SB001 Super Light Battery – SL8 Battery Incident
Date Released: November 8th, 2022
Subject: SL8 Battery Incident
Required Action: None at this time – Alert
Freefly recently had an SL8 battery fire at our East Coast office. The root cause of the fire is unclear at this time and Freefly is investigating with maximum urgency. While we discover the root cause of this issue we are asking users to be diligent about storing batteries safely and letting Freefly know if any abnormal function is observed with SL4 or SL8 batteries.
As of now, there are no required actions and customers are advised to continue normal SL4 / SL8 / Astro operations with extra attention paid to any battery faults.
This is the context for the incident:
- This was a production SL8 Air battery that had been flown and charged several times
- The battery was fully charged and put away for storage
- The fire originated on the BMS PCBA and not from the Lithium-Ion cells themselves
- The heat caused a few of the cells to vent but the fire did not catastrophically spread through all the battery cells
- We have over 5000 hours of flight time on more than 1000 SL8 batteries (our test fleet plus shipping fleet) and this is the first issue of this type we have encountered
There are a few potential root causes we are investigating:
- Overvoltage incident causing a component to fail and short the pack causing BMS to catch on fire
- From Astro or accessories
- From manufacturing
- From charging
- Cell balance circuit failure or balance wire short circuit
- Manufacturing error or defect in a PCBA
- Random and catastrophic failure of key component (TVS Diode, Regulator, etc)
At this time, there is no immediate action required from our customers.
If you have any abnormal battery behavior during use, charging, or storage, please contact Freefly Support to provide information on the issue. As always, use best practices when charging and handling batteries. And store them in a safe place, away from living spaces and flammable materials.
Next Steps: Freefly will provide an update to this Service Bulletin by 11/14. We will follow up with all SL8 / SL4 / Astro customers on our investigation findings and all required customer actions that come from our investigation.
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