Contact Us
Tel: +86-755-25629920
Fax: +86-755-25629925
Mob: +8613828897550
E-mail: sales@himaxelectronics.com
Address: Building C, Huaming Industrial Park, Huaming Road, Dalang, Longhua, Shenzhen China
Home > Knowledge > Content
Advantages of LiFePO4 Batteries
Mar 30, 2018

Advantages of LiFePO4 Batteries

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 revolutionized 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.

LiFePO4 Batteries vs Lead Acid

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

 图片1.png

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

Lithium Iron Phosphate cells, or LiFePO4 for short, are beginning to dominate the alternate energy storage sphere amongst the more discerning designers and customers in Europe and some other parts of the world. LiFePO4 cells has been using in electric vehicles and companies are now also providing this superior technology for stationary power applications or all sizes.

The initial higher cost of installing a LiFePO4 system as compared to Lead batteries is 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. Even Lead Crystal batteries cannot compete on life cycle cost. 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 types. This is especially apparent in cases of high current discharge and charging scenarios, further contrasted by high ambient temperatures, both of which are not suitable for lead batteries.

Another top benefit to the customer is the far greater efficiency of the LiFePO4 cell, which is typically better than 96%. A typical efficiency for lead batteries is 65%, although empirical data has demonstrated 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 tied back up scenario this 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.


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

Comparison Aspect

Lead Acid

LiFePO4

Cycle Life (50% DOD with 80% remaining capacity, 30 deg C ambient temperature)

500 to 1300 cycles depending on manufacturer and model

Up to 5000 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 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

20 to 50% more expensive up front than Lead Acid depending on what lead acid cells are used for comparison

Quick Charge Time

Typically should not be done in less than 5 hours

1 hour standard, 30 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 60% of the “rated” capacity of a lead acid pack because of 96% efficiency and ability to discharge on regular occasion to 80% DOD with much lower 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 4% of the energy is lost to heat – big savings in charging energy and capital on PV installations etc