If you are looking for a reliable and efficient energy storage solution you might be wondering whether to choose lifepo4 or lead-acid batteries. Both types of batteries have their advantages and disadvantages, depending on your needs and preferences. In this article, we will compare lithium and lead-acid batteries in terms of performance, durability, cost, and environmental impact, to help you make an informed decision.
Performance
One of the most important factors to consider when choosing a battery is its performance, which includes its capacity, power, efficiency, and lifespan.
Capacity
The capacity of a battery is the amount of energy it can store and deliver. It is measured in amp-hours (Ah) or watt-hours (Wh). The higher the capacity, the longer the battery can run your appliances and devices.
Lithium batteries have a higher capacity than lead-acid batteries of the same size and weight. For example, a 100Ah lithium battery can provide 100Ah of usable energy, while a 100Ah lead-acid battery can only provide 50Ah of usable energy at best. This is because lithium batteries can be discharged up to 100% depth of discharge (DoD), while lead-acid batteries should not be discharged below 50% DoD to avoid damaging the cells.
Power
The power of a battery is the rate at which it can deliver energy. It is measured in watts (W) or amps (A). The higher the power, the faster the battery can charge and discharge, and the more appliances and devices it can run simultaneously.
Lithium batteries have a higher power than lead-acid batteries of the same capacity. For example, a 100Ah lithium battery can deliver up to 200A of continuous current, while a 100Ah lead-acid battery can only deliver up to 100A of continuous current. This is because lithium batteries have a lower internal resistance than lead-acid batteries, which means they can handle higher currents without overheating or losing efficiency.
Efficiency
The efficiency of a battery is the ratio of the energy output to the energy input. It is expressed as a percentage (%). The higher the efficiency, the less energy is wasted during charging and discharging.
Lithium batteries have a higher efficiency than lead-acid batteries. For example, a lithium battery can have an efficiency of up to 98%, while a lead-acid battery can have an efficiency of around 80%. This means that lithium batteries can store and deliver more energy from the same amount of solar input or generator output than lead-acid batteries.
Lifespan
The lifespan of a battery is the number of charge and discharge cycles it can undergo before its capacity drops below 80% of its original value. The higher the lifespan, the longer the battery can serve you before needing replacement.
Lithium batteries have a longer lifespan than lead-acid batteries. For example, a lithium battery can last up to 2000 cycles at 100% DoD, while a lead-acid battery can last up to 600 cycles at 50% DoD. This means that lithium batteries can endure more frequent and deeper cycling than lead-acid batteries without losing much capacity.
Durability
Another factor to consider when choosing a battery is its durability, which includes its resistance to temperature, vibration, and corrosion.
Temperature
The temperature of the environment where the battery is installed and operated can affect its performance and lifespan. Extreme temperatures can cause thermal stress, expansion, contraction, and chemical reactions that can damage the cells.
Lithium batteries are more resistant to temperature than lead-acid batteries. For example, lithium batteries can operate in a wider temperature range than lead-acid batteries, from -20°C to +60°C. They also have built-in battery management systems (BMS) that monitor and regulate the temperature of each cell to prevent overheating or freezing. Lead-acid batteries are more sensitive to temperature changes and require more ventilation and insulation to maintain optimal performance.
Vibration
The vibration of the vehicle or vessel where the battery is installed and operated can also affect its performance and lifespan. Excessive vibration can cause physical damage, loose connections, and internal short circuits that can reduce the capacity and power of the battery.
Lithium batteries are more resistant to vibration than lead-acid batteries. For example, lithium batteries are made of solid-state cells that are tightly packed and sealed in sturdy cases that prevent movement and leakage. They also have BMS that protect them from short circuits and overloads. Lead-acid batteries are made of liquid electrolyte and plates that are prone to spilling and sulfation under vibration.
Corrosion
The corrosion of the terminals and connectors of the battery can also affect its performance and lifespan. Corrosion can cause increased resistance, reduced conductivity, and poor contact that can reduce the capacity and power of the battery.
Lithium batteries are more resistant to corrosion than lead-acid batteries. For example, lithium batteries have stainless steel or brass terminals and connectors that are less likely to rust or oxidize than lead-acid batteries. They also have BMS that prevent overcharging and undercharging that can cause corrosion.
Cost
The cost of a battery is another factor to consider when choosing a battery. It includes the initial purchase price, the installation cost, the maintenance cost, and the replacement cost. But in 2024, its usually far cheaper per cycle to purchase a Lifepo4 battery. Usually 5-10 times cheaper or more.
Purchase Price
The purchase price of a battery is the amount of money you pay upfront to buy the battery. It is usually based on the capacity, power, and quality of the battery.
Lithium batteries have a higher purchase price than lead-acid batteries of the same capacity and power. For example, a 100Ah lithium battery can cost around $400-$600, while a 100Ah lead-acid battery can cost around $300-$600. This is because lithium batteries use more advanced and expensive materials and technologies than lead-acid batteries, but recently the competition of Lithium Iron Lifepo4 has lead to very similar prices
Installation Cost
The installation cost of a battery is the amount of money you pay to install the battery in your vehicle or vessel. It is usually based on the size, weight, and complexity of the battery.
Lithium batteries have a lower installation cost than lead-acid batteries of the same capacity and power. For example, a 100Ah lithium battery can weigh around 12kg and take up around 20L of space, while a 100Ah lead-acid battery can weigh around 30kg and take up around 40L of space. This means that lithium batteries are easier and cheaper to install than lead-acid batteries, especially in tight and limited spaces.
Maintenance Cost
The maintenance cost of a battery is the amount of money you pay to maintain the performance and lifespan of the battery. It is usually based on the frequency, complexity, and necessity of the maintenance tasks.
Lithium batteries have a lower maintenance cost than lead-acid batteries. For example, lithium batteries are maintenance-free and do not require any watering, equalizing, or cleaning. They also have BMS that monitor and regulate their performance and health. Lead-acid batteries require regular maintenance such as watering, equalizing, cleaning, and checking for corrosion and sulfation. They also need external regulators to prevent overcharging and undercharging.
Replacement Cost
The replacement cost of a battery is the amount of money you pay to replace the battery when it reaches the end of its lifespan. It is usually based on the lifespan, availability, and recyclability of the battery.
Lithium batteries have a lower replacement cost than lead-acid batteries. For example, lithium batteries can last up to four times longer than lead-acid batteries, which means they need to be replaced less often. They are also more widely available and recyclable than lead-acid batteries, which means they are easier and cheaper to dispose of.
Environmental Impact
The environmental impact of a battery is another factor to consider when choosing a battery. It includes the energy consumption, greenhouse gas emissions, waste generation, and resource depletion associated with the production, use, and disposal of the battery.
Energy Consumption
The energy consumption of a battery is the amount of energy required to produce, charge, and discharge the battery. It is usually based on the efficiency, lifespan, and capacity of the battery.
Lithium batteries have a lower energy consumption than lead-acid batteries. For example, lithium batteries can store and deliver more energy from the same amount of solar or generator input than lead-acid batteries due to their higher efficiency. They also need less energy to produce due to their longer lifespan and smaller size.
Greenhouse Gas Emissions
The greenhouse gas emissions of a battery are the amount of carbon dioxide (CO2) and other gases released into the atmosphere as a result of the production, use, and disposal of the battery. They are usually based on the energy consumption, energy source, and recycling rate of the battery.
Lithium batteries have lower greenhouse gas emissions than lead-acid batteries. For example, lithium batteries can reduce CO2 emissions by up to 50% compared to lead-acid batteries due to their lower energy consumption and higher recycling rate. They also use renewable energy sources such as solar or wind more efficiently than lead-acid batteries due to their higher efficiency.
The production and carbon costs of Lead Acid vs Lithium, are very hard to know, with some saying Lithium is much worse, and it’s true that mining lithium and Iron and the other metals required may have a higher carbon footprint, but if you are using the battery daily, these will eventually become less.
Cranking Amps compared
When comparing cranking amps between LiFePO4 (Lithium Iron Phosphate) and lead-acid batteries, there are some important distinctions:
LiFePO4 Batteries:
LiFePO4 batteries are more effective at delivering a large amount of current over a short period.
They are particularly suitable for applications where high cranking power is needed, such as starting engines or powering devices with significant initial current demands.
For instance, if you require a battery that can sustain a 40-amp device for two hours straight, LiFePO4 is an excellent choice
Lead-Acid Batteries:
Lead-acid batteries have been around for a long time and are commonly used in various applications.
While they have their advantages, such as being cost-effective, they are not as efficient as LiFePO4 batteries in terms of cranking amps.
Lead-acid batteries may struggle to deliver high current consistently over a short duration compared to LiFePO4 batteries.
In summary, if you prioritize high cranking power and need a battery that can handle substantial current demands, LiFePO4 is the way to go.
Lets start with The Kings 120Ah Lithium LiFePO4 Battery it’s a reliable and versatile energy storage solution. Let’s explore its features:
Capacity and Chemistry:
The battery has a capacity of 120Ah (ampere-hours).
It utilizes Lithium Iron Phosphate (LiFePO4) chemistry, which offers several advantages:
Lightweight: Weighing just over 15 kg, it’s easy to handle.
Long Life: It provides 2000+ cycles at 80% depth of discharge. The cells used are approx. 3000 cycle cells. They are not Automotive Grade. But almost no battery does include Automotive grade cells. When used in a battery pack, the cells will not give as many cycles.
Kings prioritizes quality by integrating a robust BMS.
With its impressive cycle life, this battery can serve you reliably over the long term.
Remember to follow proper charging practices and safety guidelines to maximize the lifespan of your Kings 120Ah Lithium Battery.
We 100% recommend the kings 120Ah lithium battery for those who do not want to spend all their money on their setup. There are better batteries out there. But 98% aren’t that much better to demand 5 times the price.
VOLTX 100ah Lifepo4 Battery Review.
The VoltX 12V 100Ah LiFePO4 Basic Lithium Battery has garnered positive reviews from users. Let’s delve into some feedback:
Richard B. from Metropolitan Adelaide, SA:
Describes the battery as “faultless” and praises its bargain price.
Used it for over 6 months without issues.
Runs two fridges (40L & 60L) for days on end, primarily charged via solar.
His brother also purchased one with similar success.
Udo:
Calls it “perfect” and great value for the money.
Works well for his off-grid setup.
Goona:
Labels it a “brilliant battery” that outlasts AGM batteries.
Faster charging and significantly lighter.
Going strong for almost 3 years.
Keith Wilkinson from South East Queensland, QLD:
Replaced a 120AH AGM with this battery.
Powers a chest freezer through a 3000W inverter.
Reliable even after cloudy days.
Mark:
Appreciates its lightweight (half the weight of AGM).
Runs fridges and an inverter without issues.
Steve K:
Loves it for camping with a 75L fridge.
No more messy ice-filled eskies.
SUMMARY Both of these batteries are basic with no Bluetooth or management options, but they both do what they say. The Kings battery has the advantage of larger capacity, but also with many retail locations you can always get customer service if required. It should be noted that at this price point, The warranty is a mere 12 months. But for the price, I think its pretty fair, Its likely the batteries will last a few years, but without a warranty. You might be unlucky and get a dud!
Remember that individual experiences may vary, but overall, the VoltX 12V 100Ah LiFePO4 Basic Lithium Battery seems to be a solid choice for various light applications, and I would choose a voltx battery over any Lead Acid battery every day of the week.
The 200MW/400MWh battery energy storage system (BESS) is live in Ningxia, China, equipped with Hithium lithium iron phosphate (LFP) cells.
Established 3 years ago in 2019 is already ramping up to a target of more than 135GWh of annual battery cell production capacity by 2025 for a total investment value of about US$4.71 billion.
The project was connected to the grid earlier this month, through a system integrator called ROBESTEC, about which little information appears publicly available. However, it is understood that although Hithium makes and provides complete BESS solutions as well as cells, in this case, it was the cell supplier.
200MW/400MWh HITHIUM LFP BESS in China
The facility stores energy at times of abundant generation from solar PV and wind, putting it into the grid during times of peak demand. It will also help regulate grid frequency.
If you are interested in these new 280AH cells, which Hithium and CATL currently can produce specifically for ESS use, let us know, as we have access to the cells when the demand is slightly lower. As these are actually in high demand for commercial applications, and they technically are hard to get for the DIY community.
it’s expected this giant LFP battery will cut CO2 emissions by 501,000 tons per year
Hithium specializes in the R&D, production, and sales of LFP energy storage batteries and systems. With strong customer orientation, they are committed to providing safe, efficient, clean, and sustainable energy storage solutions for the world. Hithium now has over 4400 employees globally including over 1000 R&D engineers with extensive experience in energy storage. With a planned 4.71 billion USD total investment and 1,400,000m2 factory space to achieve 135GWh production capacity of the energy storage battery in 2025.
Hithium-280ah-LFP280 12000 Cycles Storage Grade
Hithium_280ah_test_results
We delivered these cells in 2022 to a few customers and currently have a small shipment arriving again in February 2023. As they are an unknown brand to many customers, we haven’t ordered large quantities, because many customers still want EVE, CATL, LiShen, CALB, and various other brands they have heard of. It’s just not a well-known brand,
In the past was a bad thing, But with this type of new technology, sometimes it’s a great thing to get in early while you can.
The 12v solar panel market in Australia is about as bad as Aliexpress. Advertised panel outputs are grossly exaggerated, usually by 200-300%.
This post will be short and sweet, but some very simple math allows us to work out rough outputs from the panels available on eBay and even reputable retailers such as 4×4 Supacentre and online marketplaces such as www.catch.com.au.
A solar panel is usually something like 15-18% efficient in the 12v marketplace. It is extremely rare that they will actually output 20% or higher and if they do, they are probably 10x times more expensive than what you are looking at paying on the online marketplaces.
An example of what to expect from an eBay 350w solar panel is probably something like 80-120W. If you work out that 1000w of sunlight falls per metre squared that is STC and the panel is 1270mm x710mm and area of about 0.9m2. You can multiply that by 0.15 (15%) to get the wattage (if you need the calculation, do a google search). So, anyhow 0.9 x 0.15 is 135w. Now add in the NOCT rule of thumb, reduce that number by about a quarter and you will get 101w of power from that solar panel under normal operating conditions.
Given that you are paying about $170 for that panel. You are actually paying far too much for those solar panels you buy online and losing valuable roof space as a consequence.
Some people have caravans and off-grid requirements, so recently people have been looking to the house panel marketplace, this is a better option but only if you have the space available to install that size panel, and it also means your voltage may increase, which is fine as long as you take that into consideration.
It is illegal in Australia to work on any DC electrical system or panels with a voltage higher than 50V DC. This means you need to ensure you don’t run the panels in series of anything higher than that number unless you are a licensed electrician with the appropriate qualifications.
There are some exceptions to the marketplaces with Vendors such as Renogy. They actually do offer a more realistic wattage for their products, of course, you should still take roughly a quarter off the advertised wattage, because of the NOCT (normal operating conditions) rule. But at least you know what you are actually buying.
We will soon create a buyers guide and even list some good quality products on our website, so you don’t have to get ripped off buying completely rubbish claims made by online retailers.
Recently we watched Will Prowse review a OEM battery that we can and have been able to source in small quantities for some time, one of our trusted suppliers sent us one of these Batteries for review last year, this battery is a made-to-specification battery by one of the largest LIFEPO4 drop-in replacement manufacturers in China. You probably have some questions you want to know the answer about China and the Lithium drop-in replacement industry, because its really hard to know who is making and selling what. And its an eye opening journey.
Over the past few years, a few of the OEM Battery suppliers have come up with some reliable and high quality drop-in replacements. This is one of the reasons Will has only recently discovered these better quality OEM batteries. Because they have been a work in progress, as each company gets a little better, so do the batteries they produce.
If you think, it’s actually in the best interest of both the consumer and the manufacturer to make a battery that does work and doesn’t fail. The competitive nature of business drives the improving product all the time.
We have been testing batteries like this since 2015. And they have been available in a similar form since about 2014 from these manufacturers.
What has happened is that the product has matured, they have got to the point where the BMS is very reliable, and the cells are better than what most people need.
To find out why we won’t be importing this Weize 12V 100Ah LiFePO4 Battery in bulk read along further
Questions
Q. Can we get this in 50ah, 100ah, and 200ah capacity from the same manufacturer? A. Yes, we can
Q. Will we be ordering these into stock? A. No, we won’t, because there are too many brands of 12v 100ah drop-in, already on the market, and we would prefer to only bring in products we love and recommend for our customers.
Q. How much would we charge for this? A. Not as much as you might think, being Amazon is very competitive, the price of this is $350-450USD.
Lets do some quick math. based on the 2 prices $350USD and $450USD.
As you can see, there is no real business case for importing these into Australia. In fact they are already here, just labelled with a different brand. I know these are here in the $600-1000 range already.
It does make you wonder, should you buy a $400 eBay battery or should you buy a $2000 Enerdrive? In my view, I would buy somewhere in the middle, but I also build my own batteries which I prefer, as I can choose which cells I use, and which BMS I use, and that is exactly why we at Lifepo4 Australia choose to use the EVE and Ganfeng lithium cells primarily, because they are both A grade products, and they both use Australian Lithium inside them.
I don’t know about you but if Victron would just release a 100ah battery for $600-800, they would destroy every other battery retailer in one go. As long as it had 4 Series and 4 parallel, with an easy to use management software for when it’s used in various configurations. Victron would absolutely own the market.
1. China – CATL 2. South Korea – LG Chem 3. Japan – Panasonic
These 3 Brands enjoyed a combined EV battery market share of 68%, according to Goldman Sachs’ estimates in 2020/21 FY.
#1 CATL – Contemporary Amperex Technology Co. Limited, abbreviated as CATL, is a Chinese battery manufacturer and technology company founded in 2011 that specializes in the manufacturing of lithium-ion batteries for electric vehicles and energy storage systems, as well as battery management systems.
#2 LG Chem Ltd often referred to as LG Chemical, is the largest Korean chemical company is headquartered in Seoul, South Korea. first established as the Lucky Chemical Industrial Corporation, which manufactured cosmetics. It is now solely a business-to-business company.
#3 Panasonic – Famous around the world, a japanese conglomorate who has been enourmously successful for decades #5 BYD – The newest entrant here, Build YOUR DREAMS is an AMAZING COMPANY THAT IS GOING TO BE ONE OF THE LARGEST COMPANIES IN THE WORLD WITHIN 5-10 YEARS #4 CALB
Want to know how to take care of your valuable new purchase: the best way to charge lithium batteries, how to discharge them, and learn how to maximize their life? This article explains the pros and cons.
Lithium-ion battery prices are slowly changing from obscenely expensive to just almost on par with traditional Lead Acid, and we at LiFePo4 Australia tend to find most users using them in Caravans, fifth wheels, RVs, and the like Vehicles while some are jumping into stationary off-grid systems.
The specific category of lithium-ion batteries; Lithium Ferro (iron) Phosphate or LiFePO4 in its chemical formula, also abbreviated as LFP batteries. This is a little different from what you have in your cell phone and laptop. These are (mostly) lithium cobalt batteries. The advantage of LFP is that it is much more stable and not prone to self-immolation. This does not mean that if the battery is damaged, it will not burn: there is a fair amount of energy stored in a charged battery, and in the event of an unplanned discharge, the results can be obtained Very interesting, very quick! Compared to lithium cobalt, LFP also lasts longer and is more temperature stable. Of all the different lithium battery technologies, this makes LFP best suited for deep cycle applications! no. BMS takes care of battery protection; disconnects the battery when it is discharged or overcharged. BMS also cares about limiting charge and discharge currents, monitors the cell temperature (and limits charge/discharge if necessary), and most of them balance each cell with a full charge time (think of balancing as bringing all cells inside the battery to the same state of charge, similar to the equalization for a lead acid battery) Unless you like living on the edge, DO NOT BUY a battery without a BMS! Below is the knowledge gained from reading a large number of web articles, blog pages, scientific publications, and discussions with LFP manufacturers. which we are writing about here is by no means intended as the ultimate guide to LFP batteries, we hope this article will bypass cattle excrement and give you solid tips on how to get the most out of lithium-ion batteries.
An image of the popular JBD 200 amp 4s 12v BMS for LFP and Lithium Batteries
Why lithium-ion? We explained in our lead-acid battery article how that chemistry’s Achilles heel stays at a partial charge for too long It’s too easy to damage an expensive bank of lead-acid batteries in a few months by letting it sit at partial charge This is very different for LFP! You can let lithium-ion batteries stay partially charged forever without damage, LFP prefers to stay partially charged rather than full or empty, and for longevity, it is best to cycle the battery or let it sit partially charged. Lithium-ion batteries are currently what I would call the holy grail of batteries – with the right charging parameters you can almost forget there’s a battery. Maintenance. The BMS will take care of it and you can safely go cycling!
LFP batteries can also last very long. The once famous USA-made Battle Born LFP batteries are rated for 3000 cycles, with a full 100% charge/discharge cycle. If you do this every day, it gives you over 8 years of cycling! even longer when used in cycles less than 100%, in fact, for simplicity, a linear relationship can be used: 50% discharge cycles mean twice as many cycles, 33% discharge cycles, and you can reasonably expect three times the number of cycles. A LiFePO4 battery also weighs less than half that of a lead acid battery of similar capacity. It can withstand large charging currents (100 Ah rating is no problem, try it with lead acid! ) to allow for fast charging, it’s sealed to prevent fumes and it has a very low self-discharge rate (3% per month or less).
Lithium-Ion vs. Lead Acid
As of 2020 a Battle Born 12V 100Ah battery costs $950 US dollars ($1400-1500AUD). The full 100Ah is usable, so 12.8 x 100 = 1,280-watt-hours of energy storage or just under $1.50 AUD per Wh of usable energy storage. One of the best – bang-for-buck-deep-cycle lead-acid batteries is currently on sale at approx $300 for 12v 120Ah. With lead-acid only 50% is really usable. so we have 12 x 120 x 0.5 = 770wh energy storage. That makes 400/60 = $ 0.67 AUD per Wh of usable energy storage.
This is where you say, “Wait a minute, those dam $ lithium batteries cost nearly twice the price of lead acid!”! Immediately followed by “but I still want one!” And you’re right: We haven’t determined the difference in battery life yet. A very good quality Lead Acid is suitable for around 1000 cycles at 50 ° discharge (DOD) during the battle Born does 6000 cycles with the same 50% DOD. This means that the lithium-ion battery will last about 6 times as long! Over the life of a single set of LFP batteries, the cost per usable Wh for lead acid is now 6 x 0.50 = $ 3.00, making lithium ions half the price! But wait, who even buys a Battleborn is Australia? No one, But it’s still a good example. If we were talking about SolarKing or iTechworld the LiFePO4 would be twice as good value. However, any of the much more expensive brands like Victron and Enerdrive would be more in line with BattleBorn. There is so much more: in real life, very few people will get the full life cycle of lead-acid batteries
Apply this to the Chinese-made 100ah drop-ins. The cost is cheaper for LiFePo4! It’s a no-brainer!
It is too easy for them to take offense at your treatment and leave prematurely for the Big Battery in the Sky, if you make them go far, there is water, specific gravity measurement, and taking care to recharge them regularly to prevent them from sulfating, none of this is necessary for lithium ions! We bet at this point you are starting to consider these Lithium Ions!
Battery Bank Sizing
Battery bank sizing for LFP I mentioned above: LFP batteries have a best practice usable capacity of 90%, while lead-acid really ends up at 50%. This means you can size an LFP battery bank smaller than a lead-acid bank and functionally it’s the same. The numbers suggest that LFP may be 55-60% of the amp-hour size of the lead acid. However, there is more. For longevity, lead acid battery banks should not be sized where they regularly see discharges below 50% SOC. With LFP this is not a problem! Round-trip energy efficiency for LFP is also a lot better than lead-acid, which means less energy is needed to fill the tank after a certain level of discharge. faster recovery up to 100%, while we already had a smaller battery bank, further reinforcing this effect. The bottom line is that it would be handy to size a lithium-ion battery bank to 55% – 60% the size of an equivalent lead-acid bank and expect the same (actually better!) performance. Even on those dark winter days when the sun is scarce. This also means you can basically use half the solar panel size array, just because of this difference, you now need a smaller system overall. Making LFP the clear winner in every possible scenario.
Beware of batteries connected in series!
There is a potential problem when multiple Li-ion batteries are connected in series. For example, two 12 Volt 100 Ah batteries, each with their own built-in BMS, are connected in series to produce 24 Volt 100 Ah. Now assume that one of these two batteries is almost empty, the other quite full, and put a load on the batteries to discharge them. The low battery will reach the point where the BMS first decides “enough is enough” and shut down that battery, effectively disconnecting the entire battery bank, even if the other battery is still full. The same potential for trouble exists when charging both batteries simultaneously with a 24 Volt charging source. two batteries will fill first, increasing the charge voltage on that battery, until it reaches the point where the BMS once again steps in to protect the battery and shut down the full battery. When the BMS shuts down, the entire bank of batteries “goes. If both started erratically, the other battery may not be fully charged yet, and this will not resolve over time or even with multiple charge cycles. . Moral of this story is that you should understand the dynamics of connecting multiple lithium-ion batteries in series. They don’t behave quite like lead-acid batteries! Lead-acid batteries self-balance when charged, all reaching a similar state of charge in the end. Lithium-ion batteries because each has its own independent BMS. From experience, we know that connected batteries in series, each with its own BMS, can function properly. It would be a good idea to make sure the two are ‘in sync’ every now and then, charging them individually with a 12-volt charger, until both are fully charged, so they start with the same state of charge.
Temperature of LFP
But wait a minute! Is lithium-ion really the solution to all our battery woos? Well, not quite… LFP batteries also have their limits. One big problem is temperature: you cannot charge a lithium-ion battery below zero Celcius. Lead acid does not care. You can still discharge the battery (with temporary loss of capacity), but the charging will not occur. The BMS should take care to block the charge in freezing temperatures, avoiding accidental damage. This is a possible problem in our Australian climate! Temperature is also an issue at the high end. The main cause of aging batteries is use or even just storage at high temperatures. Up to about 30 degrees centigrade, there is no problem, even 45 degrees centigrade does not incur an excessive penalty, anything higher really accelerates aging and eventually the end of the battery, however, this includes storing the battery in a shaded possibly cooled environment.
There is a sneaky problem that can arise when using charging sources that potentially provide high voltage: when the battery is full, the voltage will rise, unless the charging source stops If it gets up high enough, the BMS will protect the battery and disconnect it, letting the charging source go up even more! This can be a problem with the car (bad) alternator voltage regulators, which must always see a load or the voltage will spike and the diodes will release their magic smoke. This can also be a problem with small wind turbines. which rely on the battery to keep them in check. They could possibly destroy an LFP battery. Then there’s that high initial purchase price! But we bet you still want one!
How does a LiFePO4 battery work?
LiFePO4 Internal structure Lithium-ion batteries are referred to as a type of “ rocking chair ” battery: they move ions, in this case, lithium ions, from the negative to the positive electrode during discharge and vice versa always during charging. The drawing on the right shows what is happening inside. The red balls are the lithium ions, which move back and forth between the negative and positive electrodes. On the left side is the positive electrode, constructed from iron phosphate (LiFePO4). This should help explain the name of this type of battery! The iron and phosphate ions form a grid that freely traps the lithium ions. When the cell charges, those lithium ions are drawn through the membrane into the center, to the negative electrode on the right. The membrane is made from a type of polymer (plastic), with many tiny pores inside it, which facilitate the passage of lithium ions. On the side we find a lattice made of carbon atoms, which can trap and hold those lithium ions that cross. The battery is discharged in reverse order: When electrons flow away through the negative electrode, the lithium ions move again through the membrane back to the iron-phosphate grid. They will again be saved on the positive side until the battery is recharged. Almost all lithium ions are on the positive electrode side. In a charged battery, these lithium ions would all be stored in the carbon of the negative electrode. In the real world, lithium-ion cells consist of very thin layers of alternating aluminum-polymer-copper foils, The chemicals are stuck to it. Rolled up like a jelly roll and put in a steel container, similar to an AA battery. The 12 volt lithium ion batteries you buy are made up of many of these cells connected in series and in parallel in order to increase the voltage and ampere-hour capacity. Each cell is roughly 3.3 volts, so 4 of them in series makes 13. 2 volts This is the correct voltage to replace a 12-volt lead acid battery!
Charging an LFP Battery from solar
Most regular solar charge controllers have no problem charging lithium-ion batteries
The voltages required are very similar to those for AGM batteries (a type of sealed lead-acid battery). The BMS also helps to secure the battery cells to see the correct voltage, do not get overcharged or over-discharged, balance the cells and ensure that the cell temperature is within the reasonable range while charging. The following graph shows a typical Profile of a LiFePO4 battery being charged Make it easy to see the voltages that have been converted to what a 12-volt LFP battery would see (4x the single cell voltage). LiFePO4 charge voltage vs.SOC LiFePO4 charge voltage vs or half the Ah capacity, in other words for a 100 Ah battery this would be a charge rate of 50 amps. The charge voltage (in red) doesn’t change that much for LFP batteries with higher or lower charge rates (in blue) they have a very flat voltage curve. Lithium-ion batteries are charged in two stages: first, the current is kept constant, or with solar PV, which usually means we try to send as much current into the batteries as is available from the sun. the voltage will slowly increase during this time, until it reaches the “ absorption ” voltage, 14.6V in the graph above.
Once the absorption is reached, the battery is full to about 90 %, and to fill it the rest of the time, the voltage is kept constant while the current slowly decreases. Once the current drops to about 5% – 10% of the battery’s Ah rating, it is at 100% of l ‘state of charge. In many ways, a lithium-ion battery is easier to charge than a lead-acid battery: as long as the charging voltage is high enough to displace the ions it is charging. ion does not care if they are not fully 100% charged, in fact, they last a long time if they are not. There is no sulfation, there is no equalization, absorption time does not really matter, you cannot really overcharge the battery, and the BMS takes care to keep things within reasonable limits. Required charging voltage So what voltage is enough to move these ions?6 Volts (3.4 V per cell) is the breakpoint; below this very little happens, while above this the battery will fill up to at least 95% given enough time At 14.0 Volts (3.5 V per cell) the battery easily charges up to 95+ percent with a few hours of time absorption and for all intents and purposes and for purposes there is little difference in charging between voltages 14.0 or higher, things just happen a little faster at 14.2 Volts and above. it will work great for LiFePO4! With the help of a certain absorption time, a decrease to around 14.0 volts is also possible. Slightly higher voltages are possible. The BMS for most batteries allows about 14.8 to 15.0 volts before the battery is disconnected. There is no benefit to higher voltage but there is a higher risk of being cut off by the BMS and possible damage. Float Voltage LFP batteries do not have to be floatable. Charge controllers do this because lead-acid batteries have such a high rate of self-discharge that it makes sense to keep adding more and more charges to keep them happy. It is not good for lithium-ion batteries if the battery is constantly in a high state of charge. If your charge controller cannot deactivate the float, simply set it to a low enough voltage that actual charging will not occur. Any voltage from 13. 6 Volts or less. Equalize Voltage With charging voltages above 14.6 Volts actively discouraged, it should be understood that no equalization should be performed on a Li-ion battery! If the equalization cannot be disabled, set it to 14.6V or less, then it becomes just a normal absorption charge cycle.
Absorption time
There is a lot to be said for just setting the absorption voltage to 14.4V or 14.6V, and then stop charging once the battery reaches that voltage! In short, zero (or short) absorb time. At that point, the battery will be about 90% full. LiFePO4 batteries will be happier in the long run when they don’t stay at 100% SOC for too long, so this practice will extend your battery life. If you absolutely must have 100% SOC in your battery, absorb it will do! Officially, this is achieved when the charging current drops to 5% – 10% of the battery Ah value, i.e. 5-10 Amp for a 100Ah battery If you cannot stop absorbing the current, set the absorption time to about 2 hours and call Temperature compensation LiFePO4 Batteries do not require temperature compensation! Turn this off in the charge controller, otherwise, the charge voltage will be wildly turned off when it is very hot or cold. Check the voltage settings of the charge controller against actual voltage measured with a good quality DMM! Small changes in voltage can make a big difference during charging a lithium-ion battery! Change the charge settings accordingly!
Discharging an LFP Battery
Unlike lead acid batteries, the voltage of a lithium-ion battery remains very constant during discharge, making it difficult to guess the state of charge from the voltage alone. For a battery with a moderate load, the discharge curve seems LiFePO4 Discharge voltage vs. discharge voltage SOC LiFePO4 vs. SOC Most of the time during discharge, the battery voltage will be just around 13.2 volts. it was a really bad idea ™ to go below 20% SOC for a LiFePO4 battery. This has changed and the current LFP battery harvest will quite happily discharge down to 0% for many cycles. However, there is an advantage in pedaling less deep. It’s not just that going to 30% SOC will get you 1 / 3 cycles more than 0%, the battery will likely last more cycles than that. The hard numbers are, well, hard to find, but the cycle up to 50% SOC seems to show about 3 times the cycle life compared to .cycling 100%. Below is a table showing the battery voltage for a 12 Volt battery pack with respect to depth of discharge. Take these voltage values with a pinch of salt, the discharge curve is so flat that it is really difficult to determine SOC from voltage alone: small variations in load and accuracy of the voltmeter will negate the measurement.
LiFePo4 SOC Chart
% SOC
VOC
0.2C
100%
14.0 Volt
13.6 Volt
99%
13.8 Volt
13.4 Volt
90%
13.4 Volt
13.3 Volt
70%
13.2 Volt
13.2 Volt
40%
13.2 Volt
13.1 Volt
30%
13.0 Volt
13.0 Volt
20%
12.9 Volt
12.9 Volt
17%
12.8 Volt
12.8 Volt
14%
12.6 Volt
12.5 Volt
9%
12.4 Volt
12.0 Volt
0%
10.4 Volt
10.0 Volt
Storing lithium-ion batteries
The very low self-discharge rate makes it easier to store LFP batteries, even for longer periods of time. It is not a problem to put a lithium-ion battery away for a year, but make sure it is charged beforehand. Storing between 50% and 60% is ideal as the battery takes a very long time before self-discharge near voltage Storing batteries below freezing is fine even at very low temperatures than -40 degrees Celsius (which is the same in Fahrenheit) or even less! The electrolyte in LiFePO4 cells does not contain any water. Even if it freezes (which happens at around -40 degrees Celsius depending on the formulation), this is not the case. Allow the battery to warm up a little before discharging it again. This is fine at -20 degrees Celsius and above. When discharging at temperatures below freezing point, an obvious loss of capacity occurs, reversed when the battery rises above freezing point and has a slightly accelerated effect on aging. Storage at low temperatures is certainly much better than storage at high temperatures: the aging of the calendar slows down dramatically at low temperatures. Avoid storing them at 45 degrees Celsius and above, and try to avoid keeping them as full (or almost empty) as possible. If you need to store batteries for a long time, just unplug all cables from them. In this way, there can be no parasitic charges which slowly discharge the batteries.
The end of your lithium-ion batteries We can hear you gasp in horror; the idea that your precious LFP battery bank is no longer thrills you! Alas, all good things have to come to an end eventually. What we want to avoid is the premature (and perhaps spectacular) end of the genre, which makes us have to understand how lithium-ion batteries die. Many batteries consider a battery to be “dead” when its capacity drops to 80% of what it should be. Thus, for a 100Ah battery, its end comes when its capacity is reduced to 80Ah There are two mechanisms at work for the disappearance of your battery: cycling and aging. Each time you discharge and recharge the battery, it does a bit of damage and you lose a bit of capacity. But even if you put your precious battery in a beautiful, glass-enclosed sanctuary, never to be rolled, it will always come to an end.
LiFePo4 Lifespan
The latter is called lifespan. Calendar It is difficult to find reliable data on the calendar life of LiFePO4 batteries, very little is available. Some scientific studies have been conducted on the effect of extremes (temperature and SOC) on calendar life and these help set limits. What we gather is that if you don’t abuse the battery bank, avoid extremes and generally only use the batteries within reasonable limits, there is a maximum limit of about 20 years on calendar life. In addition to the cells inside the battery, there is also the BMS, which is made up of electronic parts. When the BMS fails, the battery will be too. ion batteries with a built-in BMS are still too new, and we’ll have to see, but ultimately the battery management system has to survive for as long as lithium-ion cells do. The processes within the battery conspire over time to coat the boundary layer between the electrodes and the electrolyte with chemical compounds that prevent lithium ions from entering and exiting the electrodes. The processes also bind lithium ions into new compounds chemicals, so they are no longer available to switch from electricity ode to electrode. These processes will happen regardless of what we do, but are very temperature dependent! Keep the batteries below 30 degrees centigrade and they are very slow. Go beyond 45 degrees centigrade and things speed up considerably! The # 1 public enemy for lithium-ion batteries is heat by far! The calendar life has more to offer and how quickly a LiFePO4 battery will age: the state of charge also has something to do with it. Bad at high temperatures, these batteries really, really don’t like to sit at 0% SOC and very high temperatures!
Also bad, although not quite as bad as 0% SOC, is sitting at 100% SOC and high temperatures for them. Very Low Temperatures As we discussed earlier, you cannot charge LFP batteries below freezing (and the BMS will not allow you to). It turns out that while it can be discharged below freezing, it also has an accelerated effect on aging. Nowhere near as bad as leaving your battery at a high temperature. However, if you are exposing your battery to freezing temperatures, it is better to do so while it is neither charging nor discharging and there is some gas in the tank (though not a full tank). In general, it is better to put these batteries away. a t around 50% – 60% SOC if they need to be stored longer. Molten Battery If you really want to know, what happens when a lithium-ion battery is charged below zero is that metallic lithium is deposited on the negative (carbon) electrode. , which end up puncturing the membrane and shorting out the battery (leading to a spectacular, unscheduled rapid disassembly event as NASA calls it, involving smoke, extreme heat, and most likely flames). Lucky for us this is something the BMS prevents from We move on to cycle life It has become common to get thousands of cycles, even at a full 100% charge-discharge cycle, with lithium-ion batteries There are some things you can do to maximize cycle life.
We talked about how LiFePO4 batteries work – they move lithium ions between electrodes It is important to understand that these are real physical particles, which have a size for them, are torn off one electrode and inserted into the other, each time the battery is charged-discharged This causes damage, particularly to the carbon of the negative electrode. Each time the battery is charged the electrode swells a little and thins again with each discharge. Over time this causes microscopic cracks. it is for this reason that loading a little below 100% will give you more cycles, as will discharging a little above 0%. Also, think of those ions as exerting “pressure,” and the extreme numbers of state of charge exert more pressure, causing chemical reactions that aren’t good for the battery. This is why LFP batteries don’t like being stored away. at 100% SOC, or float charge at (near) 100%. How quickly lithium ions are dragged here and there also has an effect on cycle life. Given the above, this shouldn’t come as a surprise. While LFP batteries are routinely charged and discharged at 1 ° C (i.e. 100 amps for a 100 Ah battery), you will see more cycles from your battery if you limit this to more reasonable values for lead-acid batteries Limit of about 20% of the Ah rating, and adhering to this limit for lithium-ion also has benefits for longer battery life. The last factor to mention is voltage, although this is really the BMS Lithium-ion batteries have a narrow voltage window for loading and unloading. Going outside this window very quickly will result in permanent damage and a possible RUD event (NASA talk, as mentioned before) in the upper area. For LiFePO4 this window is about 8.0V (2.0V per cell) up to 16. 8 Volts (4.2V per cell). The integrated BMS should be careful to keep the battery within these limits.
LFP Take-Home Lessons
Now that we know how lithium-ion batteries work, what they like and dislike, and how they ultimately fail, there are some tips to take away. We have made a small list below. If you’re not going to do anything else, please take note of the first two, they have by far the most effect on the overall time you have to enjoy your Li-ion battery! Paying attention to others will also help, to make the battery last even longer. above, for long and happy LFP battery life, in order of importance, you should pay attention to the following: Keep the battery temperature below 45 degrees centigrade (below 30 degrees if possible) – This is by far the most important! ! Keep charge and discharge currents below 0.5 ° C (preferably 0.2 ° C) Keep battery temperature above 0 degrees Celsius when discharging if possible – This is all located below is nowhere near as important as the first two Do not cycle below 10% – 15% SOC unless Do not float the battery at 100% SOC if possible Do not charge 100% SOC if you have none need That’s it! Now you too can find happiness and a full life with your LiFePO4 batteries!
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