In the period from 2012-2021, we spent a lot of time talking about AGM batteries: what they are, what makes them different from traditional flooded acid lead acid batteries, and what shops and vehicle owners/consumers need to know when it comes to servicing them. While the knowledge transfer on AGMs is still ongoing, there are new battery chemistries making their way into the North American market, both as OE-installed batteries and as aftermarket replacements. A critical newer battery type is the LiFePO4 (or LFP) Lithium battery type.
We received an email from Interstate Batteries this week, touting their lineup of LiFePO4 batteries and it caused us to think that our readers are probably seeing a lot about these battery types but may not yet have a great handle on what they’re all about. So, this month, we thought we would address this newish battery type in a similar way that we have with AGM batteries in the past.
Tackling the alphabet soup of lithium types
The reality of lithium batteries is that they are a relatively new technology and, as such, there are many different lithium battery types competing for commercial success and dominance. This is somewhat problematic when it comes to servicing these different battery types, since all lithium batteries don’t have the same voltage. This means that different lithium batteries require different charging energy. To make matters worse, as we’ll see below, lithium batteries are very sensitive to over-voltage conditions, which can often result in bad outcomes.
It is really important to emphasize that there are many different lithium battery types out there, which we refer to as different lithium chemistries. These include nickel manganese cobalt (NCM), lithium cobalt oxide (LiCoO2) and many other types, including LiFePO4/LFP. Also, along with the different chemistries, there are different configurations in terms of cell structure, leading us to our common warning, “All lithium batteries are not created equal.” It is critical to make sure that any charger you are using to charge any lithium battery, even a LiFePO4 battery, is properly mated to the specific lithium battery that you are servicing. Lithium batteries are sensitive to voltage and can be dangerous if exposed to excessive voltage. So, check before you service your lithium battery–know the type of lithium battery it is and that your equipment is compatible with it.
What is the LiFePO4 battery and why has it become so popular?
For the purposes of the article, we are specifically addressing the needs and service issues of lithium iron phosphate batteries, which are often referred to as LiFePO4 or LFP batteries. LiFePO4 batteries are a type of “lithium-ion” battery known for their stability as compared to other lithium battery types, including other lithium-ion batteries. This stability means that they can be used in a wide variety of applications with a high degree of relative safety. They also have a longer cycle life than other lithium battery types and a much longer cycle life vs. lead acid batteries. Additionally, they do not contain heavy metals, such as cobalt, which reduces their toxicity levels when compared to other lithium battery chemistries. This is why they have been so widely adopted for vehicle and other transport applications. They also have some downsides, including lower energy density than other lithium chemistries. But, for now, they offer the best combination of safety and performance from an OE perspective, as evidenced by their overwhelming dominance in vehicle and transportation applications.
These batteries are used in a variety of passenger vehicle applications, typically in more advanced vehicles. For instance, BMW M-Series vehicles since 2016 have used a LiFePO4 battery as the primary vehicle starting battery. Tesla Model S and X vehicles adopted the LiFePO4 battery as the low-voltage battery in mid-year 2021. Similarly, thanks to their light weight and long cycle life, these batteries have become popular in many RV, powersports, motorcycle, and marine applications.
What do I need to know to service LiFePO4 batteries?
First, let’s cover the good news. If you are addressing a vehicle or piece of equipment requiring a jump-start, you can use any voltage-compatible jump starter. By voltage-compatible, we mean, if it’s installed into a 12V system, use a 12V jump starter, if it’s installed in a 24V system, use a 24V jump starter, etc. Once you have confirmed that you have properly matched the battery/system voltage, you can use any type of jump starter, whether it’s powered by a traditional AGM battery, a lithium battery or an ultracapacitor power source. When you’re jump-starting, you are making a DC-DC connection and simply augmenting the disabled battery. Since everything is in the correct voltage window, no harm will come from using a lead acid jump starter on a system with a lithium starting battery and vice versa.
Unfortunately, the same can’t be said for charging. The difference here is that a charger delivers energy to a battery and LiFePO4 batteries require their energy delivery in a specific manner. The charging requirements for a LiFePO4 battery are different from those of other lithium batteries and also different from those of lead-acid batteries. It’s similar to how we’re always saying that you shouldn’t charge an AGM battery with a charger designed to charge flooded acid batteries. In both cases, it’s all about voltage. In the case of LiFePO4 batteries, they have a fully charged voltage per cell that should never be exceeded. Doing so could result in LiFePO4 battery deterioration (at best) or complete battery destruction (at worst).
So, the key is to always, every time, charge your LiFePO4 batteries with a battery charger specifically designed to charge and maintain LiFePO4 lithium batteries. As noted above, a quality LiFePO4-specific charger is going to precisely control its voltage output. It is also going to deliver the specific charging routine required by LiFePO4 batteries. Finally, it is going to protect the battery from unsafe charging conditions, as noted below.
LiFePO4 charging: Things to watch for
Proper BMS management
A quality charger will play nice with the BMS (battery management system) used in these batteries. The BMS is like the battery’s brain. It monitors the battery and protects it from unsafe conditions.
2-stage charging: Constant current followed by constant voltage
When we referred to delivering the specific charging routine required by LiFePO4 batteries, this is what we mean. This is the charging routine specified by virtually every LiFePO4 battery manufacturer. In addition, as mentioned above, it is critical that charging voltage never exceed 3.65V per cell. A quality charger will adhere to all of these requirements.
Temperature compensation
This feature is beneficial for all battery types serviced but is particularly necessary for beneficial charging of LiFePO4 batteries. Essentially, this feature adjusts the charge parameters based on temperature, ensuring that each charging instance gives the battery exactly what it needs.
Low-temperature safeties
LiFePO4 batteries shouldn’t be charged if their temperature is below 32 degrees F (0 degrees C). Some batteries have a BMS that will allow charging energy to flow at temperatures below 32 degrees F, but the general consensus is that charging a LiFePO4 battery that is below 32 degrees F is detrimental to long-term battery health
Managing deep discharge and avoiding severe discharge
Even though they are much better at deep cycling than lead acid batteries and can discharge to 100 percent discharge state, care must be taken when the battery is deeply discharged and it is best to avoid severe discharge (<20 percent SoC). Severe discharge is likely to trigger BMS protections, which can be detrimental to battery health and even cause the battery to reach a state where it cannot be recovered. In deep discharge situations (20-50 percent SoC), a quality charger will deploy a soft start mode to bring the battery back to a regular SoC slowly and safely before providing full power to the battery to finish the charge.
PRO-LOGIX manages LiFePO4 batteries like a champ
The North American market for LiFePO4 lithium batteries is growing quickly. These batteries are now found in a huge variety of applications, as opposed to a few years ago when they were more likely to be found in specific areas, such as powersports applications. So, you may be now encountering them in your world. Perhaps you switched to a LiFePO4 battery in your collector car or your daily driver. Or you have deployed a LiFePO4 battery on your backup sump pump system. Now, you need to service that battery. What are your options?
PRO-LOGIX battery chargers and maintainers are an ideal solution when it comes to servicing LiFePO4 batteries. We have a wide range of products that have specific, dedicated charging routines for LiFePO4 batteries. Plus, each LiFePO4-capable model also has the ability to properly charge various lead acid batteries, from flooded to AGM and spiral wound, so they provide service coverage for virtually every battery type in your stable.
Here’s our lineup of PRO-LOGIX LiFePO4-capable chargers and maintainers. As you will see, we cover virtually every application need:
PL2140 – 6/12V 4.0A Battery Maintainer/Charger
Bumping the power up to 4.0A, the PL2140 is a great all-around unit for servicing batteries of all sizes (18Ah-100Ah). Like the PL2140, it is great for a one-time charge of a depleted battery as well as long-term storage charging of an off-season battery and includes three output options. Like the PL2112, it also can recover from a loss of AC input power, so it is great for long-term charging applications.
PL2310 – 6/12V 10/6/2A Battery Charger/Maintainer
The PL2310 is our base-level full-power charger with 10A output to service a wide variety of vehicle batteries and more. It also adds the ability to provide 12V 10A (0-10A, on demand) power supply function to support a wide variety of diagnostic, repair, and maintenance tasks.
PL2320 – 6/12V 20/10/2A Battery Charger/Maintainer
The PL2320 is identical to the PL2310 but doubles the power. This is the ideal service bay charger for today’s shops, quickly servicing even depleted batteries. Like all PRO-LOGIX models, it features temperature compensation, soft start mode, and battery repair mode to ensure that every battery serviced gets exactly what it needs.
PL2410 – 12/24V 10/6/2A Battery Charger/Maintainer
The calling card of the PL2410 is its 24V operation. It is an amazing charger and can be used for a multitude of tasks, but its reason for existence is its ability to provide service to 24V batteries and systems. Like all PRO-LOGIX chargers, it can even service totally dead (0.0V) lead acid batteries using its forced start mode.
PL6850 – 12/24V 120A Flashing Power Supply and HD Battery Charger
The PL6850 is designed to provide stable power on demand, up to 120 amps, to a vehicle electrical system to support module reprogramming. It is also designed specifically for fleet service battery charging with a maximum charge rate of 120 amps, to quickly and effectively bring 4- and 8-battery Group 31 packs back to full charge.
