While the DA-P1 will operate on 6 volts, its actually made to run on 7.2. There have been conflicting reports on whether operating at 6 volts can cause additional wear on the deck. People commonly operate them off 6 volts, because 6 volt SLAs are readily available off the shelf. I've run a DA-P1 in the field off 6 volts for almost 10 years now, whether that resulted into extra trips to pro-digital or not, I can't say.
-Dave