Circuit:

http://imgur.com/YeELiHI

which is identical to the application note in the datasheet (scroll down to
the ME2108A diagrams):

http://img.ozdisan.com/ETicaret_Dosy...70_1622138.pdf

(easily translated via Google, but a bit more confusing...)

Measured current at the battery terminals is 275 mA (due to meter insertion
loss its difficult to get an accurate current reading at the LEDs
terminals--the LED dims). Voltage across the LED is a pretty-constant 4v.
Estimating the efficiency of the converter at (roughly) 75 percent the LED is
using 825 mW.

I guess Im looking for a 1W replacement?

Hows my math?

Thanks.