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Thanks to Acebeam for providing the T25 for review.
Video Review
Below is a video review of the T25. Due to my old image hosting site closing down, I've got new restrictions on image uploads and have replaced the "Construction" section of my reviews with a more detailed video review.
This video is available in 1080p HD, but defaults to a lower quality. To select the playback quality click the settings button (looks like a gear) after you've started the video.
Manufacturer's Specifications
Price: ---
Plus, here's a few shots with some good detail.
User Interface
See the video for a complete description of the user interface.
Action Shots
You can click on any of these shots to see them full size.
Light in Hand
MugShot
BeamSlice
White Wall
ISO 100, f/3.5, 1/20"
Indoor Shots
ISO 100, f/3.5, 1"
Outdoor Shots
ISO 100, f/3.5, 2.5"
Long-Range Shots
ISO 100, f/3.5, 15"
Performance
Submersion: I submersed the T25 under a foot of water for about an hour, clicking the switch several times. I found no evidence of water entering or damaging the light.
Heat: The T25 gets hot quickly on it's highest output mode, especially when using IMR batteries. After about 5 minutes though, it does an automatic decrease in brightness, and the temp drops down to just being warm.
Drop: I dropped the T25 from about a meter onto various surfaces (including grass, carpet, dirt, and hard wood), and found no cosmetic or functional damage.
Reverse Polarity Protection: Acebeam claims reverse polarity protection for the T25, so I tried inserting the batteries backwards and pressing the buttons, then correcting the batteries, and I can see no evidence of damage. However, because it uses two cells in series, you'll still want to make very certain the cells are both pointing the same direction!
Over-Discharge Protection: The T25 experiences flickering and a sharp decrease in output as the batteries get low, so that's your signal to change or charge the batteries.
Spectral Analysis
All light that we see as white is actually made up of several different colors put together. The relative intensities of the different colors in the mix are what determine the tint of the white we see. For example, cool white LED's have a lot of blue, and warm white LED's have more red or yellow. This measurement was done on a home made spectrometer. The plot below the picture is corrected for the spectral sensitivity of the human eye. Note: the peak in the 900nm region doesn't really exist, it's a piece of the second-order spectrum that's showing up here because of the high intensity of the light source.
Output and Runtime
ANSI FL-1 runtime ratings are the time it takes for a light to fall to 10% of it's original output (counting from 30 seconds after turning the light on).
The vertical axis of the graphs below represents a relative brightness measurement using a home made light box. The horizontal axis is time in hours:minutes:seconds. Runtimes are stated in hours:minutes:seconds. These graphs may be truncated to show detail.
Mode Comparison
Turbo
High
Mid
***NOTE*** The Turbo mode data was collected using a different battery type than my normal testing batteries, due to the requirement for extremely high current (it needs IMR li-ions instead of just ICR). These batteries were un-protected, so I stopped the test shortly after acquiring the necessary data and did not allow the batteries to run down. The data for the other modes was collected using my standard testing batteries.
Throwing Distance
ANSI FL-1 standard for stating a light's throwing distance is the distance at which the peak beam intensity (usually at the center of the beam) is 0.25 lux. I calculate throwing distance and candela (lux at 1 meter) by measuring peak beam intensity at five different distances and using the formula lux*distance^2=constant.
NOTE: for this throw test, I used IMR batteries to achieve the T25's maximum potential.
Note: A calibration factor of ~6.88% has been added into my throw measurements starting on 9.11.14. To compare the throw of a light I reviewed previous to that date, multiply the candela value by 1.0688 to get the corrected value.
Notes
The T25 is built for 2x26650 batteries, but has an adapter sleeve included for the use of 2x18650 batteries (same length, smaller diameter). However, standard 18650 lithium ion batteries can't supply the necessary current to get to the max output. Standard li-ion chemistry uses cobalt (ICR), which gives higher capacity but lower discharge rates. I'll be testing the T25 with manganese chemistry batteries (IMR) for higher discharge but lower capacity.
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