I use all three batteries all the time.
Even after 3 hours the ignition module doesn't even get warm.
I checked the batteries I removed yesterday when it started missing hits and they all had just 1.09 volts remaining.
These really need the 3 fresh batteries.
Three new batteries.... I think.... should be good for 6 hours strong running.?
Perhaps some could keep a battery run time in use log and let us know the voltage and total run time as they weaken.
Gil