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How to Wake Up a Sleeping LiFePO4 Battery

Power - by Joe Weber - updated on 8/9/2023

Using a multimeter to check on a battery

A sleeping LiFePO4 battery is different from your normally fully discharged battery, as it has reached a voltage level that requires special attention to bring it back to its normal operating condition safely. The voltage level is not the only reason for this to happen but it is one of the key reasons. Keep reading to learn what to do if your battery won't provide power to your device or accept a charge from your charger.

Did You Know That This Could Happen?

If you are new to using lithium iron batteries, you may not even know that sleep mode or protection mode is even a thing. Both of these modes are part of the battery management system (BMS) built into the battery to help manage and improve the performance and safety of the battery. The simplest way to describe what a BMS does is when certain conditions are met, the battery is essentially disconnected until it is safe to operate again.

Is Protection Mode the Same as Sleep Mode?

Protection mode on a LiFePO4 (Lithium Iron Phosphate) battery refers to a safety feature that is built into the battery management system (BMS) to prevent potential damage or hazardous situations. When a LiFePO4 battery enters protection mode, it typically means that certain conditions or parameters have been exceeded.

  • Overcharge: If the battery voltage surpasses a predefined upper limit, the BMS will activate protection mode.
  • Undervoltage: When the battery voltage drops below a predetermined lower limit, the BMS will activate protection mode.
  • Overcurrent: If the battery experiences a sudden surge in current that exceeds safe limits, the BMS will enter protection mode.
  • Overtemperature: When the battery temperature rises beyond a specified threshold, the BMS will initiate protection mode.

Important Note

Not all lithium batteries have a full BMS and the triggers could differ depending on the brand and application of the battery. Protection mode can be triggered due to any of these reasons, and sleep mode acts as an extension of protection mode.

Why Does A LiFePO4 Battery Go Into Sleep Mode?

When a battery management system (BMS) enters sleep mode, it typically occurs when the cell groups of the battery fall significantly below the Low Voltage Cutoff (LVC) threshold. This situation commonly arises when the battery is stored and remains unused for an extended duration.

How Do I Get My Battery Out of Sleep Mode?

There are several ways to wake up a sleeping LiFePO4 battery. From connecting the battery to a charge from a solar panel, to warming up the battery and even connecting your sleeping battery in parallel to another LiFePO4 battery. The steps below are the safer and easier way to wake a sleeping lithium battery.

  • Check the battery voltage:
    Use a battery voltage tester or a multimeter to measure the voltage of your battery. If the voltage is below a certain threshold (usually around 2.5 to 2.8 volts per cell), the battery might be in a deep discharge state.
  • Apply a low current charge:
    Connect the battery to a LiFePO4-compatible charger that supports low-current charging. Make sure you use a charger designed for LiFePO4 batteries to prevent any damage or overcharging.
  • Verify correct charging voltage:
    The charger must have the appropriate voltage for your LiFePO4 battery. The charger's voltage must be above 3.25 volts per cell. A charge of 3.65 volts per cell with a current limited to C/10 (or less) is recommended to release the battery from "sleep".
  • Monitor the charging process:
    Leave the battery connected to the charger and allow the battery to charge slowly while monitoring the voltage closely. The charger should gradually bring the voltage up to a safe level. It's important not to rush the process to avoid damaging the battery.
  • Check for signs of recovery:
    Check the battery voltage after a while to see if it has increased to an acceptable level (usually around 3.2 to 3.3 volts per cell). If the voltage has increased, it indicates that the battery is starting to wake up and it will begin to accept a normal charge.
  • Resume normal charging:
    After the battery voltage has reached a suitable level, you can switch to a regular LiFePO4 charger or continue using the same low-current charger to fully charge the battery. Follow the manufacturer's guidelines for the ideal charging current and voltage.

How Do I Prevent This From Happening in the Future?

Properly maintaining your battery is the best thing you can do to prevent unnecessary issues from throwing a wrench in your plans when your batteries aren't used in a while.

Fully Charge them after each use

Every time you use your lithium batteries you should recharge them up to a full charge, even when you've only used a small amount of energy.

Store them at room temperature

When your batteries are not being used they should be stored in a dry, room-temperature place, like a garage.

Store them fully charged

Before storing them for longer periods, charge your lithium batteries completely. You should always store your lithium batteries with a full charge.

Charge them regularly

While in storage, charge them at least once every six months. Even when storing batteries at full charge, they will discharge slightly over time. Keep them healthy by keeping them at a full charge as much as possible.

If I Regularly Charge Them In Storage, Won't That Shorten Their Life?

No! Many Lithium Iron Phosphate batteries, like our new X2Power Lithium Bluetooth line, feature a long 10-year/2,000 cycle warranty. As long as you don't let the batteries discharge all the way before you recharge, your batteries will stay in excellent health.

If your batteries are acting strange or you are concerned about your battery's health, bring them to your local Batteries Plus to have our battery experts test them and help you bring them back to life.

While you're here, don't forget to take a look at our X2Power chargers which are designed to work with your new lithium iron phosphate batteries to keep them charged and healthy throughout their entire life.

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