I have a battery that is swollen and won’t fit onto my radio, why?
All lithium-ion battery packs and cells swell and it is usually an indication that the battery has reached the end of its service life and needs to be replaced. Batteries can also swell as a result of the following conditions:
- The battery has been exposed for an extended time to temperatures above +60C
- The battery has been left in a deeply discharged state for a period of time (i.e. months)
What causes the swelling?
Lithium Ion cells are self contained chemical systems that store energy. The chemical reactions occur within the cell and are part of normal use. These reactions are normal wear out mechanisms that result in cell swell. This is a known and a normal occurrence in rechargeable lithium ion batteries/cells on the market today. As batteries are continued to be used, they will continue to swell. There are two fundamental mechanisms that occur to cause cell swelling.
- Gas generation – gas is created from a reaction between the internal electrolyte and the electrode.
- Physical growth – as a part of normal use, the electrode thickness increases over time.
Are the swollen batteries safe?
Yes, typically when a cell/battery has swollen at end of life, the battery is essentially “dead”. It’s energy has been discharged and it won’t hold a charge.
Why did some of my battery packs split open?
The battery packs split open due to a workmanship defect (poor ultrasonic weld joint) that allowed the cells to continue swelling. Normally a “good weld joint” will only allow the battery to bulge due to cell swell but not split open.
