B737 Captain reported aircraft batteries were discharged during the overnight. Communications problems with station maintenance caused additional delays to aircraft departure.

Narrative

I arrived at the aircraft at XA:50 local to start the pre-flight. The aircraft was dark; no power (external or APU) but ground air was hooked-up. I initially thought the jet had been terminated and that I needed to power the jet up so the flight attendants could accomplish their pre-flight checks. I started my safety checks before applying external power to the airplane and when I got to the battery switch it was already on and there was no external power. The DC Volts for the battery read 8 volts. Also; the emergency lights were armed. The Ramp Agent was checking to see how much time we needed to be ready before we started boarding for a departure that was supposed to leave in approximately 45 minutes. I asked her to call maintenance to tell them the battery was dead and asked her to call ops to see if we could get external power hooked into the airplane. Once external was on; their was not enough power from the battery to get power on the airplane. Once maintenance arrived; they tried to get external power on and determined the battery was completely dead and would have to be changed.While maintenance was retrieving a battery; one of the Flight Attendants informed me that when she boarded the airplane; all the emergency lights were illuminated and had went out shortly thereafter. That meant that the emergency lights were running on the individual emergency lights batteries and that they depleted because there was no power on the aircraft. The Captain and I informed Maintenance that the emergency exit batteries had depleted due to the fact they were illuminated and went out while the Flight Attendants were on the airplane. At approximately XB:05 local; Maintenance finished replacing the battery and had power back on the airplane. Part of the Maintenance check list was to make sure the emergency lights worked but not determine how long the emergency lights batteries could last. Maintenance informed us that they were only required to test the emergency lights to see if they worked. Their checklist made no reference to the FAA requirement for the emergency lights batteries to power the emergency lights for a minimum of ten minutes (in case of evacuation). The Captain inquired how Maintenance would determine if the emergency lights batteries were sufficiently charged before signing off the Maintenance Release and they said their was no requirement per their checklist. The Captain called the Dispatcher and Maintenance Crew and Maintenance Crew said there was a minimum requirement of 180 minutes of power on the jet to trickle charge the emergency light batteries to assure a 10 minute charge was available for the emergency lights batteries. Maintenance Crew asked the Captain to write up the emergency lights batteries on the Electronic Logbook (ELB) to break the Maintenance Release so the batteries could trickle charge for 3 hours. About 5 minutes later ZZZ Maintenance signed the write up off and released the Maintenance Release. The Captain called Maintenance Crew back and asked them if that was correct and they reiterated that the batteries needed to trickle charge for three hours and that Maintenance Crew would break the Maintenance Release for the required 3 hours and 'lock out' ZZZ from signing the release until the three hours were up. At XC:00 local the Captain allowed the boarding process to start and contacted Maintenance Crew to sign the Maintenance Release and release the aircraft for flight. The boarding process was completed at approximately XC:40 local and we departed and flew the flight to ZZZ1 uneventfully.