Swollen or Dead Airsoft LiPo Battery: What to Do

A LiPo battery that starts to swell isn't just a sign of ageing to watch from a distance, it's a signal of internal degradation that must be taken seriously straight away. Understanding why it happens lets you react properly on a battery that is already affected, and above all stop it happening again on the next ones.

Why a LiPo swells

• Too deep a discharge, below the minimum voltage per cell, damages the internal structure and generates gas
• Unsuitable charging (wrong charger, wrong current or voltage setting) speeds up that degradation
• Storing at full charge for a long time wears the battery faster than storing at partial charge
• Exposure to strong heat, including in a car in summer, greatly speeds up ageing
• A physical shock or puncture, even a slight one, can damage a cell and trigger swelling

What to do with a battery that is already swollen

A swollen battery must no longer be used or recharged, however small the swelling looks. The risk of thermal runaway rises with continued use of a damaged cell. Good practice is to discharge it fully in a fireproof container if you are confident with a safe discharge procedure, then take it to a battery collection point, never throw it in with household waste.

Good habits for the batteries you keep

• Use a balance charger suited to the number of cells, never a generic charger not designed for LiPo
• Never discharge a LiPo below 3.0V to 3.2V per cell, most chargers and some electronic controllers (MOSFET) let you monitor this threshold
• Store batteries at around 50 to 60% charge (storage voltage) if they won't be used for several weeks
• Avoid any storage in a vehicle exposed to sunlight, even briefly in summer
• Visually inspect each battery before charging, a slight swelling at rest must stop any charging immediately

The link with the replica itself

A battery that ages badly doesn't only affect its own lifespan, it can also speed up motor wear if it struggles to deliver a stable current, especially on replicas fitted with high-performance motors that need sustained amperage. An irregular rate of fire therefore isn't always a gearbox problem, the battery deserves to be tested alongside before concluding there's a mechanical fault.

Safety first, including the carry bag

Carrying LiPo batteries, especially to a field or a competition, is best done in a dedicated fireproof bag or pouch, a simple precaution that limits the consequences if something unexpected happens during the journey, regardless of the apparent state of the batteries carried.

Doubts about a battery's state or its effect on the motor? Better to be sure before the next game. Get a free diagnostic