Hello,
The first step is to find the signal, but the very hard work is retrive the equipment form the water.
Sorry for disagree but on the contrary .. the very hard job is to locate the black boxes and the easy (more easy) job is to retrive the boxes from underwater....
So more long life of battery ... more better chance to locate boxes!
BTW .. still 5 days before the batteries are drained .. and the boxes are not yet located....
When this will be no more emissions .. it will be very very hard to find them ..
Regards.