DC to DC adapters for camera trap

Hello,

I am running a camera trap, where a motion sensor triggers an SLR camera via an Arduino Uno. The SLR in turn fires two flashes with radio triggers. Right now my system's duration is limited by the 3V radio triggers, which last a couple days on two AAA batteries. I've been wiring the triggers to D-cell batteries, but I'd prefer to use 6V or 12V SLA batteries, since that's what the flashes themselves run on. I'm assuming the best way to so this would be with a DC to DC converter. I looked at 6V-3V converters, and I can't decide which output current to choose. There is no datasheet for my flash triggers, so I'm not sure what they can handle. The average level of amps they draw must be pretty low if they can go ~48 hours on 2 AAA batteries (40mA?).

Do you think the following converter would work? Thanks a lot for any feedback!

http://www.newark.com/tdk-lambda/cc1r50503sre/dc-dc-converter/dp/05M6909

DC/DC Converter
DC / DC Converter O/P Type:Fixed
No. of Outputs:1
Input Voltage:4.5V to 9V
Power Rating:1.5W
Output Voltage:3.3V
Output Current:400mA
Approval Bodies:CE / CSA / EN / UL
Supply Voltage:5V
RoHS Compliant: Yes

I think, it;s o'k, efficiency 71-90%