so im still learning about electronics ingeneral and i was just looking at this light in a differnt thread
http://www.intl-outdoor.com/edc-18650-xpg2-r5-xml-u2-900450lm-flashlight-p-522.html
question: what is the benefit or downfall to choosing the driver with higher amperage?
*Nanjg 105C (8*7135) circuit board for the XM-L version, Current: 2.8A
*Nanjg 101-AK-A1 (4*7135) circuit board for the XP-G2 version, Current: 1.4A
It is a flashlight offered with various LEDs ( XML, XPG).
I thing XPG2 led works with 1,5 A max?
XML till 3 A.
Short:
benefit: more light
downfall: less runtime
Long: XP-G2 and XML emit a different beam. XML is more floody and can take higher amperages. Basically, the more amps, the more light. But you get less runtime because the battery will be depleted faster.
Those are pretty normal driving currents for those two LED’s. The XM-L at 2.8A will crank out a lot of light, the XP-G2 will be less. But a battery will last twice as long at the lower current and the light won’t get as hot. Of course, if you get the XM-L, you could always run it on Medium and extend the battery life. But the XM-L on Medium won’t throw as far as the XP-G2 on High.
Hi reiko1078 and welcome to BLF.
The 8*7135 driver is driving a XM-L led that takes up to 3 Amps of current @ 3,7-4,0 volts and give an output of up to 1040 lumens in the highest bin (U2 bin).
The 4*7135 driver is driving an XP-G2 that takes up to 1,5 Amps of current @ 3,7-4,0 volts and give an output of up to 558 lumens in the highest bin (R5 bin).
So the 8*7135 light will give out more but at the cost of run time. Since the current is double that of the other one the run time will be just a bit less than half of the other light. That "bit less than half" is because a Li-ion battery has lower capacity at higher current drain levels. How much is hard to say as it depends on battery brand, age, use, type and perhaps other factors I don't know.
The XML light will also heat up faster. This reduces the leds efficiency and you may experience "thermal sag" which is a term used to describe that a LED likes it cold. When the temperature rises as in when it is turned on it will become less efficient. This is not something that your eyes can pick up as it happens gradually from the moment you turn the light on. But in some lights it reduces output with up to 10% when the light is run in high mode for prolonged periods.
Most lights handle this fine as they have a good thermal path or "escape route" for the heat from the LED to the lights body.
Anyway I think it was a good question and I hope I did not confuse more than help.
And have a nice time here on BLF - I know I do ;-)
Also the bigger led will always be a bit more efficient when using same current
ok guys thanks for the break down!! 