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New LiFePo4 Prismatic Cells sizes 306ah 314ah 320ah and more in 2024

Breaking this is likely the most important news to hit the DIY Solar and Lithium Lifepo4 Battery Off Grid community in 10 years. This really is going to upset the YouTube community apple cart. Especially that guy that lives in Australia who isn’t even Australian.

Currently, 280Ah and 300ah cells are the mainstream in Lifepo4 Batteries, but with the acceleration of technological iteration, the improvement to battery cathode and electrolyte technology in the past few years, over 20 types of high-capacity cells above 300Ah have emerged, these cells will take considerable time to enter the retail and B grade markets, but they are coming in 2024 and 2025. Some of these cells can be purchased now in very large quantity, but for the average joe, building batteries at home DIY style the best mix of value and performance still likes in the 280ah capacity cells over the next few months.

Super Large Capacity LiFePO4 Cells

With the rapid development of the energy storage industry, the market demand for cells continues to outpace supply. Many companies are increasing cell capacity through technological iteration. Cell capacity is growing larger, from 306ah to 314Ah, 320Ah, 340ah and 360ah and then to 500ah 560Ah and 580ah cells

EVE LF560K (628Ah) LiFePO4 Cells

Last year, EVE Energy launched the LF560K battery, adopting cutting-edge Cell to TWh (CTT) technology tailored for TWh-scale energy storage applications. This enables extremely streamlined system integration and dual reduction in costs at both the cell and system levels. Global delivery is expected to commence in Q2 2024.

Keep in mind the DIY community won’t likely see these cells until at least 2025.

EVE LF560K (628Ah) LiFePO4 Cells
EVE LF560K (628Ah) LiFePO4 Cells

Compared to the LF280K battery, the LF560K battery can reduce components like busbars by almost half, whilst improving production efficiency by 30%. Container energy density can be increased by 6.5% allowing for lower costs for customers.

EVE LF560K 628Ah LiFePO4 Cells Data infomation 1

To address the key technological challenges facing the manufacture of ultra-large battery cells, EVE Energy has adopted a “stacking technique” to resolve issues with current collection and manufacturability in the LF560K battery’s electrode and current conductor design. Because the number of tabs per winding is doubled, solving the current collection problem and reducing DC IR by 8%. Prismatic sheet stacking replaces winding, doubling the single electrode sheet length, yields a 3% increase in total cell production .

EVE LF560K 628Ah LiFePO4 Cells Data infomation 2

The LF560K battery represents EVE Energy’s relentless pursuit of innovation and quality, built upon over 21 years of extensive experience in the battery industry and the strong R&D capabilities of its 3,100-member research team.

Currently, the mainstream energy storage cells on the market are 280Ah rectangular aluminum-cased cells. Many manufacturers are also reducing costs for downstream customers by improving cell volumetric density – that is, increasing capacity density per unit volume.

The 560Ah cell essentially doubles the common 280Ah rectangular cell size, equivalent to placing two 280Ah cells side-by-side. This aims to reduce PACK components and achieve cost reduction.

Although the 560Ah cell is not yet EVE Energy’s primary product, it has embarked on the path to commercialization. On February 1 this year, EVE Energy broke ground on its new “60 GWh Power Energy Storage Battery Super Factory” in Jingmen, Hubei, with 10.8 billion RMB investment. This factory will mass-produce the 560Ah energy storage cell. The 560Ah cell is expected to commence global delivery in Q2 2024.

Vision 580Ah LiFePOP4 Cell

On May 16, China’s largest battery exhibition, CIBF 2023, opened in Shenzhen. Thunder Corporation prominently displayed an ultra-high capacity cell.

The 580Ah ultra-large single-cell released by Thunder Corp is the largest capacity single-cell emerged so far globally.

Although the exhibit at CIBF appeared high-profile, it only showcased partial specs. The company claims 10,000 cycle life, 11kg weight per cell, 1856Wh nominal capacity, and 0.5C charge/discharge rate. But details such as packaging technology, mass production timeline, and delivery schedule remain unclear.

With over 10,000 cycle life, the 580Ah cell represents a two-pronged upgrade at both the cell and system levels, providing customers robust safety assurance and performance guarantee. Technologies such as low-expansion anode materials, full tab design, electrode surface treatment, and flexible electrode forming help resolve liquid infiltration challenges for large cells, enabling comprehensive safety protection and high cycle life through heat insulation, diffusion prevention, pressure relief, and more. This will better meet application requirements for grid-scale energy storage, greatly improving system safety, lifespan, and lowering life-cycle electricity costs.

Vision 580Ah LiFePOP4 Cell
Vision 580Ah LiFePOP4 Cell

Currently, there is no universally accepted single-model standard for energy storage cells, and the industry has not yet formed complete standardization. It is believed that with continuous technological breakthroughs and improved designs, more energy storage cell solutions will emerge over time.

Enterprises should pursue R&D across diverse cell models, material systems, and cost schemes. With market validation over time, superior cell designs will become proven, catalyzing new breakthroughs in energy storage cells. This is a crucial premise for the healthy development of the energy storage industry.

CATL 306Ah/314Ah LiFePO4 Cell

CATL New 306Ah 285Ah 280Ah LiFePO4 Cells 1024x768 1

CATL said that the mass production and delivery of 314Ah dedicated electric core for energy storage is another opportunity for the company to lead the development of energy storage system through technological innovation and bring new breakthroughs in the field of energy storage.

CATL 306Ah 285Ah 280Ah LiFePO4 Cells

It is understood that CATL EnerD series products use its energy storage dedicated 314Ah core, and equipped with CTP liquid cooling 3.0 high-efficiency grouping technology, optimizing the grouping structure and conductive connection structure of the core, while adopting a more modular and standardized design in the process of design and manufacturing, to achieve the 20-foot single compartment of the power from 3.354MWh to 5.0MWh, compared with the previous generation of products. Compared to its predecessor, the new EnerD series of liquid-cooled prefabricated energy storage pods saves more than 20% of floor space, reduces the amount of construction work by 15%, and decreases commissioning, operation and maintenance costs by 10%, and also significantly improves energy density and performance.

CALB 305Ah/314Ah LiFePO4 Cells

CALB 305Ah 314Ah LiFePO4 Cells 1024x630 1
CALB 305Ah & 314Ah LiFePO4 Cells
CALB 314Ah LiFePO4 Cell Data Infomation
CALB 314Ah LiFePO4 Cell Data & Infomation

SVOLT 325Ah LiFePO4 Blade Cell

SVOLT 325Ah LiFePO4 Blade Cell
SVOLT 325Ah LiFePO4 Blade Cell

GOTION 300Ah/340Ah LiFePO4 Cell

GOTION 340Ah LiFePO4 Prismatic Battery Cells 1
GOTION 340Ah LiFePO4 Prismatic Battery Cells

REPT 320Ah/340Ah LiFePO4 Cells

REPT 320Ah 340Ah LiFePO4 Cells
REPT 320Ah & 340Ah LiFePO4 Cells

BATTERO TECH 314Ah LiFePO4 Cell

兰钧 BATTERO TECH 314Ah LiFePO4 Cell
BATTERO TECH 314Ah LiFePO4 Cell

Great Power 320Ah LiFePO4 Cell

Great Power 320Ah 280Ah 220Ah 150Ah LiFePO4 Cells

Higee 314Ah/375Ah LiFePO4 Cell

Higee 375Ah LiFePO4 Cell
Higee 375Ah LiFePO4 Cell

ETC 314Ah LiFePO4 Cell

ETC 314Ah LiFePO4 Cell
ETC 314Ah LiFePO4 Cell

HTHIUM 300Ah/314Ah LiFePO4 Cells

海辰 HTHIUM 300Ah LiFePO4 Cell
HTHIUM 300Ah LiFePO4 Cell
海辰 HTHIUM 314Ah LiFePO4 Cell
HTHIUM 314Ah LiFePO4 Cell

Cornex 306Ah/314Ah/320Ah LiFePO4 Cells

楚能 Cornex 314Ah LiFePO4 Cell
Cornex 314Ah LiFePO4 Cell
楚能 Cornex 306Ah LiFePO4 Cell
Cornex 306Ah LiFePO4 Cell

Narada 305Ah LiFePO4 Cell

Narada 305Ah LiFePO4 Cell
Narada 305Ah LiFePO4 Cell

TrinaStorage 306Ah/314Ah LiFePo4 Cells

天合储能 TrinaStorage 314Ah LiFePO4 Cells
TrinaStorage 314Ah LiFePO4 Cells

SUNWODA 314Ah LiFePO4 Cell

SUNWODA 314Ah LiFePO4 Cell
SUNWODA 314Ah LiFePO4 Cell
SUNWODA 314Ah LiFePO4 Cell Data infomation
SUNWODA 314Ah LiFePO4 Cell Data infomation 2
SUNWODA 314Ah LiFePO4 Cell Data & infomation

JEVE 305Ah/360Ah LiFePO4 Cells

JEVE 305Ah 360Ah LiFePO4 Cell
JEVE 305Ah & 360Ah LiFePO4 Cell

COSPOWERS 305Ah LiFePO4 Cell

昆宇电源 COSPOWERS 305Ah LiFePO4 Cell
COSPOWERS 305Ah LiFePO4 Cell

shoto 315Ah LiFePO4 Cell

双登集团 shoto 315Ah LiFePO4 Cell
Shoto 315Ah LiFePO4 Cell

ZENERGY 314Ah LiFePO4 Cell

正力新能 ZENERGY 314Ah LiFePO4 Cell
ZENERGY 314Ah LiFePO4 Cell

Seeking the “Triangle Balance Point”

At the 320Ah capacity level, internal cell temperatures can surpass 800°C, exceeding the decomposition temperature of lithium iron phosphate and posing challenges to cell safety, energy density, manufacturing processes, and more.

Cell R&D also faces the classic ‘impossible trinity’ of high energy density, long cycle life, and high safety. Energy density is a priority consideration in nearly all cell design. Pursuing higher energy density requires thinner membranes and high pressure and areal density electrode materials. On one hand, such extremities make liquid infiltration more difficult, undermining cycling performance. On the other hand, thinner membranes and higher energy density materials also mean poorer safety. There is no avoiding the trade-off between energy density and performance. Prioritizing energy density may jeopardize cycle life and safety. Whereas uncompromising cycle life and safety comes at the cost of lower energy density and weaker competitiveness. Most companies aim for a balanced sweet spot.

Cell manufacturers often tout cycle life figures of 6,000, 8,000, 10,000 even 18,000 based on specific controlled test conditions and model extrapolation. But actual cycle life is lower when cells are packaged into battery packs and deployed in energy storage systems. We expect a lifespan of about 3-18 years depending on the Depth of discharge, C rate, thermal and Battery Management put into place by each individual builder. That is a significant difference, because batteries are not invincible, but LiFePo4 is really versatile.

The 280Ah cells released in 2020 were produced by less than three manufacturers in 2021. Becoming mainstream in energy storage power stations in 2022, failure rate issues can be expected to surge around 2025 after initial installations complete their lifespan. Time will tell.

Safety Depends on Multiple Factors

Larger cells are a double-edged sword – cost reduction and accelerated market growth come with technical challenges and safety concerns. At the system level, safety depends on factors including cell design, thermal propagation isolation, early warning systems, fire prevention systems, and more.

Looking narrowly at the cell perspective, rising manufacturing automation enables producers to strengthen quality control capabilities. Meanwhile, breakthroughs in automated inspection equipment and methodologies screen cell safety before leaving factories.

Advancements in materials such as more thermally/chemically stable membrane systems and additives will also continuously improve battery safety and stability. But from an electrochemical standpoint, absolute safety remains elusive for lithium-ion batteries given inherent risks requiring mitigation through system design, monitoring, emergency response, and other management strategies. Therefore, a systematic approach will define future safety design.

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LiFePo4 B grade EVE 280ah QR codes
EVE letter B meaning

EVE will now engrave the letter B

All Alibaba/Aliexpress sellers will now only be able to supply B grade cells, this information has come directly from EVE themselves. This includes stores such as Shenzhen Qishou Technology Limited made famous in Australia by the Off Grid Garage.
We know that these companies are already looking to replace the QR Codes of the B grade cells, to make them appear as A grade for the market. As they told us directly when we asked.

We have known for a long time that it was likely all cells on Alibaba are B grade or used cells. We just had no good way to prove this.

What we now know is that all cells on Alibaba that are EVE will be marked with the letter B. That stands for a B grade, and if it doesn’t, the QR will have been changed. EVE Energy has assured us, that they do not sell to any of the Alibaba suppliers any A-Grade product for battery storage. To ensure you are receiving A-grade cells you will need to purchase your cells at a higher price, from Lifepo4 Australia or our partners.

We have made the decision to work with both EVE and some Alibaba sellers on the B grade cells, that have been hand-picked to be the better quality of the B grade cells. As we know they can work in certain scenarios, especially for caravans and camping purposes.

We highly recommend anyone choosing their LIFEPO4 cells for home or commercial use buy only A-grade cells. Yes, they are a little more expensive however, the math will work out heavily in your favor over time. When you’re A grade cells are still performing after 1000 cycles, all the way to 6000 cycles as EVE and CATL claim their A grade cells can achieve.

We also know that all the CATL cells on Alibaba and Aliexpress are either used, or B grade, as CATL does not sell A grade cells to any of the battery manufacturers on Alibaba and Aliexpress.

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EVE vs CATL

Both EVE and CATL are professional LFP Prismatic manufacturers in China.
CATL is the world’s largest battery manufacturer, and EVE is inside the TOP 10.
Both companies work with car manufacturers, like Tesla, Geely, and Dongfeng Motors.

Both of these companies are poised for huge growth in the coming decade.

Both of these manufacturers have produced slightly different battery compositions to cater for either a high C rate discharge or a longer life low C rate prismatic cell. The LF280K from EVE is now widely respected and known to be of high quality.

CATL however, is not selling cells directly to the public, so all CATL cells are sold on the grey market, on places such as Alibaba, and Made in China. Many of these sellers, do sell B-grade cells, so you are taking a huge risk to purchase from these marketplaces.

EVE does allow the purchase of LFP cells directly to the public however, most people choose not to purchase from EVE because they don’t understand that a huge percentage (98%) of Alibaba and Aliexpress cells are actually B grade cells. They also have very complicated shipping procedures which are very difficult for the average person wot work with.

EVE Logo 610x2861 1 wpp1630410453474
Model
Voltage
Capacity
Height
Length
Width
Weight (g)
LF50K
3.2v
50ah
185
135.3
29.3
1395
LF80
3.2v
80ah
170.5
130.3
36.7
1630
LF90K
3.2v
90ah
200.5
130.3
36.7
1970
LF100MA
3.2v
100ah
118.5
160
49.9
1920
LF105
3.2v
105ah
200.5
130.3
36.7
1980
LF173
3.2v
173ah
207
174
41
3250
LF230
3.2v
230ah
207.3
174
53.9
4110
LF280
3.2v
280ah
200
173.7
72
5220
LF280N
3.2v
280ah
200
173.7
72
5300
LF280K
3.2v
280ah
204.6
173.7
72
5420
LF304
3.2v
304ah
208.8
173.5
72
5490
1200px Contemporary Amperex Technology logo
Model
Voltage
Capacity
Height
Length
Width
Weight (g)
CB50
3.2v
50ah
135
175
30
1390
CB60
3.2v
60ah
220
135
29
1900
CB86
3.2v
86ah
133
173
47
2160
CB100
3.2v
100ah
170
200
34
2270
CB105
3.2v
105ah
167
200
34
2260
CB120
3.2v
120ah
170
174
48
2860
CB140
3.2v
140ah
171
200
46
3200
CB176
3.2v
176ah
205
174
54
3800
CB202
3.2v
202ah
201
174
54
4120
CB271
3.2v
271ah
207.2
174
71.7
5470
CB280
3.2v
280ah
207.2
174
71.7
5340
CB310
3.2v
310ah
208
174.5
72.5
5800

How to tell them apart visually

Let’s begin with the most common cell the 280ah capacity cells. The first thing you will notice is both have the QR code in the same location. However, the EVE cell has oval-shaped terminals and the CATL has circular.
Genuine EVE cells will also state the cell model. eg LF280 or LF280K

CATL 280AH

EVE LF280K

catl280AH 2022 1
LF280K QR
eve-lf280k-qr
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LIFEPO4 QR VENDOR CODES

According to the rules of QR code parsing, we know that the first three characters represent the vendor code.

How to Quickly Identify Fake Batteries Part 3 QR code parsing

Many customers emailed us asking if we have a list of vendor codes. Because there are two cases that need to know the vendor code.

1, You do not know the manufacturer of the LiFePO4 battery cell you are using.

2, You want to confirm whether the LiFePO4 battery cell you received is the one you are targeting.

Unfortunately, there is no official list of LiFePO4 battery cell vendor code so far.

We have maintained the following vendor code list based on our past experience, and hope it can help you identify the manufacturer of the battery cell.

LiFePO4 Battery Cell Vendor Code List

Manufacturer
Vendor Code
CATL
001
EVE
02Y
EVE Power
04Q
REPT
081
Lishen
08B
Ganfeng
0AL
CALB
0B5

Although this list does not cover all, but most of the popular LiFePO4 battery cell manufacturers on the market are on the list.

So you can identify which manufacturer your battery cell comes from based on the first 3 characters of the QR code on your LiFePO4 battery cell.

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LIFEPO4 SOC and everything else you need to know!

LiFePo4 SOC

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.

LiFePo4 cycles
LiFePo4 types

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.

JBD 200amp 12v BMS
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!

This image has an empty alt attribute; its file name is BSLBATT-12V-100AH.jpg

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?

battery gif lim v04

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

320 501 201907301354071

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
Lifepo4 Soc

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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