To ensure the longevitity of your systems with rechargable batteries, it is very important that you remove the batteries if you either:

1. Will not play the system for a long time
2. Haven't played the system for a long time

First and foremost, rechargeable batteries have a limited lifespan. Over time, as you repeatedly charge and discharge the battery, the chemical reactions within it degrade the internal components, resulting in a gradual loss of capacity. This means that the battery will hold less and less of a charge, eventually reaching a point where it no longer provides enough power to sustain gameplay for any meaningful duration. By removing the battery, you eliminate this issue entirely, ensuring that your console will continue to function reliably for years to come.

But that's not all.

Battery swelling is a phenomenon that can occur in rechargeable batteries, particularly in lithium-ion batteries commonly found in portable electronics like smartphones, laptops, and gaming consoles. Swelling refers to the battery expanding or increasing in size, often in a significant and concerning manner.

The primary cause of battery swelling is the buildup of internal pressure within the battery cell. This pressure can build up for a few key reasons:

1. Overcharging: When a battery is overcharged, the chemical reactions within the cell can produce excess gas, leading to internal pressure buildup.
2. Overheating: Exposing a battery to high temperatures, either through external heat sources or from intensive use, can cause the electrolyte to decompose and generate gas.
3. Battery age and wear: As a battery ages and is cycled through numerous charge/discharge cycles, the internal components can degrade, leading to gas generation and pressure increase.
4. Manufacturing defects: In some cases, battery swelling can be caused by internal defects introduced during the manufacturing process, such as impurities or structural flaws.

As the internal pressure increases, it causes the battery's outer casing to swell or expand outward. This deformation can be visually noticeable and is a clear sign that the battery is compromised and should not be used further.

Continued use of a swollen battery carries significant risks. The increased pressure can lead to the battery leaking, catching fire, or even exploding in extreme cases. Additionally, a swollen battery may not fit properly in the device, creating further hazards.

It's important to immediately stop using a device if you notice any signs of battery swelling and safely remove and dispose of the battery according to local regulations. Replacing a swollen battery with a new, high-quality one is recommended to restore safe and reliable operation of the portable device.