DC-DC voltage converter for flashlight

[Dan Oelke]

We got a flashlight to use as a photon canon. And are having issues driving it.

The flashlight we are using is "LED Lenser P7"
http://www.amazon.com/gp/product/B001AT1F6S

It uses 4 AAA batteries so it needs 6V into it. We got a DC-DC converter specifically this one: http://www.amazon.com/gp/product/B008BHAOQO

And wired it up on the bench and everything seemed fine when we plugged it into a battery.

Then we wired it to a relay on the bot - so that the relay provided power to the DC-DC converter which was then wired to the flashlight. After that - it wouldn't work. Before bagging we found that the DC-DC converter output was only 1.6V instead of the 6V it had been adjusted to. Playing with the adjustement screw did not seem to give any different output.

So - any ideas on what we might have done wrong? I think the polarity was always right for the input to the DC-DC converter. Would have reversing it on accident blown something you think?

Any other ideas? Is there a better/more robust DC-DC converter we should be using?

Our regional starts in a few days and we would like to be ready to swap out the offending part for a quick recovery.

Thanks!
Dan