Can someone explain how it is that I can run a flashlight on 2 x CR123A batteries which = 6 volts or just one 18650 = 3.7 volts ? I know it's probably a dumb question but I know nothing about electrical things yet. Trying to learn fast.
PUZZLED-INFO PLEASE
- Thread starter boz
- Start date
45/70
Flashlight Enthusiast
Hi boz.
Most 2x123 lights have a "buck circuit" within the driver. This reduces the voltage closer to the ~ 3.6 Volts needed to drive the LED. When an 18650 is used in place of 2x123's it's open circuit voltage, which is 4.2 Volts fully charged, is adequate to run the light. The "3.7" Volts you see for Li-Ion cells is the "nominal" voltage when under load. Often when using an 18650 in such lights (sorry "torches" :)) they will run longer, but the brightness level may drop after some use, as the cells voltage drops to a level which is less than the ideal 3.6 Volts needed to run the LED at the normal brightness level.
There also are torches that contain both a "buck" and a "boost" circuit. These lights will drive the LED at the same level, regardless of the cell(s) used (2x123 or an 18650). That is because a "boost" circuit (often used in single AA and AAA torches) boosts the voltage "up to" the 3.6 Volt level required by the LED.
Dave
Most 2x123 lights have a "buck circuit" within the driver. This reduces the voltage closer to the ~ 3.6 Volts needed to drive the LED. When an 18650 is used in place of 2x123's it's open circuit voltage, which is 4.2 Volts fully charged, is adequate to run the light. The "3.7" Volts you see for Li-Ion cells is the "nominal" voltage when under load. Often when using an 18650 in such lights (sorry "torches" :)) they will run longer, but the brightness level may drop after some use, as the cells voltage drops to a level which is less than the ideal 3.6 Volts needed to run the LED at the normal brightness level.
There also are torches that contain both a "buck" and a "boost" circuit. These lights will drive the LED at the same level, regardless of the cell(s) used (2x123 or an 18650). That is because a "boost" circuit (often used in single AA and AAA torches) boosts the voltage "up to" the 3.6 Volt level required by the LED.
Dave
45/70
Flashlight Enthusiast
Humm, good point Conte!
I just assumed (uh, oh!) that since he said "can run", that he was referring to LED lights, but maybe not!
Dave
I just assumed (uh, oh!) that since he said "can run", that he was referring to LED lights, but maybe not!
Dave
alfreddajero
Flashlight Enthusiast
Also depending on the light you will get more runtime using an 18650 vs. 2 rcr's. With my ITP C6t for example with two rcr's its bright but runtime is on the short side, with one 18650 i get about 3hrs of burntime with a tad bit lower lumens which for me is something thats preffered.
