I’ve often wondered where the narrative originated that a lithium iron phosphate (LFP, also known as LiFePO4) battery is not a lithium-ion battery. After reading the Renogy blog posts, I now have an answer. This narrative seems to have been created by recreational house battery OEMs as a marketing tactic to distinguish LFP batteries from other lithium-ion batteries.
In reality, a secondary battery (rechargeable, unlike a primary battery) is categorized by the mobile ion used during charging and discharging cycles, not by its chemistry. Like other lithium-ion chemistries, an LFP battery uses lithium ions to move between the cathode and anode, which is why these batteries are often referred to as "rocking chair" batteries. While there are over a dozen types of lithium-ion batteries, only a few are commercially viable and used by retail consumers, including:
Lithium Polymer (LiPo): LiPo batteries are named after the polymer gel used as their electrolyte. These batteries have significantly declined in use and are now primarily found in disposable e-cigarettes.
Lithium Cobalt Oxide (LCO): LCO (LiCoO₂) is the dominant chemistry in 3C batteries (Consumer, Communications, and Computer). Based on the 2-5 year lifespan mentioned in the Renogy blog, it appears LFPs are being compared to LCOs. LCOs are favored for their high specific energy, delivering consistent power over time. They can fast-charge, but this leads to the formation of dendrites—needle-like structures on the anode created from uneven lithium deposits. Dendrites can cause short circuits, leading to thermal runaway (you referred to it as avalanche failure mode). Among lithium-ion chemistries, LCOs have one of the lowest life cycles and shortest calendar life of the consumer available lithium-ion batteries.
Lithium Nickel Manganese Cobalt Oxide (NMC (LiNixMnyCo(1-x-y)O₂): lacks a fixed formula, allowing for varying ratios of nickel, manganese, and cobalt. The Tesla you referenced, depending on its age, could contain different NMC versions. Newer models will have an 8:1:1 ratio of nickel, manganese, and cobalt, while earlier models used ratios like 111, 532, or 622. However, NMCs have largely been phased out of consumer goods like power tools and solar generators due to the growing availability and lower cost of LFPs. While early NMC batteries had shorter lifespans, newer high-nickel versions, such as NMCA90 (which includes aluminum in the cathode), can last 1,500 to 3,000 cycles, or around 10-15 years of use before reaching traditional end-of-life 75-80% of capacity, translating to over 100,000 miles in an EV. NMC batteries also offer higher energy density than LFPs, giving electric vehicles greater range, lower weight of the traction battery, while maintaining thermal stability during fast charging.
Lithium Iron Phosphate (LFP): Most patents for LFP batteries expired by 2022, making them more accessible globally, especially in the West. In China, however, LFP batteries have long been popular due to less strict intellectual property enforcement. LFP batteries are more thermally stable than NMC or LCO, but like all lithium-ion chemistries, they are still susceptible to thermal runaway. It’s possible the Tesla in your photo uses LFP. A common misconception is that lithium-ion batteries "catch fire." What actually happens is that when the battery shorts and its temperature exceeds 200°C, the electrolyte begins to convert into hydrogen and volatile organic compounds like methane and butane, which ignite. Ironically, while some claim that water causes lithium-ion battery fires, it’s not due to lithium itself—there’s no elemental lithium in the battery. Instead, water can cause a short circuit, leading to thermal runaway. Water is used to both extinguish the flames and cool the battery cells until they reach a safe temperature to prevent further combustion.
A study conducted using data from the National Transportation Safety Board (NTSB), the Bureau of Transportation Statistics (BTS), and government recall data found that for every 100,000 EVs sold, there were 25 fires, compared to 1,529 fires per 100,000 internal combustion engine (ICE) vehicles. The reason EV fires seem more frequent is that they make for sensational headlines. Fires caused by consumer goods, such as phones, are even less common than people believe. Over a billion cell phones are sold each year, and only a tiny fraction of them catch fire. However, e-bike batteries are a growing concern, and this could also become an issue with recreational house batteries. Top-tier OEMs like Renogy use Grade A cells, which meet strict quality control standards and pass rigorous testing at the factory. By contrast, Grade B cells found in the majority of these e-bikes and mobility devices, are essentially used or defective batteries sold as new, pose a greater fire risk. These cells, regardless of chemistry, can fail—so choosing cheaper lithium-ion battery, even with the overinflated safety narrative of LFPs may not be the best choice.
Risk management is a complex exercise when done properly and throughly. A traditional way to start is by performing a failure mode effects analysis or FMEA. The basic idea is to identify and analyze each potential failure mode and identify ways to mitigate it if needed. A way to quantify this analysis is the assumption that risk exposure in dollars = probability of failure (no units) X consequence of failure (in dollars). To get at how safe an LFP battery would be in an RV, one might want to do an FMEA for a particular RV and LFO battery combination and compare it to the alternatives under consideration. This is not an easy task unless it is possible to identify a dominate risk exposure that trumps all others. It seems to me that propane is the dominate risk factor unless one had an all electric RV or an RV that derived all of its electricity from non-propane sources. I have heard of such RVs but they are rare in my experience. This is likely because propane can store on the order of 10 times the energy of even an LFP battery and propane is much cheaper than non-propane energy generation systems. As batteries and solar improve, there will be less need for propane but it is with us for now. If someone is concerned about the risks of an LFP battery, they should also be concerned about the risks of propane unless their RV doesn’t use it. Unless they have an EV (which as Mike noted have a giant lithium based battery within them), they would be relying on gasoline or diesel as their ultimate energy source. The larger point is that the risk of adding an LFP battery may be small compared to the other sources of risk exposure present in most RV scenarios. Experience tells us that RV fires (and automobile fires for that matter) are relatively rare but they happen. So, which probability of failure is larger, a non-LFP related fire causing a LFP battery to catch fire or a LFP battery catching fire and causing an RV to catch fire? It’s hard to say. But it’s easy to see that the consequence of failure for either type of fire is very high. To gauge how high, one might look at the amount of energy stored in batteries, propane and gas or diesel in a particular situation. I hope that someone finds this long post to be useful.
I’ve often wondered where the narrative originated that a lithium iron phosphate (LFP, also known as LiFePO4) battery is not a lithium-ion battery. After reading the Renogy blog posts, I now have an answer. This narrative seems to have been created by recreational house battery OEMs as a marketing tactic to distinguish LFP batteries from other lithium-ion batteries.
In reality, a secondary battery (rechargeable, unlike a primary battery) is categorized by the mobile ion used during charging and discharging cycles, not by its chemistry. Like other lithium-ion chemistries, an LFP battery uses lithium ions to move between the cathode and anode, which is why these batteries are often referred to as "rocking chair" batteries. While there are over a dozen types of lithium-ion batteries, only a few are commercially viable and used by retail consumers, including:
Lithium Polymer (LiPo): LiPo batteries are named after the polymer gel used as their electrolyte. These batteries have significantly declined in use and are now primarily found in disposable e-cigarettes.
Lithium Cobalt Oxide (LCO): LCO (LiCoO₂) is the dominant chemistry in 3C batteries (Consumer, Communications, and Computer). Based on the 2-5 year lifespan mentioned in the Renogy blog, it appears LFPs are being compared to LCOs. LCOs are favored for their high specific energy, delivering consistent power over time. They can fast-charge, but this leads to the formation of dendrites—needle-like structures on the anode created from uneven lithium deposits. Dendrites can cause short circuits, leading to thermal runaway (you referred to it as avalanche failure mode). Among lithium-ion chemistries, LCOs have one of the lowest life cycles and shortest calendar life of the consumer available lithium-ion batteries.
Lithium Nickel Manganese Cobalt Oxide (NMC (LiNixMnyCo(1-x-y)O₂): lacks a fixed formula, allowing for varying ratios of nickel, manganese, and cobalt. The Tesla you referenced, depending on its age, could contain different NMC versions. Newer models will have an 8:1:1 ratio of nickel, manganese, and cobalt, while earlier models used ratios like 111, 532, or 622. However, NMCs have largely been phased out of consumer goods like power tools and solar generators due to the growing availability and lower cost of LFPs. While early NMC batteries had shorter lifespans, newer high-nickel versions, such as NMCA90 (which includes aluminum in the cathode), can last 1,500 to 3,000 cycles, or around 10-15 years of use before reaching traditional end-of-life 75-80% of capacity, translating to over 100,000 miles in an EV. NMC batteries also offer higher energy density than LFPs, giving electric vehicles greater range, lower weight of the traction battery, while maintaining thermal stability during fast charging.
Lithium Iron Phosphate (LFP): Most patents for LFP batteries expired by 2022, making them more accessible globally, especially in the West. In China, however, LFP batteries have long been popular due to less strict intellectual property enforcement. LFP batteries are more thermally stable than NMC or LCO, but like all lithium-ion chemistries, they are still susceptible to thermal runaway. It’s possible the Tesla in your photo uses LFP. A common misconception is that lithium-ion batteries "catch fire." What actually happens is that when the battery shorts and its temperature exceeds 200°C, the electrolyte begins to convert into hydrogen and volatile organic compounds like methane and butane, which ignite. Ironically, while some claim that water causes lithium-ion battery fires, it’s not due to lithium itself—there’s no elemental lithium in the battery. Instead, water can cause a short circuit, leading to thermal runaway. Water is used to both extinguish the flames and cool the battery cells until they reach a safe temperature to prevent further combustion.
A study conducted using data from the National Transportation Safety Board (NTSB), the Bureau of Transportation Statistics (BTS), and government recall data found that for every 100,000 EVs sold, there were 25 fires, compared to 1,529 fires per 100,000 internal combustion engine (ICE) vehicles. The reason EV fires seem more frequent is that they make for sensational headlines. Fires caused by consumer goods, such as phones, are even less common than people believe. Over a billion cell phones are sold each year, and only a tiny fraction of them catch fire. However, e-bike batteries are a growing concern, and this could also become an issue with recreational house batteries. Top-tier OEMs like Renogy use Grade A cells, which meet strict quality control standards and pass rigorous testing at the factory. By contrast, Grade B cells found in the majority of these e-bikes and mobility devices, are essentially used or defective batteries sold as new, pose a greater fire risk. These cells, regardless of chemistry, can fail—so choosing cheaper lithium-ion battery, even with the overinflated safety narrative of LFPs may not be the best choice.
Risk management is a complex exercise when done properly and throughly. A traditional way to start is by performing a failure mode effects analysis or FMEA. The basic idea is to identify and analyze each potential failure mode and identify ways to mitigate it if needed. A way to quantify this analysis is the assumption that risk exposure in dollars = probability of failure (no units) X consequence of failure (in dollars). To get at how safe an LFP battery would be in an RV, one might want to do an FMEA for a particular RV and LFO battery combination and compare it to the alternatives under consideration. This is not an easy task unless it is possible to identify a dominate risk exposure that trumps all others. It seems to me that propane is the dominate risk factor unless one had an all electric RV or an RV that derived all of its electricity from non-propane sources. I have heard of such RVs but they are rare in my experience. This is likely because propane can store on the order of 10 times the energy of even an LFP battery and propane is much cheaper than non-propane energy generation systems. As batteries and solar improve, there will be less need for propane but it is with us for now. If someone is concerned about the risks of an LFP battery, they should also be concerned about the risks of propane unless their RV doesn’t use it. Unless they have an EV (which as Mike noted have a giant lithium based battery within them), they would be relying on gasoline or diesel as their ultimate energy source. The larger point is that the risk of adding an LFP battery may be small compared to the other sources of risk exposure present in most RV scenarios. Experience tells us that RV fires (and automobile fires for that matter) are relatively rare but they happen. So, which probability of failure is larger, a non-LFP related fire causing a LFP battery to catch fire or a LFP battery catching fire and causing an RV to catch fire? It’s hard to say. But it’s easy to see that the consequence of failure for either type of fire is very high. To gauge how high, one might look at the amount of energy stored in batteries, propane and gas or diesel in a particular situation. I hope that someone finds this long post to be useful.