I’ve been in and out of the flashlight hobby for a while but this year was the first year I’ve been able to do my own runtimes, using the ceilingbounce app. While looking for a new bike light last fall I got into the Convoy S2, they’re great lights but learning about them takes a lot of digging. I thought it would be helpful to perform and share some runtimes for the Convoy S2.
Convoy S2+ 5000k XPL-HI U6-3A, 7135*8 Biscotti firmware, SMO reflector, AR Glass, Tan Finish
Convoy S2+ 5000k XPL-HI U6-3A 7135*6 Biscotti firmware, SMO reflector, AR Glass, Tan Finish
Convoy S2+ 2700k SST20 J2 7135*8 Biscotti firmware, SMO reflector, AR Glass, Grey Finish
I used a Xtar VC4S charger and all batteries were tested and found within 3% of nominal value.
16340: Imren 700mah
16340 Protected: KeepPower P1634C 700mah
18350: Epoch 1100mah
18650: Sanyo NCR18650GA 3500mah
18650: Samsung 30Q 3000mah
Here’s a link to the graphs I created for reference.
100% runtime comparison for Sanyo NCR18650GA and Samsung 30Q
40% runtime comparison for Sanyo NCR18650GA and Samsung 30Q
100% runtime for all models and battery types
40% runtime for all models and battery types
And here’s a link to the spreadsheet so you can make your own graphs or change the parameters for different comparisons. I think the lumen values are a good approximation - based on comparing to other third party results and the LED datasheets. I’m currently working through the runtimes for the newer SST40 5A driver and will post up when it’s done. So I hope this is useful, thanks for checking it out!
Thanks for sharing the measurements. The regulation time for the older cree LEDs with their high Vfs are not great. It’s hard to have regulated output with those (XPL, XML2) without going to a buck/boost driver. Newer LEDs with much lower Vf are regulated much better with linear drivers. Are you testing an SST40 with the new 5A driver?
Yes definitely, I don’t have many comparable lights but I do have an older Rofis TR20 with XPL-HI and it will maintain a regulated output of around 250 lumens for 5 hours and 600 lumens for 90 minutes before it drops instantly to moonlight. Of course, it also cost 4x as much
Don’t know if that light uses a buck boost driver, but in general regulating at lower current levels is more doable. The 7135 drivers don’t even regulate in lower modes well because they use PWM to dim. But the convoy linear drivers use constant current for all lower modes so it regulates better.
True. The linear drivers with fets are much better at regulation in lower modes and have no noticable pwm. I noticed something interesting though with the 5A 12 mode driver in a light I built yesterday…at 100%, I noticed a high pitch sound from the driver, faint but noticable. Is it using pwm for the high mode and not direct drive?
I’ve added the runtimes for the SST40 5A FET Driver, it’s pretty impressive. With a NCR18650GA cell the light puts out ~1200 lumens for the first three minutes and then drops to right under 600 lumens, over the next 90 minutes it steadily increases brightness to 875 lumens before the drop over the next 10 minutes, when it hits the 2.9v LVP.
The 40% runtime is probably even more impressive
It instantly boots the rest of my S2s from consideration for bike lighting needs! This light is awesome, when I can afford it I’m planning to request a SST20 version, as well as order some of the 3/5 XML2 models to test. Thanks for looking and for the kind words.
That is probably the thermal stepdown on that SST40 driver. Then as the cell voltage drops, the driver produces less heat so it slowly increases the current until it drops out of regulation. The temperature protection can be disabled by removing a single component.
For biking I really like the other convoy linear driver which is configurable. You can choose any current you want up to ~8A to maximize the brightness for your ride.
Thanks for the test, very useful data to have. much appreciated.
question for everyone who is reading:
Can this process be automated entirely on the electronics side? i.e. you pop in the battery and LED and the system automatically runs, measures, stores data, puts out graph, etc? Ideally without expensive devices.
The ceilingbounce app does already but with simplified graphs, example below. They auto-generate and are saved to a specific folder on the device, as well as CSV file with the data.
I’m ok with the temperature protection as it does not seem to have too much affect when running at 40% on my bike. 100% so far is just for fun
I am slowly working on my mod skills and have ordered two 8A drivers to try. Sometimes it would be nice to have a mode between 50% and 100% for rain/mtb where more light is needed but not 100% with stepdown.