How Long Can You Leave a LiPo Battery Fully Charged?

Last Updated on November 28, 2023 by Jaxon Mike

Lithium polymer (LiPo) batteries have become very popular in recent years for powering a wide range of devices, from small consumer electronics to electric vehicles. One of the key advantages of LiPo batteries is their high energy density, meaning they can store a lot of power in a small, lightweight package.

However, to get the most out of your LiPo batteries, it’s important to understand how to properly care for them. One question that often comes up is how long you can leave a LiPo battery fully charged before it starts to degrade.

What Happens When You Leave a LiPo Battery Fully Charged?

When a LiPo battery sits unused at full charge for an extended period, two primary issues can occur:

Oxidation of the Electrolyte

The electrolyte in a LiPo battery is an organic solvent that enables the flow of lithium ions between the anode and cathode.

When the battery is left idle while fully charged, oxidative reactions can occur between the highly oxidizing cathode and the electrolyte. This leads to decomposition of the electrolyte, resulting in the formation of solid deposits on the electrode surface. These deposits interfere with lithium-ion transport, leading to capacity loss over time.

Lithium Plating

Lithium plating occurs when lithium metal builds up on the anode surface instead of intercalating into the anode material during charging. This happens more readily when the battery is kept at high voltage (fully charged) and low temperature. Lithium plating reduces cycling stability and poses safety risks like internal short circuits.

Factors That Affect Degradation Rate

Several factors influence the rate of degradation when a LiPo battery is left fully charged:

1. Temperature

Higher temperatures accelerate the chemical oxidation processes that damage the electrolyte and electrode materials. Storing batteries around room temperature (68–77°F or 20–25°C) is ideal for minimizing self-discharge.

2. State of Charge (SOC)

The higher the state of charge, the faster the degradation. Keeping batteries at 100% SOC (fully charged) causes the most rapid capacity loss over time.

3. Cell Chemistry

Some cathode chemistries like lithium cobalt oxide (LCO) are intrinsically less stable at higher voltages compared to lithium iron phosphate (LFP) and lithium nickel manganese cobalt oxide (NMC).

4. Age of Battery

Older batteries have already undergone more charge/discharge cycles and chemical degradation, so they will self-discharge faster than newer batteries.

5. Usage and Maintenance History

Poor maintenance practices like overcharging, over discharging, or exposing batteries to high temperatures accelerate capacity fading. Regular full charge/discharge cycles help “rejuvenate” batteries.

Best Practices for Storage

To minimize degradation during storage, here are some tips for properly maintaining your LiPo batteries:

• Avoid storing batteries fully charged. Experts recommend storing at around 3.85V per cell (30-50% SOC) for optimal longevity.
• Store batteries in a cool, dry place away from heat and moisture. Ideal storage temperature range is 40–70°F (4–21°C).
• Place batteries in fireproof containers like ammo cans or Lipo bags. Don’t stack loose batteries.
• Every 6 months, do a charge/discharge cycle to prevent capacity loss from self-discharge.
• If storing for >1 month, check voltage monthly and recharge to optimal storage voltage as needed.
• Before using after prolonged storage, do at least 2 charge/discharge cycles to “wake up” the battery and ensure normal function.

How Long Can a LiPo Battery Safely Stay Fully Charged?

There is no precise timeframe—the degradation processes begin as soon as a battery reaches full charge. Most experts recommend trying to avoid leaving a LiPo battery at 100% SOC for more than:

• 1-2 days at room temperature
• 3-4 weeks if stored refrigerated at 0 °C
• Up to 3 months maximum if stored frozen at -20 °C

Of course, these are general guidelines, and the true safe storage period depends on the specific battery and conditions. When in doubt, err on the side of caution and discharge batteries to storage voltage before extended storage time.

Regularly checking the open circuit voltage and doing occasional charge/discharge cycles helps detect issues before they become dangerous.

If catching voltage drops early, you can “rejuvenate” a battery that has self-discharged during prolonged storage. But capacity loss becomes permanent if the battery stays fully charged until it drops below safe operating voltage.

Signs of LiPo Battery Degradation

Watch for these warning signs that your LiPo batteries are losing capacity from being left fully charged:

• Reduced runtime/endurance on a full charge
• Lower open circuit resting voltage earlier into the discharge curve
• Longer charging times to reach full capacity
• Swelling or puffing up of battery case
• Increase in internal resistance (detectable with specialized equipment)
• Accelerated capacity loss over repeated charge cycles

What to Do With an Overcharged Puffed LiPo Battery

If a LiPo battery has swelled up from being left fully charged too long, stop using it immediately. A puffed battery case indicates gas buildup and increased internal pressure. This poses a safety risk of fire, explosion, or electrolyte leakage.

Follow these steps to safely handle puffed batteries:

• Place it in a fireproof Lipo bag or surplus ammo box outdoors.
• Avoid direct contact with the battery and do not try puncturing or disassembling it.
• Submerge the battery fully in salt water for 1-2 weeks to discharge it. The salt water neutralizes the electrolyte.
• Once fully discharged, the battery can be safely disposed of according to local hazardous waste regulations.
• Do not attempt to recharge or use a puffed LiPo battery again. The capacity loss and safety risks are too high at this point.

With proper storage and handling, LiPo batteries can maintain good performance for years. But leaving them fully charged for too long accelerates degradation and shortens their lifespan. Follow the recommendations in this article to maximize the longevity of your LiPo batteries.

Best Storage Practices for LiPo Batteries

To summarize, here are some best practices for storing LiPo batteries to avoid degradation from remaining fully charged:

• Discharge batteries to an optimal storage voltage of 3.85V per cell (about 40% charge level) before storage. This reduces strain on the battery chemistry.
• Store batteries in a cool, dry place around 40–70°F (4–21°C). Avoid temperature extremes. The cooler the better for slowing chemical reactions.
• Place each battery in its own fireproof container and avoid stacking batteries together. This contains any fire or leakage.
• Check the open circuit voltage monthly and recharge to optimal storage voltage as needed to account for self-discharge.
• Every 6 months, do a full charge-discharge cycle to keep the electrodes conditioned.
• Wipe off any condensation, infiltrated moisture or corrosion on terminals. This ensures good connections.
• Consider using dedicated storage chargers that automatically hold batteries at ideal voltages. This maintains optimal health with minimal monitoring.
• Don’t exceed the recommended maximum storage periods, even under good conditions. After 1-2 years, it’s advised to replace batteries if they won’t be used.
• Before reusing a stored battery, do 2-3 charge-discharge cycles to restore normal performance. The first few cycles may seem slow.
• Properly dispose of any puffed or damaged batteries that pose safety risks according to local hazardous waste regulations.

LiPo Battery Charging Best Practices

In addition to proper storage, adhering to good charging practices helps preserve your LiPo batteries:

• Avoid leaving batteries charging unattended whenever possible. Disconnect once fully charged.
• Don’t charge batteries inside hot vehicles or in direct sunlight. Heat accelerates aging.
• Use smart LiPo chargers with built-in protection circuits. They prevent overcharging/overheating.
• Select the right charge mode and rates for your particular battery type. Follow the manufacturer’s instructions.
• Monitor batteries for swelling/temperature rise during charging. Discontinue charging if this occurs.
• Charge in fireproof containers and on non-flammable surfaces. Exercise caution.
• Periodically re-calibrate chargers and test their functionality to ensure proper operation.
• Consider using voltage limit adapters as an extra layer of protection against over-charging.

Following prudent charging protocols in combination with the storage best practices outlined earlier will help keep your LiPo batteries performing optimally for years of service. Be mindful of the factors that accelerate aging, and take steps to mitigate those risks.

Warning Signs of an Unsafe LiPo Battery

Along with reduced performance, watch for these key indicators that a LiPo battery has become dangerously unstable and needs to be safely disposed of:

• Distinct swelling or puffing of the battery case. Even a small amount of puffing distorts the laminated electrode layers inside, compromising safety.
• Denting, cracking, leaking or corrosion of the battery enclosure. This allows moisture ingress and internal short circuits.
• Sharp drop in resting voltage over a short time, or voltage dropping below 3V per cell. This signals severe cathode dissolution.
• Abnormal increase in internal resistance or voltage drop under load. The battery loses power capability.
• Failure of the protection circuit or other electronics connected to the battery. The smart management systems are being damaged.
• Battery getting hot spontaneously without even being charged. Heat is a reaction of oxidizing battery materials.
• Strong, foul odors coming from the battery. This suggests electrolyte decomposition.
• Sparking, smoke or fire when charging or discharging the battery. The battery is hazardous.
• Difficulty charging the battery fully even at low currents, or rapid self-discharge. The electrodes have degraded badly.

Any of these conditions indicate irreversible damage has occurred. The battery should be quarantined and discharged fully before disposal to avoid safety incidents. Do not attempt to repair and reuse damaged LiPo batteries.

Disposal and Recycling of LiPo Batteries

LiPo batteries contain toxic and flammable materials, so they must be disposed of responsibly when no longer usable:

• Completely discharge dead batteries by submerging in salt water for 1-2 weeks before disposal. This neutralizes the hazardous electrolyte.
• Tape or wrap discharge wires to terminals to prevent short circuits during disposal.
• Take dead LiPo batteries to appropriate e-waste collection sites or recycling drop-off locations. Don’t throw them in normal trash.
• Some retailers offer trade-in programs to receive new batteries while recycling old ones.
• Damaged or puffed LiPo batteries may need to go to hazardous waste management facilities; check local guidelines.
• Never incinerate or puncture LiPo batteries—this poses serious fire, health and environmental hazards.
• Support proper recycling to recover valuable metals in LiPo batteries like lithium, cobalt, nickel and manganese.

Proper end-of-life management keeps these batteries out of landfills and waterways while replenishing metal supplies. Handled irresponsibly, they can leach toxic chemicals or ignite fires in waste systems. Carefully recycling dead batteries closes the loop on the LiPo lifecycle.

Frequently Asked Questions

How can I tell if my LiPo battery needs to be recharged after storage?

Check the open circuit voltage. If any cell is below 3.85V, the battery needs to be recharged to bring it back up to optimal storage voltage.

Can I leave batteries at a partial charge instead of fully charged?

Yes, storing LiPo batteries at a 40-50% charge level (3.85V per cell) is ideal to minimize strain and degradation over time.

What temperature should I avoid storing LiPo batteries at?

Avoid freezing temperatures below 0°C or excessive heat above 45°C. The ideal storage temperature range is about 4–21°C.

Is it safe to use a LiPo battery that has been in storage for over a year?

Most experts recommend replacing LiPo batteries after 1-2 years in storage. But with a few slow conditioning cycles, they may still accept a charge. Use caution and watch for signs of failure.

Can damaged LiPo batteries be repaired at all?

No, once a LiPo battery shows clear signs of damage like puffing or swelling, it is unsafe and unwise to attempt repair. The best practice is to safely dispose of damaged batteries.

Conclusion

LiPo batteries require proper care—especially when storing them fully charged. Allowing batteries to sit at maximum voltage for extended periods accelerates chemical degradation and risks dangerous malfunctions.

By maintaining optimal storage voltage, conditions, and periodic maintenance, you can keep your LiPo batteries operating safely at peak performance for many years. But you must also diligently watch for signs of damage and irreversible failure. With this knowledge, you can get the most lifespan and effectiveness out of these powerful lithium polymer batteries.