Tag Archive for: lithium ion battery

solar battery bank

Li-ion Battery Basic Knowledge for Solar Street light Battery Pack

(1) Composition of Li-ion battery

Li-ion battery is mainly composed of two parts: battery cell and a protection board PCM (power battery is generally called battery management system BMS). The Li-ion Battery cell is the heart of Li-ion battery, and the management system is equivalent to the brain of a Li-ion battery.

The core is mainly composed of positive electrode material, negative electrode material, an electrolyte, a diaphragm, and a shell. The protection plate is mainly composed of protection chip (or management chip), MOS tube, resistance, capacitance, and a PCB board.

(2) Advantages and disadvantages of Li-ion battery

Li-ion battery has many advantages, such as high voltage platform, high energy density (lightweight, small volume), long service life, and environmental protection.

The disadvantage of lithium battery is that the price is relatively high, the temperature range is relatively narrow, and there are certain security risks (need to add protection system).

Comparison parameters of various batteries Lead-acid battery Nickel-cadmium battery
(Ni-Cd)
Nickel metal hydride battery
(Ni-MH)
lithium battery
Nominal voltage

(V)

2 1.2 1.2 3.2/3.6/3.7
Weight energy density

(WH / kg)

25~30 40~45 60~65 120~200
Volume energy density

(WH / L)

65~80 150~180 300~350 350~400
Optimum working temperature (℃) -40~70 -20~60 -20~45 0~45
Environment friendly lead pollution Cadmium

pollution

/ /
Recycle

(times)

200~300 500 1000 500~1500
Cost

(RMB/Wh)

0.6~1.0 2.0~2.6 2.5~3.8 2.0~3.5
Charger cost Low
(Stabilizedvoltage source)
General
(Constant current source)
General

(Constant current source)

High
(Constant current and pressure)

(3) Li-ion Battery classification

Li-ion battery

Lithium batteries can be divided into two categories: disposable non-rechargeable batteries and rechargeable batteries (also known as a battery).

Non-rechargeable batteries such as lithium manganese dioxide batteries, lithium sulfimide batteries.

Rechargeable batteries can be divided into the following categories according to different situations.

  1. According to appearance: square lithium battery (such as ordinary mobile phone battery) and cylindrical lithium battery (such as 18650 of electric tools);
  2. According to the outsourcing materials: aluminum shell lithium battery, steel shell lithium battery, and soft bag battery.
  3. According to the cathode materials, lithium cobaltic acid (LiCoO2), lithium manganate (LiMn2O4), lithium ternary (linixcoymnzo2), and lithium iron phosphate (LiFePO4);
  4. According to the state of electrolyte: lithium-ion battery (LIB) and polymer battery (PLB);
  5. According to usage: general battery and power battery.
  6. According to performance characteristics: high capacity battery, high-rate battery, high-temperature battery, low-temperature battery, etc.

(4) Explanation of common terms

  1. Capacity

It refers to the amount of electricity that can be obtained from lithium battery under certain discharge conditions.

We know in high school physics that the formula of electric quantity is q = I * t, the unit is Coulomb, and the unit of battery capacity is specified as Ah (ampere-hour) or mAh (milliampere-hour). This means that a battery of 1Ah can be discharged for 1 hour with a current of 1A when it is fully charged.

In the past, the battery of Nokia’s old mobile phone (like bl-5c) was generally 500mah. Now, the current smartphone battery is 800-1900mah, the battery of the electric bicycle is generally 10-20ah, and the battery of the electric vehicles is generally 20-200ah.

  1. Charge rate / discharge rate

It indicates how much current is used for charging and discharging. It is generally calculated by the multiple of the nominal capacity of the battery, which is generally called “several C”.

For a battery with a capacity of 1500mah, 1c = 1500mah is specified. If discharging at 2c,it means discharging at 3000ma current. Charging and discharging at 0.1c means it is charging and discharging at 150mA current.

  1. Voltage (OCV: open circuit voltage)

The battery voltage generally refers to the nominal voltage of lithium battery (also known as rated voltage). The nominal voltage of ordinary lithium battery is generally 3.7V, we also call its voltage platform 3.7V. When we say voltage, we generally mean the open-circuit voltage of the battery.

When the capacity of the battery is 20-80%, the voltage is concentrated around 3.7V (3.6-3.9v), when the capacity is too high or too low, and the voltage changes greatly.

  1. Energy/power

When the battery is discharged according to a certain standard, the energy (E) that the battery can discharge is Wh (watt-hour) or kWh (kilowatt-hour), and 1kwh = 1-kilowatt hour.

The physics book has a basic concept, e = u * I * t, which is also equal to the battery voltage times the battery capacity.

The formula of power is p = u * I = E / T, which represents the energy that can be released per unit time. The unit is w (W) or kW (kW).

For a battery with a capacity of 1500mah, the nominal voltage is generally 3.7V, so the corresponding energy is 5.55wh.

  1. Resistance

Since charging and discharging cannot be equivalent to an ideal power supply because of certain internal resistance. The internal resistance consumes energy. The smaller the internal resistance, the better it is.

The unit of battery internal resistance is milliohm (m Ω).

Generally, the internal resistance of a battery consists of ohmic internal resistance and a polarized internal resistance. The size of the internal resistance is affected by the material, manufacturing process and the structure of the battery.

  1. Cycle life

Once the battery is charged and discharged, it is called a cycle, and the cycle life is an important indicator to measure the battery life performance.

According to IEC standard, the lithium battery of the mobile phone shall be discharged to 3.0V at 0.2C and charged to 4.2V at 1C. The battery capacity shall be maintained above 60% of the initial capacity after 500 cycles. In other words, the cycle life of lithium battery is 500 times.

According to the national standard, the capacity shall remain at 70% of the initial capacity after 300 cycles.

If the battery capacity is less than 60% of the initial capacity, it is generally considered to be scrapped.

  1. DOD: depth of discharger

It is defined as the percentage of the rated capacity released by the battery.

Generally, the deeper the discharge depth is, the shorter the battery life is.

  1. Cut off voltage

The termination voltage is divided into charging termination voltage and discharging termination voltage, that is, the voltage at which the battery cannot continue to be charged or discharged. If the battery is continued to be  charged or discharged at the termination voltage, the battery life is going to be greatly affected.

The charge-discharge termination voltage of lithium battery is 4.2V and 3.0V respectively.

It is strictly prohibited to charge or discharge lithium batteries beyond the termination voltage.

  1. Self-discharge

It refers to the rate of decrease in capacity durisolar batteriesng storage, expressed as the percentage of capacity decrease per unit time.

The self-discharge rate of general lithium battery is 2% ~ 9% / month.

  1.   SOC (State of Charge)

This refers to the percentage of the remaining power of the battery and the total power that can be discharged, 0 ~ 100%. Reflect the remaining battery power.

 

(5) Li-ion Battery naming rules

Different battery manufacturers have different naming rules, but we all follow a unified standard for general batteries. The size of the battery can be known according to the name of the battery

According to IEC61960, the rules for cylindrical and square batteries are as follows:

  1. Cylindrical battery, 3 letters followed by 5 numbers,

Three letters, the first letter represents the negative electrode material, I means there is a  built-in lithium-ion, L represents the lithium metal or lithium alloy electrode. The second letter indicates the positive electrode material, C indicates cobalt, n indicates nickel, m indicates manganese, and V indicates vanadium. The third letter is R for a cylinder.5 digits, the first 2 digits represent the diameter, the last 3 digits represent the height, all in mm.

  1. Square battery, 6 digits after 3 letters,

Three letters. The first two letters have the same meaning as a cylinder. The last one is p, which means square.

There are six digits, the first two digits indicate the thickness, the middle indicates the width, the last two indicate the height (length), the unit is also mm.

For example, ICR 18650 is a universal 18650 cylindrical battery with a diameter of 18mm and a height of 65mm;

ICP 053353 is a square battery with a thickness of 5mm, a width of 33mm, and a height (length) of 53mm.

(6) Li-ion Battery technology

There are some differences in the process flow of different batteries and different manufacturers, and the detailed process flow will be very complex. The basic process flow, the process flow of cell manufacturing and the process flow of pack manufacturing are listed below.

The production process of an electric cell mainly includes pole piece manufacturing, electric cell manufacturing, battery assembly, liquid injection, chemical formation, separation, and other processes.

From batching to winding, the positive and negative electrodes are made in different workshops at the same time. After the positive and negative electrodes are made, the subsequent processes are done together. Different QA links of quality inspection will be inserted in the middle.

(7) Group and series-parallel connection of Li-ion Battery

In different fields, the requirements for batteries are different. The system has some special requirements for voltage, capacity, internal resistance, etc. often a single battery cannot meet the requirements, it needs to be connected in series and parallel to supply power to the outside.

The performance of batteries in series and in parallel is determined by the performance of the worst battery, which is often referred to as the “barrel principle”. Therefore, the most important point of battery grouping is the consistency of battery performance parameters.

For example, a notebook, electric bicycle, electric vehicle, energy storage system, etc. all need to consider the series and parallel connection of the batteries to form a battery pack.

The battery voltage of the notebook is generally 11.1v or 14.8V, mainly 18650 batteries, so it is generally 2 series and 3 parallel or 2 series and 4 parallel.

Apple iPad is three polymer batteries connected in parallel, with a capacity of about 25wh.

The electric bicycle and electric motorcycle systems are generally 24V, 36V, 48V, 60V, and 72V systems. See the following table for specific group conditions (s represents a series connection).

Pure electric vehicles and hybrid electric vehicles (EV / PHEV) have a higher voltage, about 250 ~ 500V, and the maximum voltage will be more than 150 knots connected in series.

In addition, there are many things to be considered in the grouping of batteries in a series-parallel connection, such as the consistency of the battery voltage platform, the consistency of the battery capacity, the consistency of the internal resistance of the battery, etc.

The consistency of battery parameters after a series-parallel connection has a great influence on the performance and life of the battery.

Battery pack voltage Lithium manganate / ternary lithium Lithium iron phosphate
12V 4S 4S
18V 5S 6S
24V 7S 8S
36V 10S 12S
48V 13S 15S/16S
60V 16S 19S
64V 18S 20S
72V 20S 23S

 8) Comparison of various power batteries

Power battery is mainly considered in terms of its application, mainly used in electric vehicles, electric bicycles, electric tools and so on.

The power battery is different from an ordinary battery, but it has some special characteristics

  1. Series and parallel connection of batteries
  2. The battery has a larger capacity
  3. The discharge rate of the battery is high (hybrid power and electric tools)
  4. The battery has higher safety requirements
  5. The battery has a wide operating temperature range
  6. The service life of the battery is long, generally 5-10 years

Due to the particularity of the power battery, there are some differences in its process and materials. According to the situation of positive electrode materials, it is mainly divided into lithium manganate (LiMn2O4), lithium ternary (linixcoymnzo2), lithium iron phosphate (LiFePO4), etc. its voltage platform, energy density, price, safety, etc. all have certain differences. See the comparison in the table below for details:

(lithium cobaltite is rarely used as power battery due to its poor stability and high price, which is listed and compared in the table below)

Items Specification cobalt acid lithium Ternary lithium Manganate lithium Lithium iron phosphate
1 tapped density(g/cm3) 2.8~3.0 2.0~2.3 2.2~2.4 1.0~1.4
2 Specific surface area(m2/g) 0.4~0.6 0.2~0.4 0.4~0.8 12~20
3 Capacity density(Ah/kg) 135~140 155~165 100~115 130~140
4 Voltage platform(V) 3.7 3.6 3.6 3.2
5 Recycle times >300 >800 >500 >2000
6 transition metal Poor Poor Rich  Much rich
7 Material cost Very high High Low Low
8 Environment friendly Cobalt Containing nickel and cobalt /    /
9 Safety Poor General Good Excellent
10 Application Small battery Small battery, Small power battery Power battery Power Battery, Super capacity power supply

(9) Lithium battery model

In terms of electrical characteristics, the internal resistance of the battery is not completely equivalent to a resistor. For details, please refer to the foreign PNGV equivalent circuit model. As shown in the figure below.

The internal resistance of the battery is mainly composed of ohmic resistance R0 and polarization resistance R1, where C1 is the polarization capacitance.

There are two main test methods for battery internal resistance measurement in the industry. The DC discharge method and the AC injection method, which cannot be measured by the ordinary method of measuring resistance, but can only be measures by the special internal resistance measuring instrument.

The internal resistance of the battery is an important parameter reflecting the performance and life of the battery. When the cycle life of the battery approaches, the internal resistance of the battery increases sharply. The relationship between the number of cycles and the internal resistance is shown in the figure below.

10) Electrical characteristics and key parameters of Li-ion Battery

  1. The charge-discharge curve of the battery

The charge and discharge curve of lithium battery refers to the relationship curve between battery capacity and the open-circuit voltage. According to the discharge curve, the battery’s power can be roughly estimated, as shown in the figure below.

The charge-discharge curve of lithium battery is not only related to the charging and discharging current but also to the temperature. As shown in the figure below.

  1. Key parameters of the battery

Due to its own characteristics, lithium battery cannot be overcharged, over-discharge, over-current, or over temperature. Therefore, considering safety and battery life, the battery should be properly protected. There are several parameters that are often encountered, and they are listed in parallel. There is little difference in voltage between different manufacturers. However, there will be some differences between batteries with different operating temperatures, different discharge rates or different manufacturers.

Comparison item Manganate lithium/Ternary Lithium Lithium iron phosphate
Voltage 3.7V/3.6V 3.2V
Cut-off charge voltage 4.2V 3.6V
Discharge Cut-off Voltage 3.0V 2.0V
Operation temperature -20~60℃ -10~65℃
Maximum discharge rate 3~10C 3~10C

11) Li-ion Battery protection and management requirements and systems

Due to the characteristics of lithium batteries, it is necessary to add a battery protection board (PCM) or a battery management system (BMS). Batteries without a protection board or management system are prohibited to use, and there will be huge safety risks. Safety is always the first priority for battery systems.

If the battery is not well protected or managed, there may be a risk of a shortened life, damage, or explosion.

The PCM (power circuit module) is mainly used in consumer products such as mobile phones and notebooks.

Battery management system (BMS) is mainly used in power batteries, such as electric vehicles, electric bicycles, energy storage, and other large-scale systems.

The main functions of PCM include OVP, UVP, OTP, OCP, etc. In case of any abnormality, the system will cut off automatically to ensure the safety of the system.

The battery protection system technology is very mature, there are many related board factories, mainly concentrated in South China. And there are special IC manufacturers providing special lithium battery protection chips. This piece is relatively mature, and there are many mature protection IC chips in China.

In addition to the basic protection functions of the protection system, the main functions of the battery management system (BMS) include battery voltage, temperature, and current measurement, energy balance, SOC calculation and display, abnormal alarm, charge and discharge management, communication, etc. Some BMS systems also integrate heat management, battery heating, battery health status (soh) analysis, insulation resistance measurement, etc.

Introduction and analysis of BMS function:

  1. Battery protection is similar to PCM, which includes overcharge, over-discharge, over-temperature, over current, and short circuit protection. Like ordinary lithium manganese battery and ternary lithium battery, once the voltage of any battery exceeds 4.2V or the voltage of any battery falls lower than 3.0V, the system will automatically cut off the charging or discharging circuit. If the temperature of the battery exceeds the working temperature of the battery or the current is greater than the discharge current of the battery, the system will automatically cut off the current path to ensure the safety of the battery and the system.
  2. Energy balance of the whole battery pack after working for a certain period of time will show great differences that could be, due to having many batteries in series, due to the inconsistency of the cell itself, the inconsistency of working temperature or other reasons., This has a great impact on the life of the battery and the use of the system. Energy balance is to make up for the differences between individual cells to do some active or passive charge or discharge management to ensure battery consistency and prolong battery life.

There are two kinds of methods in the industry: passive equalization and active equalization. Passive equalization is mainly to balance the amount of power that is consumed by resistance. The active equalization is mainly to transfer the power of batteries with more power to less powerful batteries through capacitance, inductance or transformer. The comparison of passive and active equalization is shown in the table below.

Because the active equilibrium system is relatively complex and the cost is relatively high, the mainstream is still passive equilibrium.

Comparison item Passive equilibrium Active equilibrium
Equilibrium mode Resistance consumption Inductive equivalent transfer
Equilibrium efficiency Low High
Program maturity mature More Mature
System complexity Low High
System cost LOW High
  1. SOC calculation, battery power calculation is a very important part of BMS, many systems need to know the remaining power more accurately. Due to the development of technology, there are many methods for SoC calculation. If the accuracy requirements are not high, the residual power can be judged according to the battery voltage. The main and accurate methods are the current integration method (also called ah method), q = ∫ I DT, internal resistance method, neural network method, Kalman filter method, etc. The current mainstream in the industry is still the current scoring method.
  2. Communication. Different systems have different requirements for communication interfaces. The mainstream communication interfaces are SPI, I2C, can, RS485, etc. The automobile and energy storage systems are mainly can and RS485.

Due to the insufficient competition and the complexity of the BMS system, there are relatively few system manufacturers. The related chip manufacturers are mainly European and American manufacturers, and there are a few large companies in China as well. There are many opportunities in the future.

I hope that I can send an email to communicate with you about the technology, products, and manufacturers in BMS.

(12) Li-ion Battery charging requirements and systems

The mainstream charging method of lithium battery is constant current and constant voltage (CC / CV): constant current – constant voltage. The constant current if charged first and then the constant voltage is charged after reaching a certain potential.. A good charger can also trickle according to the battery voltage state. Some systems also add pulse charging mode in the back and set the end of charging according to the time.

General chargers integrate functions such as current limiting, voltage limiting, overvoltage protection, overcurrent protection, overtemperature protection, and anti-reverse connection. The specific charging system is shown in the figure below.

In addition, the charger charging is usually combined with PCM or BMS to do energy balance in the constant voltage charging stage.

For an ordinary lithium cobalt oxide battery, if the battery voltage is lower than 3.0V, the charger will start trickle charging (about 0.1C) to avoid damage to the battery. When the battery voltage is charged to 3.0V, it is changed to constant current charging (about 1C, the current depends on the system). It is detected that the battery voltage is converted to constant voltage charging when the battery voltage reaches 4.1V. When the battery current drops to about 0.1C, the charging is completed, and the charging system and the charging circuit are closed. The charging curve is shown in the figure below.

According to the different power, the charger adopts different control technology. The linear power supply is the main scheme for low power, and the switching power supply is the main scheme for high power. Charger technology has been quite mature, charger performance and efficiency are basically able to reach a relatively good level. There are many related manufacturers. The main technologies involved in the charger are mainly power supply technology and battery technology. The related manufacturers have also done power supply manufacturing before.

(13) Application fields of lithium batteries

Batteries are mainly used in consumer products, digital products, power products, medical and security.

Motive power Consumer Electronics Digital Health care Security Electrothermal Others
electric automobile Mobile phone Digital camera Palm electrocardiograph  Fire Emergency Light Warm clothing Electronic menu
Electric bicycle Notebook Digital vidicon vital signs monitor Security camera Heating cloths Electric shaver
Electric motorcycle Tablet PC Bluetooth headset A portable ultrasonic diagnostic instrument POS machine Handwarmer Wireless charging
Energy storage system Netbooks Wireless mouse Portable oximeter Wireless call Heated insole Military equipment
Backup power ups MID Bluetooth Keyboard Portable fetal sound monitor Wireless doorbell Warm gloves Well detection
Electric tool GPS Car kit Laser treatment instrument Entrance guard system searchlight
model airplane E-book LED flashlight Wireless electronic medical fingerprint identification LED Screen
Wireless speaker Endoscope RFID monitoring LED Solar Street Light
Eyecare Zig Bee anti-theft
Physiotherapy products
Solar_Energy_Panel_Solar_Panel_Lamps_renewable_Electricity

Top 3 factors to choose outdoor solar lights properly

Users or consumers often find there are lots of key factors in selecting outdoor solar lights,hence, we figure out top 3 factors here.

Top 3 Factors to Choose Outdoor Solar Lights

We all understand that we shall make a good quality product for our users across the world. No matter they are coming from Malaysia, Saudi, UAE, Sweden, Brazil, Australia, South Africa, Namibia, Uganda, or elsewhere, they will all be treated with a high standard quality product. Mostly, the solar-powered street lights are all in one type in the market. All in one is actually three in one type. Three means three major parts for solar street lights, i.e.  solar panel, LED light, and battery. Therefore, I am recommending use to take a look at these top 3 factors before buying solar-powered street lights. Let’s begin.

 

1 – EFFICIENT SOLAR PANEL FOR OUTDOOR SOLAR LIGHTS

copper-mountain-Nevada-Solar_PANEL-field-largest-photovoltaic-plant-top-3-factors-outdoor-solar-lights

Barack Obama in the largest photovoltaic plant in Nevada

 

It took around two decades for photovoltaics (PV) or solar PV to become a mainstream electricity source from small scale applications. Price in the past could only be accepted by users like military and aerospace who don’t really care about the cost too much. Now, the price has dropped to a level that is affordable to civil users.

Solar panel energy has been developed for many years. Technically speaking, the product is mature enough. Usually, the high-efficiency solar cell will come with an MPPT controller for stable performance. The controller also takes care of light absorption in summer and winter.

As regards to the efficiency, monocrystalline solar panels are higher efficiencies and sleeker aesthetics than polycrystalline solar panels. Doubtlessly, polycrystalline panels are sold at a lower price.

Both monocrystalline and polycrystalline solar panels serve the same function in the solar PV system: they capture energy from the sun and turn it into electricity. The technology is so powerful that it can even work and provide lighting under weak light conditions. This is especially helpful in wintertime for high latitude areas like Sweden and Canada. Our customer in Sweden is continuously buying solar-powered street lights from us which is a great honor to us. It is sure that we have installed a special component unit for Sweden market which need complementary power in winter.

As mentioned, the solar panel industry has been developed for so many years. The solar panel itself is guaranteed with at least 20 years lifespan in most cases.

 

2 – OPTIMIZED LED LIGHTING SYSTEM

LED-bulb-colorful-diode-light-technology-electricity
The top 3 factors for outdoor solar lights go number 2. LED chips are various and different chip vendors provide respective lighting solutions. Bridgelux, Cree, Lumileds, Nichia, OSRAM and Philips are common choices of solar lights factories who cherish their product quality and reputation.

For example, when we choose Bridgelux, we will take into consideration of LED power and lumen efficacy into consideration after comparison between brand and brand. Bridgelux has great performance regarding ESD protection. ESD protection devices (anti-static components) protect a circuit from Electrostatic discharge (ESD). The value of ESD for Bridgelux can be as high as 3000V. The product of the brand has high stability because it has a double electric shock structure and has 6 protective films on the surface. The factory is easier to operate in the downstream production process while the product yield is better controlled. At the same time, the light decay is less.

As a whole, other brands are also being picked for use when we produce a specific item since we need to consider the system output performance.

 

3 ENHANCED BATTERY UNIT EMPOWERS SYSTEM PERFORMANCE

Lithium-ion-Battery
The battery unit is outsourced from battery vendor. If an outdoor solar light manufacturer wants to use a low-cost component, then a lead-acid battery is possibly being used. The lead-acid battery has one of the lowest power-to-weight & power-to-volume battery designs in existence, making it big and heavy for the total amount of power it can put out.

In past years, quite many off-grid energy systems are equipped with lead-acid batteries. Now, most of them are defunct or replaced. People are turning to the solution of LiFePO4 lithium-ion battery.

LiFePo4 battery pack with 2000 times long life circles which is 3 times longer than Lead-Acid battery. When you browsing on the internet shopping site for outdoor solar lights, some vendors will indicate the warranty time of the product. Some warranties are so short that you will question yourself for what circumstance a customer will buy and question sellers for what kind of product they are selling at such a low price.

Moreover, please be aware of some suppliers who are using second-hand batteries taking down from electric vehicles.

Above the top 3 key factors are of fundamental importance as they are the main parts of outdoor solar lights.

We are carefully selecting our battery vendor and use the lithium battery product that can support a longer lifespan which is beneficial to both customers and us.

For more details, please check our web site or just send a query to us for a prompt and professional response.

 

Related article:

5 Tips to Make Solar LED Lights Last Longer
https://www.luxmanlight.com/5-tips-to-make-solar-led-lights-last-longer

How to choose batteries for your solar street lamp project?

Outdoor Solar street lamp battery equipment has a built-in type, Pole mount type, and buried type.

solar street light battery

                             Built-in type                            Buried type                           Pole mount type

Built-in is the lithium battery pack integrated together into the lamp body; If an external pole mount type is selected, it is better to install the equipment on the solar street lamp with a height of 6 meters, and there should be no climbing objects beside the solar-powered streetlamp, also pay attention to anti-theft. If to choose the buried type, it is best to pay attention to anti-theft, waterproof, pouring cement ground to density, and replaceability.

The battery is a very key component of the solar-powered street lights system, and also a major component of the solar-powered street lights system cost. At present, solar street lamps mainly use Gel batteries and lithium batteries.

First, explain the concept of both:

Gel batteries belong to a development classification of lead-acid batteries. The method is to add a gelling agent in sulfuric acid to make the electro liquid of sulfuric acid become colloidal. Electrohydraulic colloidal batteries are commonly referred to as colloidal batteries.

 

The lithium battery is a kind of lithium metal or lithium alloy as a negative material, using a non-aqueous electrolyte solution, compared to a commonly used colloidal battery, the lithium battery is more environmentally friendly, lightweight and longer life, of course, the price of lithium battery will be slightly higher

solar street light battery in china

The lithium battery is a kind of lithium metal or lithium alloy as a negative material, using a non-aqueous electrolyte solution, compared to a commonly used colloidal battery, the lithium battery is more environmentally friendly, lightweight and longer life, of course, the price of lithium battery will be slightly higher.

 

Lithium battery

Gel battery, lithium battery have their own characteristics, but in recent years lithium battery solar street lamp systems develop much better, what are their advantages? Let’s briefly compare the differences between the two:

 

  1. Solar-powered street lights  power supply method:

Lithium battery 12V 120AH storage power, higher than the colloidal battery 12V 120AH storage power, lithium battery can be full of release, lithium battery cycle high life is 3~5 times than the colloidal battery.

 

  1. The maintenance cost of solar-powered street lights

Gel battery service life in 2-3 years, lithium battery service life in 5~8 years, to ensure almost no maintenance costs.

 

  1. Are solar-powered street lights environmentally friendly?

Gel battery production pollution is serious, can not be recycled and used, heavy metal pollution is serious, non-environmentally friendly batteries;

The lithium battery is an environmentally friendly battery, lithium belongs to the light element, is harmless to the human body, iron in the soil is ubiquitous.

 

  1. The material cost of solar led street lights:

Gel battery production technology is difficult, high cost; Lithium-ion batteries are environmentally friendly and cost slightly more than colloidal batteries. But overall accounting down, the lithium battery solar street lamp cost is more cost-effective.

  1. The installation cost of solar led street lights:

Gel battery is relatively bulky, generally need to be buried, must do waterproof anti-theft work, installation labor cost is high, late maintenance cost is also very high; Lithium battery is lightweight, high energy density, generally integrated in the inside of the lamp body or under the solar panel, the battery installation does not need labor costs, the maintenance is simple and convenient.

solar street light design

By comparison, we can see why more and more solar street lamps look less bulky than before, due to the use of lithium batteries. The lithium battery is used in solar street lamp systems, and has the advantages that ordinary Gel solar street lamp battery does not have:

I. The charging and discharging system of lithium batteries generally adopts the integrated structure of lithium battery and controller, which is an energy storage battery system with no pollution.

II. According to the user’s demand, the remaining capacity, operation days and nights, weather conditions, and other factors can be intelligently optimized and calculated, and the power level can be reasonably distributed. The functions of light control, time control, and memory storage, to ensure the intelligent setting of the solar street lamp system.

III,  Lithium battery due to dry battery nature, more stable than Gel battery, safer.

IV,  Lithium battery weight is light, the same capacity specification weight is about 1/6-1/5 of the lead-acid Gel battery;

V,  The environmental adaptability of lithium battery is stronger, the use of a wide temperature range can be used in the -20℃- 60℃ environment, after technical treatment, even can be used in the -45℃ environment, which also provides conditions for the promotion of solar street lamps in cold areas.

 

Related article:

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solar battery manufacturer in china

Lithium iron phosphate batteries (LiFePO4 battery) or Ternary lithium battery ?

How to choose a solar street light battery?

As we all know, more and more people are buying integrated solar street lights, and one of the keys points of the Solar Street Light quality is the selection of solar street light batteries. Usually, we use Ternary Lithium batteries or LiFePO4 batteries. Let’s compare the difference between the two.

First of all, why we use lithium batteries?

Lithium batteries (Li-ion, Lithium Battery): Lithium batteries are widely used because of their advantages of a lightweight, large capacity and no memory effect. The energy density of lithium batteries is very high, and their capacity is 1.5-2 times that of Ni-MH batteries of the same weight. (SYLVANIA solar street lamps adopted Ni-MH batteries) Lithium also has a low self-discharge rate. In addition, lithium batteries have few “memory effects” and no toxic substances, which are also important reasons for their wide application.

32700 battery

Ternary Lithium batteries and LiFePO4 batteries are the two main types of Lithium Batteries that are used for Solar lighting products.

Ternary lithium battery Vs lithium iron phosphate battery

I:  The material system of a LiFePO4 battery and a ternary Lithium battery is different.

II:  A LiFePO4 battery is a 3.2V voltage platform, with a cycle life of more than 2000 charges.

III:  The ternary lithium battery is a 3.7V voltage platform, and the cycle life depends on different manufacturers, different models, and processes, and generally, it is 500-800 charge cycles.

IV:  LiFePO4 batteries offer better high-temperature performance, while ternary lithium batteries have better low-temperature performance.

V:  LiFePO4 solar street light batteries are safer.

Further analysis of the two kinds of lithium batteries,

LiFePO4 batteries are characterized by high safety, high rate charge-discharge characteristics and long cycle life. The battery capacity is 80% of the initial capacity after 1600 cycles when the charging condition is 1C multiple charging to 3.65V, then the constant voltage is changed to 0.02C, and then the discharge voltage is 2.0V at 1C multiple charging to 2.0V cut-off voltage. LiFePO4 batteries also have stable charge-discharge characteristics and good fast charge characteristics. In addition to its long life and excellent charge-discharge performance, the greatest advantage of LiFePO4 batteries is their safety. The chemical properties of liFePO4 batteries are stable and the high-temperature stability is good. The LiFePO4 batteries begin to decompose at 700-800 C, and will not release oxygen molecules in the face of impact, needling, short circuit, and so on. It will not produce intense combustion and has high safety performance

32700 battery cell

The disadvantage of a LiFePO4 battery is that its performance is greatly affected by temperature, especially in a low-temperature environment, where the discharge capacity and capacity will be greatly reduced. In addition, there are some performance defects in lithium iron phosphate. The energy density of the battery is low, only the weight energy density of the battery is 120Wh/kg. If the energy density of the whole stack, including the battery management system, heat dissipation, and other components is calculated, it will be lower. The cost of material preparation and the cost of battery manufacturing are higher, the yield of the battery is low and the consistency is poor. The cost per pack is higher than that of ternary lithium batteries

Ternary lithium batteries refer to lithium batteries containing transition metal lithium-intercalated oxides containing nickel, cobalt and manganese, which can be expressed as LiMnxNiyCo1-x-yO2 (0 < x < 0.5, 0 < y < 0.5). This material combines the advantages of lithium cobalt oxide, lithium nickel oxide, and lithium manganate, and forms a ternary synergistic effect of three materials, whose comprehensive properties are superior to any single combination compound. Weight energy density can reach 200Wh/kg

The safety of ternary lithium batteries is poor. The thermal stability of ternary lithium batteries is poor. They will decompose at 250-300C. When it encounters flammable electrolytes and carbon materials, decomposition will start at a point. The heat generated will further intensify the decomposition of the positive pole, and it will deflagrate in a very short time. In a car accident, the impact of external force can damage the battery diaphragm, which will lead to a short circuit, and the heat generated during the short circuit will cause the thermal temperature to rapidly rise to more than 300 C, creating the risk of spontaneous combustion. Therefore, for ternary lithium batteries, the battery management system and heat dissipation system are very important.

From the solar street light battery knowledge above, you can know whether the light purchased is a high or low-quality version.

If you purchase Integrated solar LED street lamps only marked “Lithium battery”, you have to know it uses LiFePO4 batteries or other Lithium batteries. Most of the time it will be ternary Lithium batteries. If it is ternary lithium power, do not expect a five-year service life guarantee.

 

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