So I have 2 of these drivers left over from the pair of SRK I joined together. All cells are unprotected laptop pulls of unknown condition. I have one driver out on the test bench to see if I can use it for something else. I have 3 emitters wired in parallel for testing. So from 1 cell it was 3A to the emitter. Ok useable in a single cell light. So I decide to add a second cell in series. Here is where I get lost. 6A nice! no heat on the driver but current is falling fast. Better check the battery voltage. Under load the voltage sinks fast. Ok lets try again. 2 sanyo 18650 freshish charge. 12A to the emitters oh boy those are xml’s on aluminum. Still the voltage sags hard down to 5.8v under load. My meter is only rated for 10A so I didn’t keep it going for too long, but still no heat on the driver. So lets see what will happen if I parallel 2 more cells. 2s2p sanyo 18650, 16A! oh crap some smoke from the 000 resistor at the 3 o’clock posistion in the pic. In all test the low mode went up everytime as well.
What kind of driver is this, I just figured it was a buck driver and at some point it would stop giving current. But I never did find the limit until it was near death. what am I missing here?
Interesting. Sounds like it has the potential to be a good MT-G2 driver. I don't know the answer to your question, but it seems it could still just be a buck driver. Maybe it couldn't deliver the 2S level of current because the LED Vf's were too close to the cell voltages under load.
I'm am amateur. So there is very little I can tell you. It's a N-Channel Enhancement Mode MOSFET. They are usually used in pairs or more. So I'm guessing you have another one hiding somewhere under the the inductor coil. Is there another one and does it have the same label?
These types of MOSFET's have three connections. Source (connects to power source), Drain (connects to load), and Gate (Applying voltage here will allow current to flow to from Source to Drain). The more voltage, the more current. I guess that may explain why increasing the voltage increased the current. I wish I understood more, because it seems your LED's should have been fried. I guess the MOSFET dissipated the excess voltage over the LED's Vf.
Googling shows that the MOSFET you have is used to control motors and such. It is capable of handling maximum voltage of 25 volts and 60 amps continuous. 280 amps pulse. The maximum watts it can dissipate is 62.5 at 25 Celsius and 37.5 at 75 Celsius.
I guess we could look to see how much voltage the MCU can handle. Is the labeling on it readable?
It looks like it would be very difficult to see the traces in the PCB on this driver.
Hopefully, someone that knows what they are talking about jumps in because I'm in over my head at the moment. I'm curious though as this may be a good driver for MT-G2's.
