Testing Bulged Lithium Iron Phosphate (LFP) Cells

Introduction

• Brought batteries from brother's place for testing.
• Focus on bulged cells, particularly one that is badly bulged but not vented.

Initial Setup

• Plan to perform capacity tests:
  • Charge the cells.
  • Discharge and measure capacity.
• Using a thermal camera for safety monitoring.

Voltage Readings

• Bulged cell voltage: 3.3 volts.
• Other cells: 3.3 volts, with some at about 0.5 volts.
• New cells rated at 100 amp hours.

Charging Process

• Initial charging: 2 amps, almost 1.8 amp hours after under an hour.
• Thermal camera readings: 33-35°C for charger, battery shows no heat.
• Safety setup: Set thermal alert to 80-100°C.

Day 2 Updates

• 3rd charging session: 24.5 amp hours in 11 hours 41 minutes.
  • Total for 2 days: ~33 amp hours.
• Battery voltage increased slightly from 3.4 volts.
• No visible leaks; shadow observed on tissue paper under the battery.

Discharge Process

• 4th charging session: 2.8 amp hours, dropping to 6 amps.
• Preparing for discharge test outdoors for safety.
• Setup includes:
  • Concrete surface with water for safety.
  • Discharging at 30 amps, about a third of the factory rate.

During Discharge

• First hour: No heat from battery, only from cables.
• After 2 hours: 64 amp hours discharged from 100 amp battery.
• Nearing 3 hours: Still stable, low heat from the battery.

Final Results

• Total discharge: 96-97 amp hours over 3 hours 12 minutes.
• Battery remains resilient despite bulging and prior issues.
• Notable results from other cells tested:
  • Three cells: 83.8, 79, and 77 amp hours respectively.

Conclusion

• Unexpectedly resilient batteries, despite signs of damage.
• Interest in disassembling the bulged cell for further investigation.
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