◎ Heres what Tesla learned from last years Megapack fire in Australia

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The Tesla Megapack battery fire at Victoria Big Battery in Australia last year was a learning moment for Tesla and Neoen.The fire broke out in July while testing the Tesla Megapack.The fire also spread to another battery and two Megapacks were destroyed.The fire, which lasted for six hours, was a “safety failure,” according to Energy Storage News.
An investigation into the fire began just days later and was made public recently.Experts from Fisher Engineering and the Energy Security Response Team (SERB) wrote a technical report saying the fire was caused by a liquid coolant leak.This resulted in arcing within the Megapack’s battery modules.
“The source of the fire was the MP-1, and the most likely root cause of the fire was a leak in the MP-1′s liquid cooling system that caused arcing in the power electronics of the Megapack battery module.
“This causes the lithium-ion cells of the battery module to heat up, which can lead to the spread of thermal runaway events and fires.
“Other possible fire causes were considered during the fire cause investigation; however, the above sequence of events is the only fire cause scenario that matches all evidence collected and analyzed to date.”
Teslarati noted that the Megapack that caught fire had been manually disconnected from multiple monitoring, control and data collection systems since it was in a testing state at the time.Another factor contributing to the spread of fire is wind speed.
The article also notes that Tesla has implemented several program, firmware and hardware mitigations to avoid similar incidents in the future, including improved coolant system checks during Megapack assembly.
Tesla has also added additional alerts to the coolant system’s telemetry data to identify and respond to possible coolant leaks.Additionally, Tesla has installed newly designed insulated steel hoods within the insulated roofs of all Megapacks.
The report details several lessons learned from the Victoria Great Battery (VBB) fire.According to the report:
“The VBB fire exposed a number of unlikely factors that combined to cause the fire to develop and spread to adjacent units. Never have these factors been encountered in previous Megapack installations, operations and/or regulatory product testing. gather.”
Limited supervision and monitoring of telemetry data during the first 24 hours of commissioning, and use of key lock switches during commissioning and testing.
These two factors prevented the MP-1 from transmitting telemetry data such as internal temperature and fault alarms to Tesla’s control facilities, the report said.These factors put critical electrical fail-safe equipment such as high temperature disconnects in a functionally restricted state and reduce the Megapack’s ability to proactively monitor and interrupt electrical fault conditions before they escalate into a fire event.
Since the fire, Tesla has revised its debugging procedures, reducing the telemetry setup connection time for the new Megapack from 24 hours to 1 hour, and avoiding the use of the Megapack’s keylock switch unless the unit is actively being serviced.
Three lessons related to this section.Coolant leak alarm, high temperature disconnect cannot interrupt fault current when Megapack is closed via key lock switch, and high temperature disconnect may be disabled due to loss of power to the circuit driving it.
These factors prevented MP-1′s high temperature disconnect from proactively monitoring and interrupting electrical fault conditions before it escalated into a fire event, the report said.
Tesla has implemented several firmware mitigations to keep all electrical safety protection devices active regardless of keylock switch position or system state, while also actively monitoring and controlling the power circuit of the high temperature disconnect.
Beyond that, Tesla has added more alerts to better identify and respond to coolant leaks, either manually or automatically.
Even if this particular fire was sparked by a coolant leak, unexpected failures of other internal components of the Megapack could have caused similar damage to the battery modules, the report noted.Tesla’s new firmware mitigation addresses damage from coolant leaks, while also allowing Megapack to better identify, respond to, control, and isolate issues within battery modules caused by failures of other internal components (if they occur in the future).
The lesson learned here is the important role of external and environmental conditions (eg wind) on Megapack fires.And also identified weaknesses in the thermal roof design that allowed Megapack to Megapack fire spread.
These resulted in direct flame strikes from the plastic overpressure vents that seal the battery compartment from the hot roof, the report said.
“The battery inside the MP-2 battery module failed and became involved in a fire due to flames and heat entering the battery compartment.”
Tesla has designed hardware mitigations to protect the overpressure vents.Tesla has tested this, and by installing new insulated steel vent guards, the mitigation will protect the vents from direct flame strike or hot air intrusion.
These were placed on top of the overpressure vents and are now standard on all new Megapack installations.
The steel fume hood can be easily installed on existing Megapacks on site.The report states that the vent hood is nearing production and that Tesla plans to retrofit it to the applied Megapack site soon.
The lessons learned here show that no changes were required to the installation practices of the Megapack, with ventilation shield mitigations in place.Analysis of telemetry data within the MP-2 during the fire showed that the Megapack’s insulation was able to provide significant thermal protection in the event of a fire in an adjacent Megapack just 6 inches away.
The report added that before the loss of communication with the unit at 11.57am, the MP-2′s internal battery temperature had risen by 1.8°F to 105.8°F from 104°F, which is believed to be caused by the fire itself.This was two hours into the fire incident.
The report added that the fire spread was triggered by a weakness in the thermal roof and not due to heat transfer through the 6-inch gap between the Megapacks.Exhaust shield mitigation addresses this weakness and has been validated through unit-level fire tests, including those involving Megapack ignitions.
Tests have confirmed that even if the hot roof is fully involved in a fire, the overpressure vent will not ignite.Tests also confirmed that the battery module was relatively unaffected by an internal battery temperature rise of less than 1 degree Celsius.
2. Coordinate with on-site or remote subject matter experts (SMEs) to provide emergency responders with critical expertise and system information.
3. Directly supplying water to an adjacent Megapack appears to have limited effect, even though supplying water to other electrical equipment (think transformers) that has less built-in fire protection in the design may help protect that equipment.
4. Megapack’s approach to fire protection design outperforms other battery energy storage system (BESS) designs in terms of emergency responder safety.
5. The report states that the Environmental Protection Agency said air quality was good two hours after the fire, suggesting the fire did not cause any long-term air quality problems.
6. The water samples show a low probability of the fire having a significant impact on firefighting.
7. Prior community involvement in the project planning phase is invaluable.It enables Neoen to quickly update local communities while addressing pressing issues and concerns.
8. In the event of a fire, early face-to-face contact with the local community is essential.
9. The report states that an executive stakeholder steering committee composed of key organizations involved in emergency response can help ensure that any public communications are timely, efficient, easily coordinated, and thorough.
10. The final lesson learned is that effective coordination among on-site stakeholders allows for a quick and thorough post-fire handover process.It also enables the quick and safe decommission of damaged equipment and the rapid return of the site to service.
Johnna currently owns less than one share of $TSLA and supports Tesla’s mission.She also gardens and collects interesting minerals, which can be found on TikTok
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