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Building lithium-ion battery pack safety instructions

Published: 20 May 2011
Last updated: 04 January 2023

Battery dangers

  • A shorted lithium-ion battery wire can become white hot almost instantly and can welds to another wire. It will not be possible to remove the wire by hand. Also the event may generate a blinding flash called a plasma.
  • A battery can still ignite even after 10 minutes.

In case of an accident

  • Extinguish with sand. Never use water.
  • A damaged or shorted battery must be placed in a safe area for observation for at least 15 minutes.

Personal safety

  • Keep sand on hand to extinguish.
  • Do not wear rings or metal bracelets, these can cause short circuit and severe injuries.

Safe battery pack building methods

  • Keep metal objects away.
  • Cables can suddenly swing away and cause a short circuit.
  • Don’t let stripped cables hang loose, but tape them temporarily somewhere on or isolate the cable end.
  • To avoid short circuit, never cut several battery wires simultaneously.
  • During wiring, complete a battery connection entirely before making a next connection.

Battery pack issues

  • Prefer to use a safe battery technology. Lithium Manganese oxides and Lithium phosphate cells, which have slightly lower power ratings, are inherently safer if damaged.
  • Even with solder lips, minimize the soldering time.
  • Provide ventilation openings. These are also to release overpressure.
  • Place fuses directly to the battery.

Isolation in between battery cells

The A123 ANR26650 batteries are isolated with green shrink tube. This isolation is too thin to assemble the cells directly against each other; the isolation may be damaged by vibrations, which will result in a dangerous short circuit. So extra isolation is required. During assembly, keep the battery cells apart with a piece of paper and then glue the cells together with silicone sealant. In this way, cells can be cut loose afterwards if necessary.

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