Impossible lumens
Enlightened
- Joined
- Apr 25, 2015
- Messages
- 939
Jetbeam has a new 1X 18650 XHP-50 light out that goes by SF-R28. The SF-R28 has a boost driver to give it's XHP-50 6V off a single 3.7 18650. This light was provided to me by Andrew-Amanda.com for review on YouTube.
The highlights of the SF-R28 are it's output for its size, given it's a single 18650 light. SF-R28 also has a fair measure of throw given that it uses a smaller XHP-50 vs the XHP-70. I also personally like the semi-tactical design with the forward clicking tail-switch. Though the side e-switch for mode switching, is less tactical in nature, it also can make easier mode switching for walks, or any activities if holding the light in the hand for an extended period.
Only ANSI FL1 spec for the following: With my light-box calibrated to give exactly 960 lumens off of the Nitecore SRT7 Revenger using a fully charged high drain 30Q cell, I got 1640 lumens as a result for the new SF-R28 regardless if using IMR or ICR type batteries. I'll just call it 1,600 lumens.
The SF-R28 sustains 1,600 lumens for 1 min. 30 sec. before it will begin to ease down over a period of 45 seconds when it then maintains 850 lumens indefinitely. The light will always go back to it's full 1,600 lumens when clicked off and back on or when cycled through. Also double clicking the e-switch on the side will go straight back to turbo 1,600 lumens without shutting off the light.
SF-R28 does very well with thermal management. 1,600 lumens turbo is prime real estate for a light like this to be used in turbo for extended periods. After 5 minutes of sustained turbo the light was pretty warm but in no way uncomfortable, and not quite what I would call hot yet, for a very unscientific analysis. The light also cools quickly when turned off or switched to lower modes.
At about 3.6V the light cuts out high and turbo modes and only functions in mid and low modes. This basically says that it is time to recharge the light even though it can actually continue for another hour or so in it's 150 lumen low mode. It seemed premature to cut out turbo at 3.6V. However, the light is designed to be optimal for both standard lithium cells as well as high drain, and function the same regardless, so I understand the thinking behind designing the light this way.
The built in charging although better than nothing, only charged up to 4.05V which is sub-par. Charging is 750MA. Given that turbo cuts out at 3.55-3.6V I would have really liked to see a full 4.2V off built in charging. EDIT: If you click the rear switch on when you plug in the USB charger, the light will charge to 4.2V with a good CC/CV rhythm. However, the charge indicator light won't function properly when doing this do just give it a good 4 hours when empty and it will do the rest.
I like the SF-R28 for its size, brightness and it's ease of use. Almost perfect for night walks or even some patrol applications. Glad it has built in USB charging but really wish this was implemented better. My video review is as follows...
The highlights of the SF-R28 are it's output for its size, given it's a single 18650 light. SF-R28 also has a fair measure of throw given that it uses a smaller XHP-50 vs the XHP-70. I also personally like the semi-tactical design with the forward clicking tail-switch. Though the side e-switch for mode switching, is less tactical in nature, it also can make easier mode switching for walks, or any activities if holding the light in the hand for an extended period.
Only ANSI FL1 spec for the following: With my light-box calibrated to give exactly 960 lumens off of the Nitecore SRT7 Revenger using a fully charged high drain 30Q cell, I got 1640 lumens as a result for the new SF-R28 regardless if using IMR or ICR type batteries. I'll just call it 1,600 lumens.
The SF-R28 sustains 1,600 lumens for 1 min. 30 sec. before it will begin to ease down over a period of 45 seconds when it then maintains 850 lumens indefinitely. The light will always go back to it's full 1,600 lumens when clicked off and back on or when cycled through. Also double clicking the e-switch on the side will go straight back to turbo 1,600 lumens without shutting off the light.
SF-R28 does very well with thermal management. 1,600 lumens turbo is prime real estate for a light like this to be used in turbo for extended periods. After 5 minutes of sustained turbo the light was pretty warm but in no way uncomfortable, and not quite what I would call hot yet, for a very unscientific analysis. The light also cools quickly when turned off or switched to lower modes.
At about 3.6V the light cuts out high and turbo modes and only functions in mid and low modes. This basically says that it is time to recharge the light even though it can actually continue for another hour or so in it's 150 lumen low mode. It seemed premature to cut out turbo at 3.6V. However, the light is designed to be optimal for both standard lithium cells as well as high drain, and function the same regardless, so I understand the thinking behind designing the light this way.
The built in charging although better than nothing, only charged up to 4.05V which is sub-par. Charging is 750MA. Given that turbo cuts out at 3.55-3.6V I would have really liked to see a full 4.2V off built in charging. EDIT: If you click the rear switch on when you plug in the USB charger, the light will charge to 4.2V with a good CC/CV rhythm. However, the charge indicator light won't function properly when doing this do just give it a good 4 hours when empty and it will do the rest.
I like the SF-R28 for its size, brightness and it's ease of use. Almost perfect for night walks or even some patrol applications. Glad it has built in USB charging but really wish this was implemented better. My video review is as follows...
Last edited: