Can I Use an Alternator Regulator to Charge Lithium (LFP) Batteries?
Is It safe to charge my lithium iron phosphate (LiFePO4) batteries with an alternator/voltage regulator?
LiFePO4 batteries are a type of Lithium iron phosphate batteries also known as Li-ion batteries. Lithium iron phosphate (LiFePO4) batteries are becoming increasingly popular for use in boats, RVs, and vans and you can will how to charge these batteries with an alternator regulator in this article.
LiFePO4 batteries a number of advantages over traditional lead-acid batteries, including longer lifespan, lighter weight, faster charging times and larger percentage capacity (lead is about 50% available while LiFePO4 is about 80% of what battery amp hours rating is). ARCO has recognized this trend and developed the Zeus High Energy Alternator Regulator, which is designed to safely charge lithium batteries as well as all other battery chemistries. This alternator regulator will help you protect your investment in your energy system and ensure that your lithium batteries last for years to come.
Before you learn how alternator regulators are safe for lithium batteries, it is best that you are equipped with the knowledge of what an alternator regulator does.
What is an Alternator Regulator?
Definition: An alternator regulator is a device that controls the output voltage of an alternator. It is responsible for ensuring that the output of the alternator is always within a safe range, regardless of the load on the alternator.
Purpose: The purpose of an alternator regulator is to protect the battery and other electrical components in a vehicle. If the alternator output voltage is too high, it can damage the battery and other components. If the alternator output voltage is too low, it can cause the battery to not charge properly. More advanced alternator regulators provide additional purposes such as regulating temperature and amperage on the battery and alternator and controlling the field of the alternator to power the takeoff of the engine.
What are the safety considerations for Lithium Batteries?
Risk of Overcharging
Loss of capacity: Over discharging a Li-ion battery can damage the electrodes and electrolyte, which can lead to a loss of capacity. This means that the battery will not be able to store as much energy, and its lifespan will be shortened.
Polarity Reversal: If the cells get discharged too far, a polarity reversal can happen. If this occurs, the bank is now damaged.
Increased impedance: Over discharging a Li-ion battery can also increase its impedance, which is the resistance to the flow of current. This can lead to slower charging and discharging times, and it can also make the battery more susceptible to damage and overheated wires.
To avoid the risks of over-discharging an (LFP)battery, it is important to follow the manufacturer's instructions. In general, it is best to not discharge the battery below its lower voltage limit. This limit is typically specified in the battery's datasheet.
Here are some tips for preventing over-discharging an Li-ion (LFP)battery:
Use a battery monitor that has an alert setting to prevent the battery from being discharged below its safe limit. Battery management systems (BMS) also work to monitor and protect your battery from being overly-discharged. Most LifePo4 batteries feature an internal BMS.
- Monitor the battery's voltage regularly. If the voltage drops below the lower voltage limit, stop using the battery and recharge it.
Do not leave the battery in a discharged state for an extended period of time. This can damage the battery and shorten its lifespan. When a LiFePO4 battery is discharged, the lithium ions in the battery move from the positive electrode to the negative electrode. This leaves behind lithium phosphate crystals on the positive electrode. If the battery is left in a discharged state for too long, these crystals can grow and become hard. This is called sulfation. Sulfation can make it difficult for the battery to recharge and can eventually lead to the battery's death.
Risk of Over Heating
There are a number of factors that can cause a LiFePO4 battery in a vehicle to overheat, including:
Physical damage: If a LiFePO4 battery in a vehicle is dropped or otherwise damaged, the internal components of the battery can be damaged, which can lead to a short circuit.
Extreme temperatures: LiFePO4 batteries in vehicles should not be charged in extreme temperatures, such as very hot or very cold temperatures. Extreme temperatures when charging LifePO4 batteries are below 32°F (0°C) and above 140°F (60°C).
Faulty battery management system: The battery management system (BMS) is responsible for monitoring the battery and preventing it from overheating. If the BMS is faulty, it can fail to prevent the battery from overheating. As mentioned earlier, LiFePO4 batteries feature an internal BMS.
If a LiFePO4 battery in a vehicle/boat does overheat, it can shorten the lifespan of the battery. Here are some tips for preventing LiFePO4 battery overheating in vehicles:
Use the correct charger: Make sure you are using the correct charger for your vehicle/boat. Using a different charger can cause the battery to overheat. One thing to look for in a charger is that it should also have a current output that is less than or equal to the battery's capacity. For example, a 100 Ah battery should be charged with a charger that has a current output of 10 amps or less.
Avoid overcharging: Do not leave your vehicle/boat plugged in for extended periods of time. Once the battery is fully charged, unplug it. When un-used, in general, a LiFePo4 battery will discharge at a rate of about 2% per month at 25 degrees Celsius (77 degrees Fahrenheit). This means that a 100 amp-hour (Ah) battery will discharge by 2 amp-hours (Ah) per month. To maintain batteries that are not in use, a trickle charger is a type of battery charger that provides a small, constant current to a battery to keep it topped off.
- Do not damage the battery: Be careful not to drop or otherwise damage your LFP battery.
Store the battery in a cool, dry place: Storage temperatures can range anywhere from -5 to +35°C (23 to 95°F).
- Have your vehicle/boat regularly serviced: A qualified technician can inspect your vehicle/boat battery and BMS for any problems.
How can you safely charge your lithium batteries?
High Energy Alternator regulators are safe to charge lithium iron phosphate (LiFePO4) batteries because they are specifically designed for LFP batteries through multiple voltage settings, limiters that can prevent the battery from being over drawn, temperature sensing to adjust the charging voltage depending on the temperature of the battery to name a few. Standard alternator regulators are not designed for LiFePO4 batteries and can overcharge them, which can damage the batteries.
LiFePO4 batteries have a different charging voltage than lead-acid batteries. Lead-acid batteries typically need to be charged to a voltage of 14.2 to 15.0 volts, while LiFePO4 batteries only need to be charged to a voltage of 13.6 to 14.6 volts (brand dependent). If an alternator regulator is not designed for LiFePO4 batteries, it may continue to charge the batteries at a higher voltage, which can damage them.
In addition, LiFePO4 batteries have a different charging profile than lead-acid batteries. LiFePO4 batteries need to be charged at the specified charge current, voltage, as well as constant voltage duration. Standard alternator regulators typically won’t be able to provide the correct charge profile for LiFePO4 batteries. Lacking correct charging can also damage them.
Here are some additional tips for safely charging LiFePO4 batteries with an alternator regulator:
Use a high-quality alternator regulator that is specifically designed for Li-ion batteries.
Set the charging voltage, and recommended current, to the voltage provided on your battery’s label.
Monitor the batteries closely during charging.
Use an alternator load dump protection device. When a load dump event occurs, the voltage on the battery bus can rise sharply, sometimes up to 120 volts or more. This can damage the alternator's diodes, the voltage regulator, and other electrical components. The alternator load dump protection device helps to prevent this damage by clamping the voltage on the battery bus to a safe level.
By following these tips, you can safely charge your LiFePO4 batteries with an alternator regulator and extend their lifespan.
In conclusion, Standard alternator regulators are not designed for LiFePO4 batteries and can overcharge them, which can damage the batteries. High energy alternator regulators are safe to charge lithium iron phosphate (LiFePO4) batteries because they are specifically designed for LFP batteries. They have multiple voltage settings, limiters that can prevent the battery from being over drawn, temperature sensing to adjust the charging voltage depending on the temperature of the battery, and other features that make them safe for charging LiFePO4 batteries.