Charging Lithium Iron Phosphate Batteries (LiFePO4)
How to charge a LiFePO4 batteries? That is one of the most common questions we get from our customers. The answer is simple: use a LiFePO4 battery charger, of course. When charging LiFePO4 batteries, make sure that you are not using a charger meant for other lithium ion chemistries, which are typically designed with a higher voltage than what is required by LiFePO4. We are often asked if a lead-acid battery charger can be used to charge lithium iron phosphate. The short answer is yes, as long as the voltage settings are within the acceptable parameters of LiFePO4 batteries.
Before using a LiFePO4 charger, check that your charger’s cables are insulated and free of breakage. Charger terminal connectors should be clean and properly mate with the battery terminals to ensure a good connection and optimum conductivity. Please refer to Canbat’s user manual, or your specific battery’s datasheet, for appropriate torque settings.
If LiFePO4 batteries are not fully discharged, they do not need to be charged after each use. LiFePO4 batteries do not get damaged when left in a partial state of charge (PSOC). You can charge your LiFePO4 batteries after each use or when they have been discharged up to 80% DOD (20% SOC). If the Battery Management System BMS) disconnects the battery due to low voltage (voltage will be <10V), remove the load and charge immediately using a LiFePO4 battery charger.
LiFePO4 batteries can be safely charged between 0°C to 45°C (32°F to 113°F). LiFePO4 batteries do not require temperature compensation for voltage when charging at hot or cold temperatures. All Canbat LiFePO4 batteries come with an internal BMS that protects the battery from low and high temperatures. If the BMS disconnects due to low temperature, the battery must warm up for the BMS to reconnect and accept the charging current. If the BMS disconnects because of high temperature, the battery will need to cool down before the BMS will accept charging the battery. Please refer to your specific battery’s datasheet for the BMS low temperature and high-temperature cut-off and reconnect values.
The charging and discharging temperature for lithium batteries from our LT series is -20°C to 60°C. Canbat Low Temperature (LT) Lithium Batteries are cold-weather rated, designed for Canada’s cold climates. These batteries have a built-in heating system featuring proprietary technology that draws power from the charger. No additional components are required. The entire process of heating and charging is completely seamless. The heating system automatically activates once charging below 0°C is attempted, and it automatically deactivates when it’s no longer needed. The heating system does not take power from the battery, but rather from the charger, ensuring the lithium battery is not discharging itself and keeping you powered. Simply plug the LT lithium battery into the LiFePO4 charger and the internal heating and monitoring systems take care of the rest.
How to charge LiFePO4 batteries with a lead-acid charger
Most lead-acid battery chargers can be used with LiFePO4 batteries as long as they are within the appropriate voltage guidelines. AGM and Gel algorithms typically fall within the LiFePO4 voltage requirements. The voltage for flooded battery charging algorithms is often higher than LiFePO4 charging requirements, which will result in the BMS disconnecting. If this happens, it is generally good practice to replace your charger for one with a LiFePO4 charge profile. Since the BMS protects the battery, using lead-acid chargers will typically not damage the battery.
Note that if the BMS disconnects due to low voltage, a lead-acid battery charger may not be able to reconnect the BMS, even if the charger has the acceptable charging parameters to charge LiFePO4. This is because when the BMS disconnects, the lithium battery will not have a voltage as it will read 0V on a voltmeter, while lead-acid chargers require the battery to read out a voltage to start charging. If the battery is reading 0V, the lead-acid battery charger will not be able to understand that a battery is connected and that it should start charging. This is also true for some low-quality lithium chargers. It is always recommended that you invest in a high-quality LiFePO4 charger to ensure high performance and longevity. Feel free to contact Canbat should you have any questions.
Charging LiFePO4 in Parallel
When connecting LiFePO4 batteries in parallel, please make sure each battery is within 0.1V of each other before putting them in service, This will minimize the chance of imbalance between batteries. If you’re charging 12V LiFePO4 batteries, the charging voltage should be between 14V – 14.2V. When charging 24V batteries in parallel, the charging voltage should be 28V – 28.4V. Charging 36V lithium batteries in parallel requires a voltage of 42V – 42.6V. Finally, charging 48V LiFePO4 batteries require voltage parameters of 56V – 56.8V. Below is a table with a summary showing the voltage requirements for each system voltage.
|System Voltage||Charging parameters|
|12V||14V – 14.2V|
|24V||28V – 28.4V|
|36V||42V – 42.6V|
|48V||56V – 56.8V|
The voltage parameters apply to both charging profiles CC and CC-CV. If your charger’s voltage is lower than those listed in the table, it will not damage your battery, but it will be undercharged, and it will not provide the full rated capacity of the battery. If your charger’s voltages are higher than those listed in the tables above, the BMS may disconnect the battery and you may have to remove the load to reconnect. We recommend you replace the charger to avoid this inconvenience and to invest in a high-quality LiFePO4 battery charger.
Charging LiFePO4 batteries in Series
When connecting batteries in series, please make sure each battery is within 50mV (0.05V) of each other before putting them in service. This will minimize the chance of an imbalance between batteries. If your batteries get out of balance, the voltage of any battery is >50mV (0.05V) from another battery in the set, you should charge each battery individually to rebalance. You can charge each battery individually periodically to avoid imbalance. When charging LiFePO4 batteries in series, it is best to use a multi-bank charger that charges each battery individually to ensure the cells remain balanced. You can also use a 24V battery LiFePO4 charger or a 48V battery LiFePO4 charger if you’d like to charge your system as a whole.
Charging LiFePO4 with an Inverter/Charger and/or Charge Controller
Below are the key, typical charger inputs when using an inverter/charger or charge controller for charging LiFePO4 batteries. Many inverter/ chargers require additional parameters, please contact Canbat technical support for assistance. LiFePO4 batteries do not require equalizing. LiFePO4 batteries do not require temperature compensation for voltage when charging at hot or cold temperatures.
|PARAMETER||12V SYSTEM||24V SYSTEM||48V SYSTEM|
|Bulk Voltage||14V – 14.6V||28V – 29.2V||56V – 58.4V|
|Absorption Voltage||14V – 14.6V||28V – 29.2V||56V – 58.4V|
|Absorption Time||0- 6 min||0- 6 min||0- 6 min|
|Float Voltage||13.8V ± 0.2V||27.6V ± 0.2V||55.2V ± 0.2V|
|Low Voltage Cutoff||10V||20V||40V|
|High Voltage Cutoff||14.6||29.2V||58.4V|
Charging LiFePO4 with alternator and DC to DC Chargers
Depending on the quality of the alternator, it may work fine to charge LiFePO4 batteries without modifications. However, low-quality alternators with poor voltage regulation can cause the BMS to disconnect LiFePO4 batteries. If the BMS disconnects the batteries the alternator may be damaged. To protect your LiFePO4 battery and alternator, please be sure to use a compatible high-quality alternator or install a voltage regulator. You can also use a DC to DC charger to safely and effectively charge your batteries including house banks. Installing a DC to DC charger is the recommended option when it comes to charging lithium with an alternator.
Fuel Gauges for Lithium batteries
If you are using a voltage-based fuel gauge that is designed for lead-acid batteries, it will not accurately measure the state of charge (SOC) of LiFePO4 batteries. Please replace your fuel gauge with one that measures current rather than voltage to accurately measure the state of charge of lithium iron phosphate batteries.
If you have any technical questions, please contact Canbat Technical Support at +1 778-358-3925.
Frequently Asked Questions (FAQ)
Can I charge lithium with solar panels?
Yes, you can charge Canbat lithium batteries with solar panels. In fact, you can charge them with any type of charging equipment, as long as the charging voltage is within 14V to 14.6V for our 12V LiFePO4 batteries.
Can I charge lithium with an alternator?
Yes, but it is recommended to invest in a DC to DC charger to protect your LiFePO4 battery and alternator.
Can I charge lithium with a lead-acid charger?
Most lead-acid battery chargers can be used with LiFePO4 batteries as long as they are within the appropriate voltage guidelines. AGM and Gel algorithms typically fall within the LiFePO4 voltage requirements. The voltage for wet cell or flooded battery charging algorithms are often higher than LiFePO4 requirements, which will result in the BMS disconnecting the battery at the end of the charge cycle, and may result in the charger displaying an error code. If this happens, it is generally good practice to replace your charger. Since the BMS protects the battery, using lead-acid chargers will not damage the battery.
How to charge a LiFePO4 battery in the cold?
LiFePO4 batteries can safely charge between 0°C to 45°C (32°F to 113°F). If your application requires you to recharge in freezing temperatures, Canbat Low Temperature series (LT) can be recharged between -20°C to 45°C (-4°F to 113°F). The LT series has a built-in heating system featuring proprietary technology that draws power from the charger itself. No additional components are required. The entire process of heating and charging is completely seamless. The heating system automatically activates once charging below 0°C is attempted, and it automatically deactivates when it’s no longer needed. The heating system does not take power from the battery, but rather from the charger, ensuring the battery is not discharging itself. Simply plug the battery into the lithium charger and the internal heating and monitoring systems take care of the rest.
Do I need a special charger for lithium?
The short answer is no. In order to fully charge a 12V LiFePO4 battery, a charger with a voltage of 14V to 14.6V is required. Most AGM battery chargers are within that range and they would be compatible with Canbat lithium batteries. If you have a charger with a lower voltage, it may still charge the battery, but it won’t charge it to 100%. A charger with a higher voltage would not charge the battery and the BMS would enter protection mode due to its high voltage disconnect feature. Although many AGM battery chargers are compatible with LiFePO4, wet cell or flooded battery chargers are not compatible as they typically charge at a higher voltage.
Can I fully discharge a lithium battery?
Canbat LiFePO4 batteries can be discharged up to 100% of their capacity. However, to optimize the performance of your LiFePO4 battery, to achieve a higher cycle life, and to avoid the BMS disconnecting the battery, we recommend limiting the discharge to 80%. If the BMS disconnects the battery due to low voltage, at 100% depth of discharge, remove the load and recharge using a LiFePO4 charger to reactivate the BMS.
Can lithium discharge in cold temperatures?
LiFePO4 batteries can safely discharge between -4°F to 140°F (-20°C to 60°C). All Canbat LiFePO4 batteries come with a built-in BMS that protects the battery from low-temperatures and high-temperatures. If the BMS disconnects due to cold or high temperature, wait until the temperature is more suitable and the BMS will reconnect automatically.
How do I store lithium batteries?
It is recommended to store LiFePO4 batteries at about 50% state of charge (SOC). If the batteries are stored for long periods of time, cycle the batteries at least every 6 months. Do not store batteries that are discharged. They do not require a trickle charger. · Recommended storage temperature: -5 to +35°C (23 to 95 °F) · Storage up to 1 month: -20 to +60°C (4 to 140 °F) · Storage up to 3 months: -10 to +35°C (14 to 95 °F) · Extended storage time: +15 to +35°C (59 to 95 °F) It is highly recommended to store lithium batteries indoors during the offseason.
Can I connect 12V lithium in series?
Yes, you can connect up to four 12V batteries of the same model in series to obtain a higher voltage. Do not connect lithium batteries in both parallel and series simultaneously. Please note that the 24V lithium batteries are designed for 24V applications and do not support series connections. Likewise with the 36V and 48V lithium batteries. When charging LiFePO4 batteries in series, it’s recommended to use a multi-bank battery charger that can charge each battery individually. If that’s not an option, you can also use a 24V battery LiFePO4 charger or a 48V battery LiFePO4 charger if you’d like to charge your system as a whole. Canbat lithium batteries support charging in series.
Can I connect 12V lithium in parallel?
Yes, you can connect up to four 12V batteries of the same model in parallel to obtain a higher capacity. Do not connect lithium batteries in both parallel and series simultaneously. Canbat 24V and 36V lithium batteries also support up to 4 units in parallel. Canbat 48V LiFePO4 batteries support up to 14 units in parallel as they are designed for larger projects. Canbat lithium batteries support charging in parallel.
Can I install a lithium battery on its side?
Yes, Canbat LiFePO4 batteries can be installed upright or on their sides. Please fasten the battery if installed in a moving vehicle, such as in an RV or a boat. Please also avoid placing anything over the battery, and it’s recommended to cover the terminals with a plastic cap to prevent an external short circuit.
Are LiFePO4 batteries safe?
Yes, LiFePO4 is a safe chemistry and the most stable lithium-type battery on the market. Canbat lithium is UL 1642 certified, which means they have been tested for short-circuit, abnormal charging, crush, impact, shock, vibration, heating, temperature cycling and pressure. All Canbat LiFePO4 batteries come with an internal Battery Management System. The BMS protects against
- Under-Voltage – during discharge
- Over-Voltage – during charge or regen conditions
- Over-Current – during discharge
- Low-Temperature – during charge and discharge
- High-temperature – during charge and discharge
- Short-Circuit Protection – protects battery cells from damage
- Single Cell Equalization and balancing
If you already have a lead-acid or a LiFePO4 charger and you want to make sure it’s compatible, chat with one of our battery experts. We can check your charger’s user manual and confirm the voltage parameters. Canbat offers Canada-based 24/7 chat support to all its clients.