Why do two-way radio batteries swell?
When two-way radios are in near-constant use – moving between shifts, sitting in vehicles, operating in challenging environments, it’s easy to overlook the condition of the batteries powering them. But when those batteries start to fail, the signs can be easy to miss until the problem becomes a serious safety hazard.
A swollen battery is one of those signs. Knowing what causes it, how to spot it, and what to do about it is good practice. The right chargers, storage habits, regular condition checks, and scheduled replacements as part of a wider maintenance programme make a significant difference.
What causes a battery to swell?
Lithium-ion batteries naturally degrade, and manufacturers usually recommend replacing them every 3 to 5 years even if they still hold a charge.
Lithium-ion batteries contain a liquid electrolyte that conducts charge between the internal layers. Under normal conditions, this works reliably for hundreds of charge cycles. But when something disrupts that chemistry, for example heat, overcharging, physical damage, or age, the electrolyte begins to break down. As it degrades, it releases gases that become trapped inside the sealed casing. That trapped gas has nowhere to go. The result is a battery that visibly bulges.
Four things to be aware of:
- Extreme heat – radios left in vehicles during the summer, stored near machinery that generates heat, or used in high-temperature industrial environments are particularly vulnerable. Heat accelerates the breakdown of the electrolyte and can cause it to vaporise internally, speeding up gas production significantly.
- Overcharging – batteries left on charge indefinitely or charged with units that don’t regulate power output correctly, experience continuous internal stress. Over time, this degrades the battery chemistry.
- Faulty or incompatible chargers – damaged or third party charging equipment often delivers inconsistent power, causing internal reactions the battery isn’t designed to handle. The result is faster degradation and a higher risk of swelling.
- Physical damage – a crushed battery pack, or impact that separates internal layers can cause an immediate short circuit.
How to spot a two way radio battery pack that is bulging
Look for a battery pack that no longer sits flush, a back cover that won’t clip properly, or a device that rocks on a flat surface. A radio running warmer than usual or charging inconsistently is also worth investigating.
What to do if your battery pack is bulging
Don’t press, puncture, or squeeze the bulge:
- Power down the device immediately and disconnect from the charger.
- If safe to do so, remove the battery carefully – do not force it.
- If it isn’t safe to remove, take the device out of service and contact your two way radio supplier or an authorised service centre.
Disposing of a two way radio battery safely
A swollen battery is hazardous waste and should be quarantined immediately. Place it in a fireproof container, a metal box with dry sand, or a specialist Li-ion safety bag and store it outside in a cool, ventilated area away from combustible materials.
Do not bin it, put in your recycling bin or post it. Contact your local council’s Household Waste and Recycling Centre, declare the damage and establish their drop-off process or find a licensed hazardous waste management contractor to collect the battery. The contractor will provide a Hazardous Waste Consignment Note, which will prove that your business is compliant with the UK Hazardous Waste Regulations. You can find out more here.
How to reduce the risk of two way radio batteries from swelling
- Use manufacturer-approved chargers.
- Follow recommended charge cycles.
- Keep radios away from heat sources.
- Build battery checks into your maintenance schedule.
Most swollen batteries are avoidable and catching degradation early is far easier than managing a failure mid-operation.
If you’re seeing reduced battery life, inconsistent charging, or any physical changes to your two way radio battery pack, speak to the Radiocoms team for guidance.
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