Diode not working at full power

Hi guys, new to the forum.

So I bought a quite cheap 300mW 808nm diode off of ebay rated at 1.8V 350mA (max 400mA) and tried running it with a variable voltage/current module I got from Amazon. I tested the module beforehand for proper functionality and of course set up the current output using my DVM. The module was powered by two 18650 batteries in series giving a voltage of about 8.4V when fully charged. Once all the connections were made and the diode powered up it didn't really do what it was supposed to do, i.e. start burning.

:thinking: I really need some help here because I have no idea what and if I'm doing something wrong, or if it's the diode to blame. I would greatly appreciate any help whatsoever.

Your "voltage/current module" probably has deadly current spikes on startup, like mine does. They're okay for battery charging or general purpose constant voltage, but they're very bad for laser use. Your diode is probably dead.

What are you heat sinking your diode with? What lens are you using for collimation? What is the diode voltage when running? What is the diode current when running?

Well the diode is inside one of those diode housing units. As for the lens, I have no idea of any specifics on it.

The voltage drop across the diode is exactly what the specs showed, 1.8V. Unfortunately I have not actually measured the current through (it never really crossed my mind :shhh