These things have different capacity depending on the output voltage. The old Power Runner, for which this is a replacement, claimed 12 Ah at 3V, 8Ah at 4.5V, 7.2 Ah at 5V, 6Ah at 6V, 4.8 Ah at 7.5V and 4 Ah at 9 to 12V. For what its worth, I have two data points on the Tekkeon running a Fostex FR2:
3.5 hours plus, using a 5 GB PCMCIA Toshiba hard drive but not phantom power
5 hours plus using a Sandisk 8 GB CF card and powering DPA 4052 compact omnis at 48V
Jeff