You have spare LiPo batteries for your project stored away. You assume they'll be fine, but a nagging thought appears: will they be dead or, even worse, dangerous when you need them months later?
A properly stored LiPo battery can last 6 to 12 months with only minor capacity loss. To achieve this, store it at its "storage charge" of 40-60% (around 3.8V per cell) in a cool, dry place. Storing it fully charged or empty will ruin it much faster.
As someone who manages battery inventory1 for a living, I've seen improper storage destroy thousands of dollars worth of perfectly good cells. For a professional like Jacky, who sources components for medical devices, ensuring that batteries remain stable and reliable after months on a warehouse shelf is absolutely non-negotiable. The reliability of his final product depends on it. So let's dive into the specifics of how to do it right.
Can LiPo batteries catch fire when not in use?
You've heard the horror stories about LiPo battery fires. Now you're looking at the batteries sitting on your workshop shelf and wondering if they are a ticking time bomb, even when just sitting there.
Yes, a LiPo battery can catch fire when not in use, but it is extremely rare for a healthy battery. This typically happens only if the battery was previously damaged, has an internal defect, or is stored in extreme heat. A healthy, properly stored battery is very safe.
The risk of a spontaneous fire, while low, is real and shouldn't be ignored. The cause is usually a phenomenon called thermal runaway. This can be triggered by a tiny internal short circuit, perhaps from a manufacturing flaw or physical damage from a previous drop. This short creates a little heat, which speeds up the chemical reaction, which in turn creates more heat. It's a vicious cycle that can end with the battery swelling and bursting into flames. Storing a battery fully charged makes it more volatile because it holds more energy, increasing this risk. This is why storing at a lower "storage voltage" (around 3.8V per cell) is much safer—there's simply less energy available to fuel a potential fire. As a rule, I always tell people to inspect batteries for puffing or damage before storage. If it's damaged, don't store it.
How do you store LiPo batteries when not in use?
You need to put your LiPo-powered equipment away for the off-season. You know there's a specific way to do it, but you're worried that getting it wrong will leave you with useless batteries next spring.
To store LiPo batteries long-term, use a smart charger to bring them to their storage voltage of 3.80-3.85V per cell. Place the battery in a fireproof LiPo bag or an ammo can, and keep it in a cool, dry place away from sunlight.
This procedure is the single best thing you can do for the health of your batteries. Most modern smart chargers have a dedicated "Storage" function that makes this incredibly easy. It will automatically charge or discharge the battery until each cell is at the perfect 3.8V level. If your charger lacks this feature, you can manually charge a low battery until it reads 3.8V per cell, or run down a full battery until it reaches that point. The storage location is equally critical. Heat is the number one enemy of all batteries. Never store them in a hot attic, a car's glove box, or in direct sunlight. A temperature-stable location like a basement or a closet in an air-conditioned house is ideal. Using a fireproof LiPo bag adds a crucial layer of safety, helping to contain any problems should the worst happen. I also recommend checking the voltage every few months to ensure it hasn't self-discharged too low.
How to keep LiPo batteries from exploding?
The fear of a LiPo battery failing violently is valid. You want to take every possible precaution to protect your home, your workshop, and the integrity of the products you build.
Prevent LiPo failures by avoiding the three main triggers: physical damage (punctures, dents), overcharging2 (wrong voltage or charger), and overheating (charging/discharging too fast). Always use a quality balance charger and store batteries in a fireproof container.
In my experience, almost every battery failure can be traced back to one of these three root causes. Preventing them is straightforward if you build safe habits.
Always Inspect for Damage
Before you charge, use, or store a battery, give it a quick look and feel. Is it puffy or swollen? Does it have any dents or deep scratches? Is the outer wrapping torn, exposing the cell? If you see any of these signs, the battery is compromised. Do not use it. It's time to discharge it safely and take it to a recycling facility.
Use the Correct Charger and Settings
This is non-negotiable. Only use a quality smart charger with a balance function that is specifically made for LiPo batteries. The balance feature ensures all cells within the pack are at the same voltage, which is critical for health and safety. Double-check that you've set the charger to the correct cell count (e.g., 3S for an 11.1V pack) and chemistry (LiPo).
Avoid Extreme Temperatures
Heat kills LiPo batteries. Never charge a battery that's hot after being used, and never use a battery that's hot from sitting in the sun. Let it cool to room temperature first. Likewise, charging or discharging too fast (exceeding the battery's C-rating) generates excessive internal heat, which damages the cells over time and increases risk.
What is the 80% rule for LiPo batteries?
You've heard people in online forums mention the "80% rule" for LiPos. You're not sure exactly what it is, but it sounds like an important trick for making batteries last longer.
The 80% rule for LiPo batteries is a guideline to maximize their lifespan. It means you should avoid discharging the battery more than 80% of its capacity, stopping use when it still has 20% charge remaining.
This is one of the best habits for getting the most cycles out of your batteries. A LiPo battery is technically "empty" when its device's low-voltage cutoff (LVC) engages, usually around 3.0V-3.2V per cell under load. However, consistently running a battery this low puts significant stress on its internal chemistry. It's like constantly redlining a car engine—it will wear out much faster. By following the 80% rule, you stop using the battery when it still has about 20% of its energy left. At rest, this corresponds to a voltage of about 3.7V per cell. This simple practice of not deep-cycling the battery can easily double its useful service life compared to running it until the LVC kicks in every time. It's the difference between gentle use and abuse, and the battery's longevity will reflect that.
Can you bring a dead LiPo battery back to life?
You found an old LiPo battery in a drawer that won't take a charge. You hate to waste it and wonder if there's a way to jolt it back to life.
No, you should never try to revive a LiPo cell that has discharged below 2.5V. At this point, irreversible and dangerous chemical changes have occurred. Attempting to force a charge into it can cause an internal short, leading to fire.
My answer to this question is always a firm and immediate "no." It is one of the most dangerous things you can do with a LiPo. When a cell's voltage drops below a critical point (around 2.5V), the copper anode inside begins to dissolve into the electrolyte. If you then try to force current into it, that copper can re-plate unevenly, forming sharp, microscopic spikes called dendrites. These dendrites can easily puncture the thin separator between the positive and negative sides of the battery, creating a dead short. This is a guaranteed recipe for thermal runaway. Some advanced chargers have a "pre-charge" or "revive" function, but this is only for cells that are slightly below the normal cutoff (e.g., 2.8V-2.9V). It is absolutely not intended for a truly dead cell. The risk of a fire is not worth the few dollars you might save. The only safe action is to dispose of it properly.
Conclusion
A LiPo battery's unused lifespan depends entirely on storage. Keep it at 3.8V in a cool place, and it can last a year. Always prioritize safety: never use damaged cells or try to revive dead ones.
