lights listed above.

To allow you to better compare all the output levels, here is a summary for the PAD-L versus the Zebralight H50:



Output/Runtime Comparison:



I’ve plotted all the runs together above, on both alkaline (Duracell) and NiMH (Sanyo Eneloop, 800mAh). I haven’t tested energizer L92 lithiums, but I imagine they would work well.

The PAD-L shows impressively flat regulation on both alkaline and NiMH (with longer runtime on the higher-capacity NiMH). Output levels are directly comparable between the two battery types.

The PAD-L has a low-voltage cut-off feature, to protect your rechargeable cells. Like the LiteFlux LF5XT, the PAD-L appears to cut-off once ~1V is reached. As a warning, the red LED on the side of the unit comes on and starts blinking when you only have a few minutes left. The main white LEDs will also begin flashing during the last minute or so of power, so you had best switch down to lower output levels if you don't want to find yourself in the dark.

Note that once the light shuts off, you can still re-activate at a lower level if you wait a few seconds for the voltage to rise above the cut-off. I did this several times, and got several more minutes of power at Hi (and you could potentially get a lot longer at the lower outputs).

Potential Issues

You will need some sort of implement to fully tighten or loosen the battery compartment retaining screw. Note that a screwdriver is not necessary, since the head slot is wide enough to accommodate small coins (e.g. pennies, dimes, nickels and quarters all worked in my testing).

Although not overly obtrusive, PWM is detectable on the lower levels (at 180 Hz on my specimen).

This model uses AAA-sized batteries, which have relatively low capacity compared to other battery types.

Button presses didn’t always register in my testing. I found that holding the button down for a faction of a second longer before releasing resolved this issue.

Preliminary Observations

The PAD-L is certainly a fairly unique design in the portable lighting world. I think it serves its intended purpose well, and provides a nice, even flood beam in a flexible format. Although I can’t immediately identify the type of emitters used, color and beam pattern are good on my sample.

I’m impressed with the output/runtime characteristics - it’s rare to see this level of flat regulation on alkaline cells, and with built-in low voltage protection. Unfortunately, the low voltage cut-off also occurs on alkaline (where it isn’t really necessary), but at least the unit gives you sufficient warning allowing you to drop down to lower levels for greater runtime (or restart the light afterwards).

I haven’t tested a lot of multiple-AAA lights to compare, but overall efficiency seems pretty good for the rated cell capacity. I am not generally a big fan of AAA-based lights, due to the lower capacity of these cells (except in keychain or headlamps, where size and weight are of critical importance). I suspect the Li-ion based TRI-L would also be a good performer for its class.

Output levels are well spaced, and the presence of a slow strobe makes sense to me in a general-use portable light source (i.e. you don’t really need a tactical strobe here ). But I would prefer that the PWM frequency be higher. I find it disappointing to see some new lights coming out with visible PWM again. I would urge all makers to bump this up to the >1kHz range.

Build quality seems fairly good, although I originally felt that the use of a screw to hold the battery cover in place was a bit excessive. But given that all the small coins I tried are sufficient to fit into the screw head slot and allow you to open the case, it seems likely that this won't be an issue for most. I am sure this helps provide good water resistance.

This is the first time I've seen relatively warm "cool-tint" half-watt Nichias. I am not sure of the exact Nichia model, but AltusLumens claims that the beam tint I am seeing is typically for these emitters. Personal bias, but this is one of my favourite beam tints.

At the end of day, it comes down to what you need a light to do. As a portable flood lamp, I think the PAD-L has good overall ergonomics and circuit characteristics. It is brighter on max than most 1xAA lights on standard batteries, and has impressive regulation. But personally, I would probably be more interested in the Li-ion based TRI-L design for longer runtimes. Note that optional accessories on that unit include a solar charger and external 4xAAA battery compartment. I would also encourage Altus to consider developing a rugged external shell made of rubber/plastic, as I’m concerned the relatively thin aluminum cover could dent or deform under rigorous outdoor use.

An interesting new addition to the portable lighting world.

UPDATE 3/31/09: Having played with the PAD-L a bit further, I've come to the conclusion that the new Nichia emitters aren't really warm-tinted overall. Subjectively, the output seemed slightly warm to my eyes when examining it up close (i.e. in a small room). But when ceiling-bouncing over a wider area, I find it looks slightly cool. I suspect there's yellow-blue tint variation across the individual emitter beams - i.e. cooler in the center, warmer in the spill (something like the reverse of the GDP emitter). It was just hard to tell originally due to the multi-emitter setup in the PAD-L. Either way, it is a fairly "premium" cool white tint. Please see my color rendition and tint comparison for sample pics comparing to other emitters.