If I set the current with a one set of batteries will it change if I use different batteries if the voltage changes. It will still be in the range of the driver plus diode required voltages.
Cyparagon is correct. Say your voltage drop across your diode is 3V and your supply switches from 8V to 7V. There will be a some spikes during the transition but it should all occur in less than 100ms and thus not affect your diode substantially.
For starters, when experimenting, always have your Digital multi meter in series with your diode monitoring its current. Then you can quickly shutoff your setup in the event of overshoot. Odds are if you fried you diode your driver isn't setup correctly. A digital multimeter would be a good investment if you don't already have one so you don't break any more expensive diodes.
I was using a Simpson meter to setup the current. I only had 400-450ma at one extreme of the pot and nothing anywhere else. I think the driver might of been faulty.