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Advantages of LiFePO4 Batteries

Optimise your Stationary Power by using LiFePO4

Lithium Iron Phosphate Cells (LiFePO4) – No one can afford to be outside of this revolution!

It is not a case of LiFePO4 being affordable, it is a case of can one afford to use lead acid? The life cycle cost of LiFePO4 cells is a quarter of lead acid batteries. The upfront costs for a pack vary from similar to double depending on the application, but one must consider that in 3 to 6 years’ time the lead-acid batteries must be replaced and the LiFePO4 cells will last 13 to 20 years depending on the application and pack design.

LiFePO4 cells have revolutionised the potential and life cycle cost of operating battery-based power systems. These cells have a cycle life 10 times that of typical deep cycle lead-acid batteries. They only cost approximately 50% more to purchase upfront, however, the saving on life-cycle cost is substantial.

LiFePO4 cells are available in a wide range of sizes to accommodate loads of a few amps to over 1000 amps. They can deliver sustained high power without excessive heat generation. There are no gases released and LiFePO4 cells are also thermally stable. They can be charged repeatedly to full capacity in less than 60 minutes with no appreciable loss in performance.

Backup and Off Grid Battery Packs Using Superior Lithium Iron Phosphate (LiFePO4) Cells – the next Generation of Energy Storage

By:Antony John English
Co-founder Freedom Won Pty Ltd

Lithium Iron Phosphate cells, or LiFePO4 for short, are now dominating the alternate energy storage sphere amongst the more discerning designers and customers in the more advanced markets including Europe, Australia and South Africa.
Freedom Won has been using these cells in electric vehicles since 2010 and in stationary storage since 2014.
Freedom Won provides competitive prices made possible by high volume manufacturing in South Africa and guarantees market leading technical backup and design assistance. Freedom Won has the market leading battery warranty of 10 years with no fine print or diminishing value spurred by our confidence gained from our own test programme in electric vehicles, which is far more demanding on the batteries than stationary power systems. The expected life in off grid systems is more than 15 years, and more than 20 years in grid connected back up installations with occasional cycling. The end of life is defined by when the cells contain 60% of their Beginning of Life (BoL) capacity. The capacity deterioration over time is linear (the deterioration does not become substantially more rapid with extended use), and the cells could therefore be used for even longer periods if a lower end of life capacity is acceptable.
The initial cost of installing a LiFePO4 system as compared to Lead batteries is only marginally higher since the 2018 price decreases in the Freedom Won range. For smaller batteries up to 10kWh this premium is about 40% but for batteries larger than 100kWh this premium is only about 10%.
These premiums in initial cost are dramatically overshadowed by the savings in the total life cycle cost, calculated as a cost per kWh delivered by the battery pack during its lifetime. The lifetime cost per kWh can be as low as 25% of the cost of typical lead acid deep cycle batteries. The main reason for this is that the cells offer up to 10 times the number of cycles than your average deep cycle lead battery and as much as 5 times that of the more robust single cell flooded lead acid types.
Another top benefit to the customer is the far greater efficiency of the LiFePO4 technology, which is typically better than 98%. A typical efficiency for lead batteries is 65%, although this can be as low as 55% in a house PV system where the Depth of Discharge (DoD) is limited to 20% as a measure to lengthen the life of the lead acid cells. In a grid connected back up scenario this high efficiency results in significant energy savings when recharging the batteries, and in a Photo Voltaic (PV) installation it enables a reduction of the size of the array by as much as 30% with the same usable energy.
The advantages of LiFePO4 cells over lead cells are extensive so a full elaboration is not included in this article. A summary is however provided in the table below, and further questions posed to Freedom Won will be welcomed.

Table: Summary of Benefits of Using LiFePO4 Cells in Stationary Power Applications

Comparison Aspect Lead Acid LiFePO4
Cycle Life (50% DoD with 70% remaining capacity, 30 deg C ambient temperature) 500 to 1300 cycles depending on manufacturer and model More than 7000 cycles
Calendar Life Average (poor in high temperature or partial/full discharge condition or infrequent cycling) Excellent – no sulphation, partial charge storage is no problem, regular cycling is not required, heat tolerant
Charge – discharge (round trip) efficiency [%] 60-70% typical depending on current. Typically rated capacity is based on 10 hour discharge (C10) 96%, consistent throughout current range. Rated capacity is based on 20 minute discharge (3C), a one hour or longer discharge will actually give 10% more than the rated capacity.
Temperature resilience Poor – temperatures above 25 deg C significantly reduce the calendar life Excellent – ambient temperatures up to 45 deg C will not affect the life of the cell at all.
Up Front Cost Cheaper 10 to 50% more expensive up front than Lead Acid depending on what lead acid cells are used for comparison and the size of the battery – the Lithium premium on a larger Freedom Lite battery is lower.
Life Cycle Cost per kWh R3.00 (USD0,21) to R6 (USD0,41) depending on battery type and model R1,20 (USD0,08) (approx.)
Quick Charge Time Typically should not be done in less than 5 hours 2 hour standard, 45 min quick
Discharge Current Higher discharge than C10 (10 hours), or 0.1xC rating causes substantial loss in efficiency and affects life C1 (one hour discharge) is standard, higher currents are also acceptable up to 3C (3 x Ah rating) continuous with negligible loss in efficiency and cell life
Gravimetric Energy Density Poor Weigh 3 to 4 times less – reduced transport costs and installation effort.

Volumetric density more than 2 times higher – less than half the space required

Pack Capacity Loss of 30% in heat (70% pack efficiency) means pack must be larger to meet a specific output objective

Max practical DoD is 50%, which requires a larger pack to stay above this DoD to prevent rapid life deterioration

Pack can be sized to 50% of the “rated” capacity of a lead acid pack because of 98% efficiency and ability to discharge on regular occasion to 90% DoD with negligible effect on life reduction
Charging Energy Source Size The charging energy source must provide an additional 30 to 40% energy to overcome the inefficiency of the pack at substantial cost Only about 2% of the energy is lost to heat – big savings in charging energy and capital on PV installations etc

When sizing a LiFePO4 pack, the rating of the cells cannot be compared to a typical lead acid rating without making some adjustments. Owing to the much higher efficiency and the ability to discharge more deeply without rapid capacity deterioration over time means that a LiFePO4 can be sized to about 50% of the lead battery in terms of Ampere hours. This factor originates simply from the fact that only 65% of the rated total energy is available from a lead acid battery in most high power backup applications, whilst 100% of the rated energy is available from LiFePO4 cells.

Because it is practical to use a lower DoD in LiFePO4 cells and still achieve an excellent cycle life the designer can reduce the LiFePO4 pack size and still provide superior performance over a lead battery pack. A typical scenario could be 50% DoD for a lead acid pack compared to 70% DoD for a LiFePO4 pack. This ultimately makes the LiFEPO4 pack energy capacity (kWh) rating 50% of the lead acid rating.

LiFePO4 cells maintain their rated nominal voltage for about 95% of the discharge, whilst a lead cell voltage drops continuously. When working out the Wh of a lead 12V battery one must use about 11.4V for the average voltage under load (1,9V per cell). The nominal voltage for LiFePO4 is 3.2V per cell or 52V for a typical “48V” system.

An example comparing a 200Ah LiFePO4 pack to a 400Ah lead pack is included in the below table. The theoretical energy capacity for the lead battery is reduced to 85% of the rated capacity to replicate a real world discharge scenario vs the manufacturer’s 10 hour constant current test regime used for the nameplate Ah rating. The usable capacities are adjusted to be in line with the typical DoD expected in the design of 50% and 70% for the lead and lithium examples respectively.  The LiFePO4 pack costs only 40% more than the Lead battery, however, after taking into account the cycle life and the kWh produced in the lifetime of the packs it is clear that LiFePO4 costs only 22% of the Lead batteries used in this example.

Table: Comparison Example of Lead Battery vs. LiFePO4

Lead Acid   LiFePO4
8 200Ah Lead Acid/Gel 16  units of Sinopoly SP-LFP200AHA (Freedom Lite 20/14)
4 Batteries (units) in Series 16 cells in each string
2 Strings 1 Strings
200 Ah Nameplate Capacity 200 Ah Cell Nameplate Capacity
200 Ah each @ 10hr rate 220 Ah at 3 hour rate (one cell per unit)
12 V per battery nameplate 3,4 V per cell nameplate
11,4 V per battery during discharge 3,2 V per cell during discharge
400 Ah total pack 220 Ah total pack
48 V rated total 54 V rated total
45,6 V nom of pack during discharge 51,2 V nom of pack during discharge
18240 Wh @ 10 hr discharge (260AhX44V) 11264 Wh available and rated for 100% DOD
85% Derating of 10hr Capacity 100% No derating required
15504 Wh available for 100% DOD 11264 Wh available and rated for 100% DOD
7752 Wh available for 50% DOD 7885 Wh available for 70% DOD
50% Percent of LiFePO4 pack rated capacity required to match Lead Acid
 R          6 000 Unit Retail Cost Excl VAT (one 12V battery)  n/a
 R       48 000 Pack Upfront Cost  R        67 000 Retail Cost Excl VAT (Complete Freedom Lite 20/14 battery)
1,40 ratio for upfront cost
950 Cycle life at 60% of BoL Capacity 6000 Cycle life at 60% of BoL Capacity
2,6 Life in years – 365 cycles per year 16,4 Life in years – 365 cycles per year
7364,4 Kwh in lifetime 47308,8 Kwh in lifetime
 R            6,52 cost per kWh  R            1,42 cost per kWh
22% Cost of LiFePO4 life cycle compared to Lead Acid

The batteries supplied by Freedom Won are available in various sizes. The Lite 15/11 is the most popular because it is ideal for a typical 3 bedroom house. They can be connected in parallel if future upgrades in capacity are required. The LiFePO4 pack in the Freedom Lite is connected to a Battery Management System (BMS) that is able to monitor the voltage of each cell and prevent any cell from exceeding the upper and lower limits. The BMS must also balance the cells to ensure that the pack can perform at its best. LiFePO4 cells do not naturally balance themselves. Freedom Won supplies the Lite with the BMS configured for each application.

For further information, assistance and sales of LiFePO4 cells please contact sales or enquiries at Freedom Won Pty Ltd via the website www.freedomwon.co.za.

About

Long Life High-Performance Energy

The Freedom Lite Home and Freedom Lite Business range from Freedom Won offers the long overdue next-generation energy storage with a quantum increase in service life and operational efficiency at a fraction of the lifecycle cost compared to other energy storage options.

Compact, Integrated and Attractive

The Freedom Lite Home range covers the varying needs of homeowners and even small business premises with models ranging from the Freedom Lite Home 5/4 to the largest 30/21. These models are wall mounted offering the ultimate in space saving. All models are integrated with the necessary Battery Management System (BMS) and control circuitry to protect the pack and interface with the separately supplied external inverter/charger unit – lithium cells cannot be operated without a BMS. The standard Home enclosure is powder coated with white sides and face.

Control Interface for compatible Inverter/Chargers

The BMS provides digital potential free contacts for independent control of the inverter load and the charge from the main charger and solar charge controller through a multi-pin plug on the side of the module, which also includes pins for voltage sense and charge current control for compatible chargers. The BMS is fully configured prior to delivery.

Power Interface

Positive and negative studs are provided for connecting the 48V DC cables to the inverter and solar charge controller. The DC circuit is protected with a shunt trip circuit breaker.

Facts

Lithium Iron Phosphate (Lite Home) batteries have several advantages over conventional lead-acid batteries:

High energy density: more energy with less weight High charge currents (shortens the charge period) High discharge currents (enabling for example electrical cooking on a small battery bank) Long battery life (up to six times the battery life of a conventional battery) High efficiency between charging and discharging (very little energy loss due to heat development) Higher continuous power available

Rugged

A lead-acid battery can fail prematurely due to sulphation if it is left partially charged, fully discharged, or rarely fully charged for long periods of time. A Lithium Iron Phosphate battery does not need to be fully charged, has a wide operating temperature range and excellent cycling performance. They are, therefore, the battery for very demanding applications.

Efficient

The typical energy efficiency (energy that can be taken out of the battery compared to the energy required to re-charge) for lead acid batteries is ~ 70%. For a LifePO4 battery, it is ~ 92% The final 20% charge for a lead-acid battery is particularly inefficient with efficiencies of ~ 50% and can take a very long time for the battery to become completely charged. In contrast, a LifePO4 battery can still achieve 92% efficiency and so can be fully charged more quickly and using less energy.

Size & Weight

LifePO4 batteries save up to 70% in space and 70% in weight compared to lead-acid.

Expensive?

Lithium Iron Phosphate batteries are expensive when compared to lead-acid, but this is compensated for by longer life, size or weight considerations, superior reliability & efficiency.

Battery Management System

It is vital that the correct battery management system (BMS) is used to control the battery charging. This is important to actively balance the individual cells that make up the battery and prevent under or overvoltage which can otherwise destroy the battery.

backup

Backup

Eliminate grid outages from your home, business or factory by installing a super efficient and long life Lithium battery and inverter system from Freedom Won. We provide backup energy storage solutions for any application from 2.5kWh to 5000kWh or more, using long life high performance Lithium batteries.

Starting From (incl VAT)
R 86 292.30
Financed over 60 months:
R 2183.83 per month

Package Includes:
Freedom Lite Home 5/4
3kVA Inverter
Installation and Delivery incl materials
10 Year Warranty

hybrid

Hybrid

Eliminate grid outages AND reduce your Utility consumption with a long life Lithium battery and Solar Power and save bundles of money. We provide hybrid energy storage solutions for any application from 2.5 to 100 000kWh or more, using long life high performance Lithium batteries.

Starting From (incl VAT)
R 145 914.34
Financed over 60 months:
R 3707.44 per month

Package Includes:
Freedom Lite Home 5/4
Premium Brand 3kVA Inverter
PV Panels 3kWp
Premium Brand Solar Charge Controller
Installation and Delivery incl material

solar

Off Grid

Say goodbye to utility troubles for ever, or avoid initial costly utility infrastructure and run your own off grid Lithium battery based solar power plant on renewable energy with massive long term cost savings. We provide off grid energy storage solutions for any application from 2.5kWh to 5000kWh or more, using long life high performance Lithium batteries.

Starting From (incl VAT)
R 313 065.66
Financed over 60 months:
Deposit R 63 065.66
R 6373.75 per month

Package Includes:
Freedom Lite Home 20/14
Premium Brand 5kVA Inverter
PV Panels 6kWp
Premium Brand Solar Charge Controller
Installation and Delivery incl materials

custom

Special Purpose

Freedom Won offers lithium battery solutions for many special purpose applications. Offerings include lithium batteries for forklifts, golf carts, electric golf caddies, UPS as well as wide range of 12V lithium batteries ( 7.5Ah up to 200Ah). There is nothing else on the market that can come close to competing with Freedom Won products on true life cycle cost and warranty .

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