Date: 201908
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ramp ZZZ
Aircraft component: DC Battery
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: Taxi
Result: General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: After an uneventful landing and taxi in ZZZ; while we were approaching the terminal; Ramp Control informed us that our gate was occupied and we would need to wait at the Hardstand. After only a few minutes of waiting there was a 'Triple Chime Master Caution' alarm with an EICAS indication of Batt 1 OVTEMP. I correctly performed the associated memory item and ran the QRH to isolate the battery; and reached the end of the procedure. At this time the battery indicated 66degC. Using CRM my First Officer and I decided to monitor the battery temperature while I attempted to call the company via Dispatch; and he was directed by me to call Operations to inquire how long until we got a gate. After two attempts at calling Dispatch on the new phone number (who failed to pick up the phone) I decided I needed a different course of action. I directed the First Officer to contact Operations once again to tell them that we had an escalating situation in the flight deck and would require a gate as soon as possible. I recall the reply from Operations indicating that a gate would be available in approximately 6 to 8 minutes. All of this time I was watching the temperature rise on the battery. I recall from my training; a reference to 'thermal runaway' beginning after 70degC. The battery was now indicating 72degC. The First Officer and I agreed that this had the potential to turn into a fire; and with this threat combined with the fact that we still did not have a gate we elected to declare ourselves as priority handling because we required a gate immediately. I also directed my First Officer; out of an abundance of caution; to roll the firetrucks in case we were to catch on fire. Operations assigned us gate XX and I began an immediate taxi towards the gate. At this time I had determined that there wasn't a need for an emergency evacuation on the ramp and that heading to the gate would be the safest; quickest; and least impactful situation given the circumstances and non-fire condition. The flight attendant was contacted on at least two occasions; firstly while we were on the hardstand (in order to brief her as to the situation); and then she was contacted again while we were taxiing to direct her as to what type of egress I was planning for the passengers. I stipulated that this was not going to be an emergency evacuation however we were looking for an expeditious deplaning through the main cabin door. Additionally I spoke to the passengers over the PA and informed them that I had a developing situation in the flight deck and I would be parking as soon as possible requesting that they take their belongings and disembark through the main cabin door in an orderly fashion; and not to be alarmed by seeing any firetrucks that might be outside of the aircraft. I reinforced that any emergency personnel the passengers saw was simply be there as a precaution. Upon arrival at the gate we performed the shutdown checklist then I directed the FO [First Officer] to go outside to brief the arriving first responders to the situation. He was told to state that we have a battery with suspected thermal runaway and it was to be attended and monitored until MX [Maintenance] could get there. Meanwhile I remained on the flight deck until all PAX [passengers] had disembarked. I wrote up the battery situation in the MX logbook. I called MX (via Dispatch) now for the third time and didn't get through. I tried again and this the fourth time I got through. I looked outside and saw MX personnel had just arrived just as I started speaking with MX Control. I then performed the terminating checklist and went outside to talk with our MX personnel who by this time had disconnected the hot battery and removed it from the aircraft. The first responders left. The crew departed the aircraft leaving it in the hands of MX who stated they were installing a new battery. I would like to see the QRH enhanced concerning the procedure followed for this event. We completed the procedure quickly and reached the aptly labeled 'END'; however it did not offer ongoing directions as to how to deal with a continued over-heating battery as that which we encountered. I recall a situation very similar to this during a sim training or examination event where I was praised for electing to order an expeditious deplaning at the gate rather than an emergency evacuation on the ramp. I understand that an emergency evacuation can lead to injury. If I had a confirmed fire I would've had absolutely no hesitation in commanding an emergency evacuation on the ramp. Although in our situation it would physically have been possible to remain on the hard-stand and ask Operations for stairs and a bus in order to disembark the passengers onto the ramp; I did not feel time was on our side since I had seen a 6degC rise in battery temperature over a couple of minutes. I was considering the safety of my passengers and crew as my top priority.


Second narrative: I was the First Officer operating Aircraft X. After sitting in the Parking area for a couple of minutes; the Master Warning sounded and visual alerts activated. The EICAS displayed BATT 1 OVTEMP. The Captain performed the memory items for the BATTERY OVERTEMPERATURE procedure and we proceeded to use the Quick Reference Handbook (QRH) to complete the procedure to handle the situation. The Captain went to the Electrical Page on the MFD and the battery temperature was at 66 in red. The BATT 1 OFF BUS message was correctly displayed on the EICAS as it should per the QRH. We ended the procedure also as directed by the QRH. At that point; the Captain directed me to contact Ramp Control to determine how quickly we could get into our gate as he was contacting [Company] Maintenance Control. Ramp Control directed me to contact [other airline] Operations to determine when Gate X would be available for us to utilize the gate. [Other airline] Operations indicated the airplane occupying the gate would be pushing in approximately 5-6 minutes. I relayed the information to the Captain. He stated to me he was having a difficult time contacting Maintenance Control. The Captain directed me to contact Operations again to indicate we had a potential emergency and would need an immediate entry to a gate. When I contacted Operations again; I stated while we did not have an emergency right then; it was possible we were going to have an emergency very soon if we were not able to get to a gate and shut the aircraft down. At that point; [other airline] Operations assigned us Gate XX. At this point; the Captain showed me Battery Number 1 temperature had risen to 72' and he was requesting priority handing. I advised Ramp Control of our emergency and they cleared us into Gate XX. We proceeded around the terminal to the gate. At the gate; the Captain instructed me to exit the aircraft and proceed to the nose of the aircraft to brief the [company] Aircraft Maintenance personnel and responders. Prior to opening the battery compartment; I felt the door for any heat. Feeling normal temperatures; I opened the battery compartment door. The batteries appeared normal. I felt Battery Number 1 and it felt warm to the touch. I felt Battery Number 2 and it was cool in comparison to Battery Number 1. At this point; Port Authority Fire/Rescue arrived and I briefed them about our situation. One of the firefighters had a thermal imaging camera and used it to determine Battery Number 1's temperature was approximately 108 F and Battery Number 2 was approximately 80 F. [Company] Aircraft Maintenance technicians arrived and I briefed them about our situation. The Captain arrived on the ramp after assisting the Flight Attendant with exiting the passengers. He also briefed the [Company] technicians with the sequence of events. The Aircraft Maintenance technicians took control of the aircraft and I returned to the flight deck to retrieve my belongings.


Synopsis: EMB-145 flight crew reported a battery overtemp event while taxiing to gate.