Some people use their LiFePO4 batteries seasonally, such as camping in the summer or ice fishing in the winter.
It is common for some people to store lithium batteries during the off-season.
When storing LiFePO4 batteries, it is essential to keep them properly so they do not get damaged and can provide their peak performance for many years.
How To Store LiFePO4 Batteries?
How do I store my 12v lithium ion battery? This is a question our customers ask us daily, especially during the winter season.
The answer depends on the temperature you keep the batteries at and the length of time. Here is a summary of how to keep your LiFePO4 battery:
Recommended storage temperature: 0°C to +35°C
Storage up to 1 month: -20°C to +60°C
Hold up to 3 months: -10°C to +35°C
Extended storage time: +15°C to +35°C
It is highly recommended to store lithium batteries indoors during the off-season.
Keeping LiFePO4 batteries with a state of charge of about 60% (SOC) or higher is also recommended.
If batteries are stored for a more extended period, change the batteries cyclically at least every three months. Do not store discharged batteries.
Disconnect LIFEPO4 Before Saving
Many customers have master switches to disconnect the battery from the power supply. We recommend you take the extra step to ensure the batteries are disconnected.
This is because many RVs still have components running in the background, such as B. the C02 sensor, the backlight of the stereo, or another emergency sensor that bypasses the main circuit breaker.
The best thing you can do when storing the batteries is to physically separate the main positive and negative wires from the lithium batteries.
This ensures that the battery is not discharged during storage and that the LiFePO4 batteries are sufficiently charged when used again.
Always use a lithium battery maintainer instead of one designed for other battery chemistries.
LiFePO4 batteries have a low self-discharge of 2% per month. This means a lithium battery loses 2% of its charge capacity monthly when stored.
We recommend disconnecting all current draws from your batteries to avoid a higher discharge rate.
When storing LiFePO4 batteries, you must keep them with a state of charge (SOC) of 60% or higher.
A higher form of control is recommended for more extended storage. If you want the battery to remain well charged after the storage period has expired, you should set it to 100% and store it in this fully charged state.
How To Store LIFEPO4 With The System?
Suppose you store your LiFePO4 batteries with your entire solar panels system, like your charger and inverter.
In that case, we recommend using a battery monitor that protects LiFePO4 batteries by disconnecting them from parasitic loads when the voltage reaches 11.5V.
If no circuit breaker is installed, removing the main battery connectors is recommended.
Disconnecting the charger while storing the batteries is okay, as LiFePO4 batteries do not require trickle charging.
How To Store LIFEPO4 In Cold Weather?
Lithium cells are not affected by temperature extremes when the battery is not in use.
We do not recommend storing RV batteries in frigid temperatures for long periods, as this may cause the cell shell inside the battery to crack.
In addition, hot temperatures above 60°C can damage other components in the battery pack, so it is best to avoid high temperatures for long periods.
It is always recommended to store lithium batteries indoors and at room temperature.
The Danger Of Not Charging Before Battery Storage
Storing your LiFePO4 battery without a charge will have serious consequences. Due to the self-discharge rate of 2%, the battery can become deeply discharged.
The discharge level may drop below what the BMS can protect. Because of this, it is essential to charge your lithium battery before storing it.
It is highly recommended to keep the lithium battery at room temperature, especially if it is also reserved for an extended period.
Check the first paragraph of this article for how long you can store LiFePO4 in different temperature ranges.
Deep discharging the cells from storage without a charge can cause permanent damage and void your 2-year battery warranty.
Cold Weather Performance
There is a potential loss of capacity when discharging LiFePO4 batteries in frigid temperatures (below 0 degrees Celsius).
For example, in sub-zero temperatures, a 12V 120Ah LiFePO4 battery may only deliver 100Ah, 90Ah, or even 70Ah, depending on how cold it is.
This is natural to LiFePO4 chemistry and only temporary. Total capacity is restored when the battery warms up again.
At 0°C, a VB007 battery (12V 120Ah) delivers about 100-ampere hours. At -20 °C, the battery’s capacity drops to around 70 ampere hours.
Charging LiFePO4 batteries in sub-zero temperatures can cause lithium plating, a dangerous phenomenon that can lead to short circuits.
That’s why all Creabest LiFePO4 batteries have a built-in BMS that protects against charging in cold weather. The BMS is also responsible for protecting against other factors, including:
- High-temperature charging
- Overload
- Deep discharge
- Internal shorts
Can You Connect LiFePO4 Batteries In Parallel?
Related knowledge of LiFePO4 batteries in parallel
First, we need to know that when two or more LiFePO4 batteries are connected in parallel, the current flowing through each battery cannot be the same.
For example, let’s say you use two 12.8V 100Ah batteries in parallel. If the battery system is connected to a 50A load, each battery’s burden may be slightly different than 25A.
One battery can be loaded with 21A, while the other is loaded with 29A. This current difference becomes more noticeable when the load is more extensive.
Also, as the number of batteries connected in parallel increases, it becomes increasingly difficult to obtain power from each battery and direct it equally to each battery.
To complicate matters further, each battery has a unique internal resistance and therefore sinks/generates a current at slightly different rates.
Causes Of The Current Imbalance In LiFePO4 Batteries After Parallel Connection
Differences in the manufacturing process of cells and batteries, battery connection resistance, and temperature differences between batteries and other field installation variables cause the current imbalance between batteries.
Even if the batteries are manufactured in the same batch, their resistance and power supply capacity can differ.
And the different currencies in each parallel branch cause the battery state of charge (SOC) to diverge.
The battery with the best performance will be discharged faster than the others.
Then the SOC of all batteries converges again, as the fastest depleting battery reaches a point where it can no longer supply as much power to the system.
At this point, the stronger storms will be the ones that initially delivered less energy but now have a higher SOC.
The conclusion is that for most of the battery system’s life, there will be a difference in SOC between each LiFePO4 battery connected in parallel.
The SOC difference between the batteries means that even when the load is off, eddy currents will flow between the batteries as they have to equalize the SOC status of the battery system connected in parallel.
Sometimes eddy currents between batteries can be abnormally high, causing the cells to go into an unpredictable protection mode.
It is important to note that the discharge curve of a LiFePO4 battery is very flat, so it can take many hours for the batteries’ SOC level to equalize once a load is removed.
It’s possible that the batteries won’t balance no matter how long you wait due to diffusion voltages or what some call “surface charge.”
Of course, a battery management system (BMS) can deal with the parallel branch current unbalanced and uncontrolled eddy current, but it cannot 100% solve this problem.
It can only achieve a relatively balanced state between the paralleled batteries. The battery life can be reduced as soon as the wind in the parallel branch is higher than expected.