As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EMERGENCY LIGHTING SYSTEM TEST SHOWING "EMERG BAT 1 LO" MSG ,DURING COCKPIT POST FLT CHECK. RELEASED FOR SERVICE PER MEL 33-50-04. EMERG BAT 1 LOW MSG DURING TEST. REPLACED EMERGENCY POWER SUPPLY. OPS CHECKS SATISFACTORY. OK FOR SERVICE.