from Hacker News

Cooling system leak led to Victorian Big Battery fire

by bjowen on 9/28/21, 10:06 AM with 80 comments

• by aetherspawn on 9/28/21, 10:54 AM

  > "A new battery module isolation loss alarm has been added."

  This is the worst fault possible in an EV 101 scenario right here (touch metal -> instant death), so I'm surprised that with all Tesla's experience, they didn't consider an isolation leak as a serious fault. And I'm surprised that they allow the battery monitoring system to be disabled during servicing, especially the IMD (insulation monitoring device).

• by tomalpha on 9/28/21, 10:47 AM

  An extract from the summary page suggests a few things went wrong, but it seems like the fire was caused by liquid and electricity mixing:

  > ESV found a Megapack cooling system leak caused a short circuit resulting in overheating that led to a fire in a nearby battery compartment, which consequently damaged two Megapacks.

  > There were further contributory factors with the Megapack in question being switched into an off-line service mode, resulting in the protection systems being inactive.

  > A 24-hour delay in connecting the batteries to the supervisory control and data acquisition (SCADA) system also meant there was no active monitoring of the Megapack alarms.

• by dhsysusbsjsi on 9/28/21, 12:11 PM

  Reading this it’s a classic systems failure: multiple defensive barriers gone wrong through poor safety planning. It’s reminiscent of the Victorian ESSO gas plant accident https://en.wikipedia.org/wiki/Esso_Longford_gas_explosion

• by RicoElectrico on 9/28/21, 10:40 AM

  So, they'll have to take note from their nuclear colleagues' playbook? About passive safety.

• by walrus01 on 9/28/21, 1:13 PM

  for people who might say 'oh, but these batteries are so dangerous!'

  How many cooling system leaks (radiator+water pump related plumbing) result in vehicle engine fires per year?

  I imagine the largest insurance companies have reasonably good data on this as a cause of total-loss of a vehicle.

  How many times have you seen in person, or seen a photo of a burned out RV that somebody pushed too hard up a mountain pass without keeping an eye on the engine temperature?

• by userbinator on 9/28/21, 1:44 PM

  From the title I first thought this would be about a battery fire that happened in the late 1800s.

• by spockz on 9/28/21, 10:45 AM

  > There were further contributory factors with the Megapack in question being switched into an off-line service mode, resulting in the protection systems being inactive.

  A short in an offline device? That seems weird.

  > A 24-hour delay in connecting the batteries to the supervisory control and data acquisition (SCADA) system also meant there was no active monitoring of the Megapack alarms.

  So a new pack was installed and connected but not monitored? What is the rationale behind that? Failures shouldn’t happen to new devices?

• by cube00 on 9/28/21, 10:51 AM

  > Shorter connection times to the SCADA system to help alert Tesla with specific alarms.

  Interesting that even after installation Tesla are still involved in operationally managing the megapacks.

• by william2021 on 9/28/21, 11:56 AM

  Short circuit that led to a fire in an electronic component

• by bserge on 9/28/21, 10:45 AM

  Should've used metal flanges instead of plastic heh

• by nraynaud on 9/28/21, 11:01 AM

  how much would you ask to be paid to pressure test the coolant system of a giant bomb in situ?

• by baybal2 on 9/28/21, 12:18 PM

  One advantage of LFP batteries is that they can survive much higher temperatures without degradation.

  If you can make battery packs air cooled, that's a big, big weight saver.