Question About LEDs?

[MarkoD]

so i bought this LED "worklight" that ran on 3x AAA batteries(4.5 volts).

i took it apart and hooked it up to a variable voltage power adapter.



so at 4.5 volts it works exactly the same as it did with the batteries..... but as i increase the voltage, the LEDs get brighter.

at 9 volts they seem to be almost double the brightness.

my question is, will the increased voltage wreck the LEDs or something else on it?

is it safe to overpower LED lights?