solar battery

Types of Battery Used in Solar Lights and Advantage

Solar lights can use different kind of battery types. Below we shall explain you different kinds of rechargeable battery which one can use in solar lights.

 

Lead–acid battery and SMF.

lithium ion battery or Li-ion.

lithium ion battery phosphate or LiFePO4.

LEAD-ACID BATTERY AND SMF:

Because of the price advantage people widely use lead acid batteries. It is inexpensive compared to new technologies batteries. But there are many disadvantages compared to Li-ion an LifePO4. It need regular maintenance, Risk of explosion is more, there are lot of environment concerns as it contains lead and it will be difficult to handle extreme weather conditions. Life of the battery is around 3 – 4 years.

 

Two of the biggest disadvantage of using lead acid battery is it needs a bigger solar panel for charging and size of battery is bigger and will require lot of space. Solar panel will have to generate at least 12 V to charge the battery. That means during cloudy days it will be difficult to generate 12 V.

 

LITHIUM ION BATTERY OR LI-ION:

Li-ion battery is compact and priced higher compared to Lead-acid battery. It requires 3.7 V of power for charging. That means solar panel size will be smaller. During cloudy days’ solar panel can generate 3.7 V and these batteries will easily charge.

 

These batteries require no maintenance and life of battery will be 5 – 6 years. Only disadvantage is there might be chances of explosion in extreme weather. Li-ion batteries efficiency reduces during Very high or very low temperatures.

 

LITHIUM ION PHOSPHATE BATTERY OR LIFEPO4.

LiFePO4 battery is compact and priced higher compared to Li-ion. It is most advanced battery type currently available in market. It requires 3.2 V of power for charging. That means solar panel size can be smaller. During cloudy days’ solar panel can generate 3.2 V and these batteries will easily charge.

 

These batteries require no maintenance and life of battery will be 9 – 12 years. Advantages of using this battery is it can with stand extreme weather conditions. Hence this is most safer battery.

 

Usage of Batteries in Solar Lights.

Lead acid batteries are widely in usage for home lighting system and emergency solar lights. Usage of Li-ion and LiFeP04 batteries are in integrated solar light system. All in One lights like, Solar Garden Lights, Solar Street Light, Solar Flood Lights etc. uses these battery types.

 

Solar Home Lighting System :

Home Lighting system requires bigger battery capacity. Bigger battery means more price.  Hence in India people use LED acid batteries. These batteries are manufactured in India unlike Li-ion and LiFeP04 batteries are imported.  These batteries require regular maintenance the life span in less compared to other batteries types.

 

Solar Street Light and Solar Garden Lights:

All the three batteries are available for solar street lights. People have started switching to Li-ion and LiFeP04 batteries for street lights. Li-ion and LiFeP04 batteries are not manufactured in India, It is imported from China, Japan or Taiwan. India has started research on development of Li-ion cell in 2018. Once they start manufacturing these batteries product cost is go down by 20%.

Lipo Battery

One thing is for sure: lithium battery technology is currently leading the way in the field of mobile power supply. Just look in your pocket: There is no smartphone that is not powered by a lithium polymer battery. Since the Swedish mobile phone provider Ericsson launched the first mobile phone with a lithium polymer battery in 1999, the technology has become an indispensable part of the industry. The reasons are manyfold.

 

Just like lithium ion batteries, lithium polymer batteries have a very high energy density compared to other cell chemistries and are therefore particularly powerful. At the same time, they are extremely durable thanks to the low self-discharge of the battery cells.

 

Same Performance, Higher Flexibility

The flexibility of their design makes lithium polymer batteries particularly attractive. While lithium ion cells always have a sturdy metal housing, lithium polymer cells are only enclosed in a thin layer of plastic-laminated aluminium foil. In addition, the sandwich like structure of the lithium polymer cells enables significantly flatter battery designs than what is possible with lithium-ion batteries. Thanks to these two factors, lithium polymer batteries are available in almost every imaginable size. Even curved designs, for example for fitness bracelets or smartwatches, as well as ultra-thin batteries with a thickness of less than one millimeter are feasible.

 

Due to their flexibility and performance, lithium polymer batteries are in demand not only in mobile communications and consumer applications, but also in other industries such as medical technology. At the same time, however, the high voltage and the absence of a protective metal housing pose new challenges.

 

Safe Handling of Lithium Polymer Batteries

First, it must be considered that the cells of a lithium polymer battery expand while charging. If the battery is discharged, the cell reduces its thickness. This phenomenon, known as “swelling”, can cause lithium polymer cells to expand by up to ten percent of their original thickness over several cycles. Manufacturers of battery powered products should take this into account and calculate the size of the battery compartment accordingly. In addition, no sharp edged components should be placed in the immediate vicinity of the battery compartment, as they could potentially damage the battery.

 

Finally, lithium polymer cells require protective electronics for safe operation. This “Protection Circuit Module” (PCM) interrupts the circuit in critical operating conditions such as overcharging, short circuit or deep discharge.

 

As you can see: lithium polymer batteries are as powerful as they are demanding. For this reason, Jauch supports its customers throughout the entire project phase: from planning to developing the right battery pack and programming the right protective electronics. An overview of the entire Jauch portfolio of lithium polymer batteries can be found here.

PROPERLY MAINTAIN AND EXTEND THE LIFE OF YOUR RV BATTERIES BY UNDERSTANDING THE BASICS OF YOUR RV BATTERIES AND HOW THEY WORK.

To properly maintain and extend the life of your RV batteries you need to have a basic understanding of what a battery is and how it works. Batteries used in RVs are lead acid batteries, which means they have several cells connected in series. Each cell produces approximately 2.1 volts, so a 12-volt battery with six cells in series produces an out put voltage of 12.6 volts. Lead acid batteries are made of plates, lead and lead oxide submersed in electrolyte that is 36 percent sulfuric acid and 64 percent water. Lead acid batteries don’t make electricity they store electricity. The size of the lead plates and the amount of electrolyte determines the amount of charge a battery can store.

Now it’s very important that you use the right battery for the type of application. The battery used to start and run the engine is referred to as a chassis battery or a starting battery. Vehicle starters require large starting currents for short periods. Starting batteries have a large number of thin plates to maximize the plate area exposed to the electrolyte. This is what provides the large amount of current in short bursts. Starting batteries are rated in Cold Cranking Amps (CCA). CCA is the number of amps the battery can deliver at 0 degrees F for 30 seconds and not drop below 7.2 volts. Starting batteries should not be used for deep cycle applications.

The battery or batteries used to supply 12-volts to the RV itself are commonly referred to as house batteries. House batteries need to be deep cycle batteries that are designed to provide a steady amount of current over a long period. Starting batteries and marine batteries should not be used in this application. True deep cycle batteries have much thicker plates and are designed to be deeply discharged and recharged repeatedly. These batteries are rated in Amp Hours (AH) and more recently Reserve Capacity (RC).

The amp hour rating is basically, how many amps the battery can deliver for how many hours before the battery is discharged. Amps times hours. In other words a battery that can deliver 5 amps for 20 hours before it is discharged would have a 100 amp hour rating 5 Amps X 20 Hours = 100Amp Hours. This same battery can deliver 20 amps for 5 hours 20 Amps X 5 Hours = 100 Amp Hours. Reserve Capacity rating (RC) is the number of minutes at 80 degrees F that the battery can deliver 25 amps until it drops below 10.5 volts. To figure the amp hour rating you can multiply the RC rating by 60 percent. RC X 60 percent.

The two major construction types of deep cycle batteries are flooded lead acid and Valve Regulated Lead Acid. Flooded lead acid batteries are the most common type and come in two styles. Serviceable with removable caps so you can inspect and perform maintenance or the maintenance free type. In VRLA batteries, the electrolyte is suspended in either a gel or a fiberglass-mat. Gel cell batteries use battery acid in the form of a gel. They are leak proof and because of this, they work well for marine applications.

There are several disadvantages to gel cell batteries for RV applications. Most importantly, they must be charged at a slower rate and a lower voltage than flooded cell batteries. Any overcharging can cause permanent damage to the cells. Absorbed Glass Mat, or AGM Technology, uses a fibrous mat between the plates, which is 90 percent soaked in electrolyte. They are more expensive than a standard deep cycle battery but they have some advantages. They can be charged the same as a standard lead acid battery, they don’t loose any water, they can’t leak, they are virtually maintenance free and they are almost impossible to freeze.

The life expectancy of your RV batteries depends on you. How they’re used, how well they’re maintained, how they’re discharged, how they’re re-charged, and how they are stored, all contribute to a batteries life span. A battery cycle is one complete discharge from 100 percent down to about 50 percent and then re-charged back to 100 percent. One important factor to battery life is how deep the battery is cycled each time. If the battery is discharged to 50 percent everyday, it will last twice as long as it would if it is cycled to 80 percent. Keep this in mind when you consider a battery’s amp hour rating. The amp hour rating is really cut in half because you don’t want to completely discharge the battery before recharging it. The life expectancy of a battery depends on how soon a discharged battery is recharged. The sooner it is recharged the better.

What does all of this mean to you? That depends on how you use your RV. If most of your camping is done where you are plugged into an electrical source then your main concern is just to properly maintain your deep cycle batteries. But if you really like to get away from it all and you do some serious dry camping you’ll want the highest amp hour capacities you can fit on your RV.

Deep cycle batteries come in all different sizes. Some are designated by Group size, like group 24, 27 and 31. Basically, the larger the battery the more amp hours you get. Depending on your needs and the amount of space you have available, there are several options when it comes to batteries.

You can use one 12-volt 24 group deep cycle battery that provides 70 to 85 AH.

You can use two 12-volt 24 group batteries wired in parallel that provides 140 to 170 AH. Parallel wiring increases amp hours but not voltage.

If you have the room, you can do what a lot of RVers do and switch from the standard 12-volt batteries to two of the larger 6-volt golf cart batteries. These pairs of 6-volt batteries need to be wired in series to produce the required 12-volts and they will provide 180 to 220 AH. Series wiring increases voltage but not amp hours.

If this still doesn’t satisfy your requirements you can build larger battery banks using four 6-volt batteries wired in series / parallel that will give you 12-volts and double your AH capacity.

 

How lipo battery’s performance affected by temperature?

Himax lipo battery

I think everyone here must have the similar experience with me, your smartphone will consume very fast, your phone will dead for only half a day. In fact, the lithium-ion polymer batteries are the vast majority used of smartphones, and a variety of factors will affect the performance of the lipo battery. These factors are similar to RC devices such as our drones and RC car. Especially for temperature factors, so let’s talk about how temperature affects the performance of the battery and why it affects it.

Does temperature affect lipo battery’s performance?

Battery in high temperature or low-temperature environment affect the performance of the battery? Let’s first look at the following chart:

I think everyone here must have the similar experience with me, your smartphone will consume very fast, your phone will dead for only half a day. In fact, the lithium-ion polymer batteries are the vast majority used of smartphones, and a variety of factors will affect the performance of the lipo battery. These factors are similar to RC devices such as our drones and RC car. Especially for temperature factors, so let’s talk about how temperature affects the performance of the battery and why it affects it.

Does temperature affect lipo battery’s performance?

Battery in high temperature or low-temperature environment affect the performance of the battery? Let’s first look at the following chart:

We can see that during the battery used, the higher electric current, faster voltage decay speed, and overload of the high current is more likely causing the battery to be over-discharged and damaged (safety level reduced, life decay is too fast). Therefore, the ambient temperature has a great influence on the performance of the battery, and the lower the temperature, the lower the discharge platform and efficiency.

Low temperature harm battery capacity

The optimal level of operating temperature for lithium batteries is 0 to 35℃. The low-temperature environment will reduce the activity of lithium ions, the lipo battery discharge capacity will be weak, and the use time will be shortened. If the lithium battery using in a low-temperature environment for a short period of time, the damage is only temporary and does not damage the battery capacity. The performance will recover when reinforcing the temperature.

However, if the battery is charged and discharged in a low-temperature environment for a long time, metal lithium will be separated out on the surface of the “battery anode”. This process is irreversible and permanently damage to the battery capacity. Like sometimes, at low temperatures, our smartphone will automatically shut down. It is for the purpose of protecting the battery, on the other side, it is also caused by the unqualified and aging of the self-battery.

So, how to use batteries in an extreme environment?

Recommendations in Summer, or High temperature environment:

– Charging

The charging temperature range from 5 to 45°C;

The upper limit voltage of charging shall not exceed 4.22V. The temperature at the period of charging shall not exceed 45 °C;

Charging needs to be charged at room temperature (≤35 °C), used within 48 hours after charging, if not used, timely discharge to the storage voltage (3.8-3.9V);

The battery cannot be charged immediately after high-temperature discharge or high temperature, and the battery surface temperature can be charged below 40 °C.

Must use the manufacturer’s matching charger for charging, can not illegally use other equipment to carry out large current on the battery (≥1.5C)

The upper limit voltage of charging shall not exceed 4.22V. The temperature during charging shall not exceed 45 °C.

– Discharge

The temperature range during discharge is within 45 ° C;

The discharge current shall not exceed the maximum current identified in the specification;

The lower limit alarm voltage of discharge shall not be lower than 3.6V, the rebound voltage shall not be lower than 3.65V, and the surface temperature of the battery after high current discharge shall not exceed 70°C;

The battery should not be exposed to the sun before and after discharge. The surface temperature of the battery before discharge should not exceed 45 °C.

Recommendations in Winter, or Low temperature environment:

– Charging

Charging should be carried out at room temperature (5 ° C or above, 20 ° C is best), such as indoors, cars, etc., and can not be charged in high ≥ 40 °C environment;

Retrieving the battery from the outside cannot be charged immediately, and then charging the battery after the surface temperature of the battery reaches the room temperature environment;

must use the manufacturer’s matching charger for charging, can not illegally use other equipment to carry out large current on the battery (≥1.5C)

– Discharge

After discharge, the battery should be effectively insulated (such as using a thermos cup, incubator, etc.) to ensure that the temperature of the battery body is kept above 10 °C, 20 °C is best.

After the battery is loaded into the aircraft, it is necessary to check the remaining battery power from the APP, and whether the voltage information is abnormal;

When the battery temperature does not reach 20 °C or above, it is not suitable for large maneuvering.

Compared with the room temperature (about 20 °C), the battery life of the battery will be significantly shortened in the low-temperature environment. After the low battery alarm, the drone should be returned immediately for charging.

Use high temperature, Low-temperature resistant lithium batteries

In order to ensure the life and safety of the lithium battery, the protection management system (BMS system) is adopted in the battery pack of the high-temperature lithium battery to prevent overcharging, over-discharging, high-temperature operation, low-temperature charging, or short circuit, and even safety problem. Such as Himax fast-charge battery, the temperature will rise steadily during the fast charging process. The surface temperature of the fast charge battery must not exceed 65 degrees Celsius. During the fast charging process, the temperature will rise stably. The surface temperature of the battery will not exceed 65 degrees Celsius.

Other battery option: LiFePO4 Battery

In other application areas, like e-bike, camping portable power station, usually choose Lithium Iron Phosphate Battery (LiFePO4 Battery), also called LFP battery. It is a type of rechargeable battery. LiFePO4 technologies offer high-powered cell performance compatible with lots of lithium-ion application to deliver more power and extend life, also has these six advantages:

Good high-temperature resistance.

No memory effect

Higher-capacity compare with same size lead acid battery

Longer cycle life than other lithium-ion batteries

Good safety characteristics and Eco-friendly

Ideal drop-in replacement for lead-acid batteries

If you have more opinions and ideas, please feel free to comment below. If you want to know more, you can keep following our website.

 

 

Solar Battery

Top Benefits of Solar Battery Storage for Your Home

If you have solar panels or are looking to install solar panels, you want to get the most out of your energy system. Installing solar battery storage for excess electricity generated by your panels is one great way to improve your electricity generation system’s performance throughout the day. Here are the top benefits of solar battery storage.

Power When You Need It
One of the biggest problems with solar panels is that they only produce electricity when there’s light outside. Usually, this is when you’re not at home because of daytime activities like work and kid’s sports. Clouds and shade can also reduce the output of solar panels, causing your home to have to draw off the grid if it’s using too much electricity. With a battery, the energy that your solar panels create that isn’t used at the time of its generation gets stored. You can use the stored energy at night or doing those cloudy times when you’re at home without having to draw off the grid.
Solar Battery

Energy Security

The ability to store energy allows you to be less dependent on the grid for additional power. If you live in a place that experiences frequent brownouts or has a decaying energy infrastructure, solar batteries can help insulate you from the consequences of poor grid management. You move to greater self-sufficiency and are more in control of your energy destiny. This is great for people who are looking to get off the grid.

Better for the Environment

Most electricity on the grid is generated through coal plants and other fossil fuels. Storing your energy allows you to use the most environmentally friendly energy available. Your solar power system will continue to use fewer resources throughout the year while producing little to no waste and pollution. Because of advances in photovoltaic technology, panels create less pollution than fossil fuels during their comparative lifetime uses.

A Quiet Solution

No one wants to have to deal with the roar of a generator as it coughs to life. Even a gentle hum can be disturbing for those who are noise sensitive. Unlike noisy generators run by fossil fuels, solar batteries are silent. You don’t have to worry about trying to sleep at night or annoying the neighbors. You get all the benefits of instant electricity with none of the local pollution—both noise and air—produced by a generator. You also don’t have to store flammable or explosive fuel at your home, so you can enjoy your home and breathe easier—literally and figuratively.

 

Lower Electrical Bills

In some places, the electric utility is required to buy back any energy that you create in excess of what you use. While this results in a lower electric bill for you, using solar storage systems also results in a reduction of your energy bill because you consume less energy from the grid. Generally, the buyback is less than what the energy is sold for, so you get more for your money when you can store and use your own energy. Contact the experts at The Himax battery by visiting https://himax.en.alibaba.com/ and learn more about the solar battery.

 

There’s lots of press about how to conserve battery power, but not much about how to take care of your batteries. Here are a few things you can do to increase battery longevity.

In today’s mobile world, battery life is precious. If you don’t believe me, go to an airport and watch the road warriors. It can get downright nasty when two spot the only available outlet at the same time.

It doesn’t take long to learn what helps preserve the current charge on the battery. What’s not well known is how to care for the battery itself. That’s just as important. Doing so allows the battery to operate efficiently. Here are a few ways to keep your lithium-ion batteries healthy.

1: Keep your batteries at room temperature
That means between 20 and 25 degrees C. The worst thing that can happen to a lithium-ion battery is to have a full charge and be subjected to elevated temperatures. So don’t leave or charge your mobile device’s battery in your car if it’s hot out. Heat is by far the largest factor when it comes to reducing lithium-ion battery life.

2: Think about getting a high-capacity lithium-ion battery, rather than carrying a spare
Batteries deteriorate over time, whether they’re being used or not. So a spare battery won’t last much longer than the one in use. It’s important to remember the aging characteristic when purchasing batteries. Make sure to ask for ones with the most recent manufacturing date.

3: Allow partial discharges and avoid full ones (usually).
Unlike NiCad batteries, lithium-ion batteries do not have a charge memory. That means deep-discharge cycles are not required. In fact, it’s better for the battery to use partial-discharge cycles.

There is one exception. Battery experts suggest that after 30 charges, you should allow lithium-ion batteries to almost completely discharge. Continuous partial discharges create a condition called digital memory, decreasing the accuracy of the device’s power gauge. So let the battery discharge to the cut-off point and then recharge. The power gauge will be recalibrated.

4: Avoid completely discharging lithium-ion batteries
If a lithium-ion battery is discharged below 2.5 volts per cell, a safety circuit built into the battery opens and the battery appears to be dead. The original charger will be of no use. Only battery analyzers with the boost function have a chance of recharging the battery.

Also, for safety reasons, do not recharge deeply discharged lithium-ion batteries if they have been stored in that condition for several months.

5: For extended storage, discharge a lithium-ion battery to about 40 percent and store it in a cool place
I’ve always had an extra battery for my notebook, but it would never last as long as the original battery. I know now that it’s because I was storing the battery fully charged. That means oxidation of lithium-ion is at its highest rate. Storing lithium-ion batteries at 40 percent discharge and in the refrigerator (not freezer) is recommended

Final thoughts
Lithium-ion batteries are a huge improvement over previous types of batteries. Getting 500 charge/discharge cycles from a lithium-ion battery is not unheard of. Just follow the above guidelines.

Solar Battery


Solar batteries are an offshoot of the solar panel industry. With the increase in demand for solar panels for a solar energy system, new technology was born…

solar batteries. These batteries are used to store excess power generated by solar panels. But, how do solar batteries work?

Before going into the workings of a solar battery, it is best to learn first about the solar energy system.

The Solar Energy System

A common solar energy system is made up of solar panels, inverter, power or utility meter to determine the amount of electricity produced and tools for mounting the panels. Solar batteries are an adjunct of the system.

Many of the residential solar energy users are connected to a power or utility grid. When their solar panels are producing more than enough electricity, the surplus is fed into the utility grid. When the solar panels are not producing enough electricity that the home needs, they also can draw from the grid.

A power meter is used to measure what has been fed back and how much has been drawn from the grid. A net metering system is used to keep track of this transactions.

How does the solar energy system work

Solar panels are installed on top of roofs, on a pole or even on the ground. These panels are made of cells that harvest the sun’s’ energy which is called photons. When photons hit the cells in a solar panel, they are converted into electrons or what we call direct current (DC) electricity.

The direct current (DC) then flows from the solar panels to the inverter, and the inverter converts them into alternating current (AC). Households need AC to light up the home and to run home appliances.

Ways to Work Solar Batteries is…

Solar batteries make sure that when you need power, there will be power even when the sun is not shining. It is actually referred to as solar-plus storage.

What solar batteries do is to store surplus energy generated from the solar panels. Homes with solar batteries can accumulate excess solar power that can be used later when there is no more sun, such as at night, when the light is most needed.

Solar batteries have their own inverter that converts DC to AC. As they draw DC power from the solar panels, this is converted into AC. The electricity in excess of what the home needs charge the batteries. Homes connected to the grid only send excess electricity to the grid once the batteries are fully charged.

Solar batteries also double as a backup power source when there is power interruption in the community, although for short periods of time only.

So, how do solar batteries works? Easy! It converts DC electricity to AC for home use to operate household appliances. And whatever excess electricity is generated from the solar panels are stored in these batteries to be used or drawn out when needed, such as at nighttime when there is no more sun.

What’s the Best Battery?

We often get puzzled by announcements of new batteries that are said to offer very high energy densities, deliver 1000 charge/discharge cycle and are paper-thin. Are they real?  Perhaps — but not in one and the same battery. While one battery type may be designed for small size and long runtime, this pack will not last and wear out prematurely. Another battery may be built for long life, but the size is big and bulky. A third battery may provide all the desirable attributes, but the price would be too high for commercial use.

 

Battery manufacturers are well aware of customer needs and have responded by offering packs that best suit the specific applications. The mobile phone industry is an example of clever adaptation. Emphasis is placed on small size, high energy density and low price. Longevity comes in second.

The inscription of NiMH on a battery pack does not automatically guarantee high energy density. A prismatic Nickel-Metal Hydride battery for a mobile phone, for example, is made for slim geometry. Such a pack provides an energy density of about 60Wh/kg and the cycle count is around 300. In comparison, a cylindrical NiMH offers energy densities of 80Wh/kg and higher. Still, the cycle count of this battery is moderate to low. High durability NiMH batteries, which endure 1000 discharges, are commonly packaged in bulky cylindrical cells. The energy density of these cells is a modest 70Wh/kg.

Compromises also exist on lithium-based batteries. Li-ion packs are being produced for defense applications that far exceed the energy density of the commercial equivalent. Unfortunately, these super-high capacity Li-ion batteries are deemed unsafe in the hands of the public and the high price puts them out of reach of the commercial market.

 

In this article we look at the advantages and limitations of the commercial battery. The so-called miracle battery that merely live in controlled environments is excluded. We scrutinize the batteries not only in terms of energy density but also longevity, load characteristics, maintenance requirements, self-discharge and operational costs. Since NiCd remains a standard against which other batteries are compared, we evaluate alternative chemistries against this classic battery type.

Nickel Cadmium (NiCd) — mature and well understood but relatively low in energy density. The NiCd is used where long life, high discharge rate and economical price are important. Main applications are two-way radios, biomedical equipment, professional video cameras and power tools. The NiCd contains toxic metals and is environmentally unfriendly.

Nickel-Metal Hydride (NiMH) — has a higher energy density compared to the NiCd at the expense of reduced cycle life. NiMH contains no toxic metals. Applications include mobile phones and laptop computers.

 

Lead Acid — most economical for larger power applications where weight is of little concern. The lead acid battery is the preferred choice for hospital equipment, wheelchairs, emergency lighting and UPS systems.

Lithium Ion (Li-ion) — fastest growing battery system. Li-ion is used where high-energy density and lightweight is of prime importance. The technology is fragile and a protection circuit is required to assure safety. Applications include notebook computers and cellular phones.

Lithium Ion Polymer (Li-ion polymer) — offers the attributes of the Li-ion in ultra-slim geometry and simplified packaging. Main applications are mobile phones.

 

Figure 1 compares the characteristics of the six most commonly used rechargeable battery systems in terms of energy density, cycle life, exercise requirements and cost. The figures are based on average ratings of commercially available batteries at the time of publication.

Figure 1: Characteristics of commonly used rechargeable batteries

  1. Internal resistance of a battery pack varies with cell rating, type of protection circuit and number of cells. Protection circuit of Li-ion and Li-polymer adds about 100mΩ.
  2. Cycle life is based on battery receiving regular maintenance. Failing to apply periodic full discharge cycles may reduce the cycle life by a factor of three.
  3. Cycle life is based on the depth of discharge. Shallow discharges provide more cycles than deep discharges.
  4. The discharge is highest immediately after charge, then tapers off. The NiCd capacity decreases 10% in the first 24h, then declines to about 10% every 30 days thereafter. Self-discharge increases with higher temperature.
  5. Internal protection circuits typically consume 3% of the stored energy per month.
  6. 25V is the open cell voltage. 1.2V is the commonly used value. There is no difference between the cells; it is simply a method of rating.
  7. Capable of high current pulses.
  8. Applies to discharge only; charge temperature range is more confined.
  9. Maintenance may be in the form of ‘equalizing’ or ‘topping’ charge.
  10. Cost of battery for commercially available portable devices.
  11. Derived from the battery price divided by cycle life. Does not include the cost of electricity and chargers.

Observation: It is interesting to note that NiCd has the shortest charge time, delivers the highest load current and offers the lowest overall cost-per-cycle, but has the most demanding maintenance requirements.

 

The Nickel Cadmium (NiCd) battery

The NiCd prefers fast charge to slow charge and pulse charge to DC charge. All other chemistries prefer a shallow discharge and moderate load currents. The NiCd is a strong and silent worker; hard labor poses no problem. In fact, the NiCd is the only battery type that performs well under rigorous working conditions. It does not like to be pampered by sitting in chargers for days and being used only occasionally for brief periods. A periodic full discharge is so important that, if omitted, large crystals will form on the cell plates (also referred to as memory) and the NiCd will gradually lose its performance.

Among rechargeable batteries, NiCd remains a popular choice for applications such as two-way radios, emergency medical equipment and power tools. Batteries with higher energy densities and less toxic metals are causing a diversion from NiCd to newer technologies.

Figure 2: Advantages and limitations of NiCd batteries.

The Nickel-Metal Hydride (NiMH) battery

Research of the NiMH system started in the 1970s as a means of discovering how to store hydrogen for the nickel hydrogen battery. Today, nickel hydrogen batteries are mainly used for satellite applications. They are bulky, contain high-pressure steel canisters and cost thousands of dollars per cell.

In the early experimental days of the NiMH battery, the metal hydride alloys were unstable in the cell environment and the desired performance characteristics could not be achieved. As a result, the development of the NiMH slowed down. New hydride alloys were developed in the 1980s that were stable enough for use in a cell. Since the late 1980s, NiMH has steadily improved.

The success of the NiMH has been driven by its high energy density and the use of environmentally friendly metals. The modern NiMH offers up to 40 percent higher energy density compared to NiCd. There is potential for yet higher capacities, but not without some negative side effects.

 

The NiMH is less durable than the NiCd. Cycling under heavy load and storage at high temperature reduces the service life. The NiMH suffers from high self-discharge, which is considerably greater than that of the NiCd.

The NiMH has been replacing the NiCd in markets such as wireless communications and mobile computing. In many parts of the world, the buyer is encouraged to use NiMH rather than NiCd batteries. This is due to environmental concerns about careless disposal of the spent battery.

Experts agree that the NiMH has greatly improved over the years, but limitations remain. Most of the shortcomings are native to the nickel-based technology and are shared with the NiCd battery. It is widely accepted that NiMH is an interim step to lithium battery technology.

Figure 3: Advantages and limitations of NiMH batteries

The Lead Acid battery

Invented by the French physician Gaston Planté in 1859, lead acid was the first rechargeable battery for commercial use. Today, the flooded lead acid battery is used in automobiles, forklifts and large uninterruptible power supply (UPS) systems.

During the mid 1970s, researchers developed a maintenance-free lead acid battery that could operate in any position. The liquid electrolyte was transformed into moistened separators and the enclosure was sealed. Safety valves were added to allow venting of gas during charge and discharge.

 

Driven by different applications, two battery designations emerged. They are the small sealed lead acid (SLA), also known under the brand name of Gelcell, and the large valve regulated lead acid (VRLA). Technically, both batteries are the same. (Engineers may argue that the word ‘sealed lead acid’ is a misnomer because no lead acid battery can be totally sealed.) Because of our emphasis on portable batteries, we focus on the SLA.

Unlike the flooded lead acid battery, both the SLA and VRLA are designed with a low over-voltage potential to prohibit the battery from reaching its gas-generating potential during charge. Excess charging would cause gassing and water depletion. Consequently, these batteries can never be charged to their full potential.

The lead acid is not subject to memory. Leaving the battery on float charge for a prolonged time does not cause damage. The battery’s charge retention is best among rechargeable batteries. Whereas the NiCd self-discharges approximately 40 percent of its stored energy in three months, the SLA self-discharges the same amount in one year. The SLA is relatively inexpensive to purchase but the operational costs can be more expensive than the NiCd if full cycles are required on a repetitive basis.

 

The SLA does not lend itself to fast charging — typical charge times are 8 to 16 hours. The SLA must always be stored in a charged state. Leaving the battery in a discharged condition causes sulfation, a condition that makes the battery difficult, if not impossible, to recharge.

Unlike the NiCd, the SLA does not like deep cycling. A full discharge causes extra strain and each cycle robs the battery of a small amount of capacity. This wear-down characteristic also applies to other battery chemistries in varying degrees. To prevent the battery from being stressed through repetitive deep discharge, a larger SLA battery is recommended.

Depending on the depth of discharge and operating temperature, the SLA provides 200 to 300 discharge/ charge cycles. The primary reason for its relatively short cycle life is grid corrosion of the positive electrode, depletion of the active material and expansion of the positive plates. These changes are most prevalent at higher operating temperatures. Cycling does not prevent or reverse the trend.

 

The optimum operating temperature for the SLA and VRLA battery is 25°C (77°F). As a rule of thumb, every 8°C (15°F) rise in temperature will cut the battery life in half. VRLA that would last for 10 years at 25°C will only be good for 5 years if operated at 33°C (95°F). The same battery would endure a little more than one year at a temperature of 42°C (107°F).

Among modern rechargeable batteries, the lead acid battery family has the lowest energy density, making it unsuitable for handheld devices that demand compact size. In addition, performance at low temperatures is poor.

The SLA is rated at a 5-hour discharge or 0.2C. Some batteries are even rated at a slow 20-hour discharge. Longer discharge times produce higher capacity readings. The SLA performs well on high pulse currents. During these pulses, discharge rates well in excess of 1C can be drawn.

 

In terms of disposal, the SLA is less harmful than the NiCd battery but the high lead content makes the SLA environmentally unfriendly.

Figure 4: Advantages and limitations of lead acid batteries.

The Lithium Ion battery

Pioneer work with the lithium battery began in 1912 under G.N. Lewis but it was not until the early 1970s that the first non-rechargeable lithium batteries became commercially available. Lithium is the lightest of all metals, has the greatest electrochemical potential and provides the largest energy density per weight.

Attempts to develop rechargeable lithium batteries followed in the 1980s, but failed due to safety problems. Because of the inherent instability of lithium metal, especially during charging, research shifted to a non-metallic lithium battery using lithium ions. Although slightly lower in energy density than lithium metal, the Li-ion is safe, provided certain precautions are met when charging and discharging. In 1991, the Sony Corporation commercialized the first Li-ion battery. Other manufacturers followed suit. Today, the Li-ion is the fastest growing and most promising battery chemistry.

The energy density of the Li-ion is typically twice that of the standard NiCd. Improvements in electrode active materials have the potential of increasing the energy density close to three times that of the NiCd. In addition to high capacity, the load characteristics are reasonably good and behave similarly to the NiCd in terms of discharge characteristics (similar shape of discharge profile, but different voltage). The flat discharge curve offers effective utilization of the stored power in a desirable voltage spectrum.

The high cell voltage allows battery packs with only one cell. Most of today’s mobile phones run on a single cell, an advantage that simplifies battery design. To maintain the same power, higher currents are drawn. Low cell resistance is important to allow unrestricted current flow during load pulses.

The Li-ion is a low maintenance battery, an advantage that most other chemistries cannot claim. There is no memory and no scheduled cycling is required to prolong the battery’s life. In addition, the self-discharge is less than half compared to NiCd, making the Li-ion well suited for modern fuel gauge applications. Li-ion cells cause little harm when disposed.

Despite its overall advantages, Li-ion also has its drawbacks. It is fragile and requires a protection circuit to maintain safe operation. Built into each pack, the protection circuit limits the peak voltage of each cell during charge and prevents the cell voltage from dropping too low on discharge. In addition, the cell temperature is monitored to prevent temperature extremes. The maximum charge and discharge current is limited to between 1C and 2C. With these precautions in place, the possibility of metallic lithium plating occurring due to overcharge is virtually eliminated.

Aging is a concern with most Li-ion batteries and many manufacturers remain silent about this issue. Some capacity deterioration is noticeable after one year, whether the battery is in use or not. Over two or perhaps three years, the battery frequently fails. It should be noted that other chemistries also have age-related degenerative effects. This is especially true for the NiMH if exposed to high ambient temperatures.

Storing the battery in a cool place slows down the aging process of the Li-ion (and other chemistries). Manufacturers recommend storage temperatures of 15°C (59°F). In addition, the battery should be partially charged during storage.

Manufacturers are constantly improving the chemistry of the Li-ion battery. New and enhanced chemical combinations are introduced every six months or so. With such rapid progress, it is difficult to assess how well the revised battery will age.

The most economical Li-ion battery in terms of cost-to-energy ratio is the cylindrical 18650 cell. This cell is used for mobile computing and other applications that do not demand ultra-thin geometry. If a slimmer pack is required (thinner than 18 mm), the prismatic Li-ion cell is the best choice. There are no gains in energy density over the 18650, however, the cost of obtaining the same energy may double.

For ultra-slim geometry (less than 4 mm), the only choice is Li-ion polymer. This is the most expensive system in terms of cost-to-energy ratio. There are no gains in energy density and the durability is inferior to the rugged 18560 cell.

Figure 5: Advantages and limitations of Li-ion batteries

The Lithium Polymer battery

The Li-polymer differentiates itself from other battery systems in the type of electrolyte used. The original design, dating back to the 1970s, uses a dry solid polymer electrolyte. This electrolyte resembles a plastic-like film that does not conduct electricity but allows an exchange of ions (electrically charged atoms or groups of atoms). The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte.

The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry. There is no danger of flammability because no liquid or gelled electrolyte is used. With a cell thickness measuring as little as one millimeter (0.039 inches), equipment designers are left to their own imagination in terms of form, shape and size.

Unfortunately, the dry Li-polymer suffers from poor conductivity. Internal resistance is too high and cannot deliver the current bursts needed for modern communication devices and spinning up the hard drives of mobile computing equipment. Heating the cell to 60°C (140°F) and higher increases the conductivity but this requirement is unsuitable for portable applications.

To make a small Li-polymer battery conductive, some gelled electrolyte has been added. Most of the commercial Li-polymer batteries used today for mobile phones are a hybrid and contain gelled electrolyte. The correct term for this system is Lithium Ion Polymer. For promotional reasons, most battery manufacturers mark the battery simply as Li-polymer. Since the hybrid lithium polymer is the only functioning polymer battery for portable use today, we will focus on this chemistry.

With gelled electrolyte added, what then is the difference between classic Li-ion and Li-ion polymer? Although the characteristics and performance of the two systems are very similar, the Li-ion polymer is unique in that solid electrolyte replaces the porous separator. The gelled electrolyte is simply added to enhance ion conductivity.

Technical difficulties and delays in volume manufacturing have deferred the introduction of the Li-ion polymer battery. In addition, the promised superiority of the Li-ion polymer has not yet been realized. No improvements in capacity gains are achieved — in fact, the capacity is slightly less than that of the standard Li-ion battery. For the present, there is no cost advantage. The major reason for switching to the Li-ion polymer is form factor. It allows wafer-thin geometries, a style that is demanded by the highly competitive mobile phone industry.

 

 

 

 

 

 

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Lithium Ion vs. Lithium Polymer Batteries – Which Is Better?

Lithium-ion or lithium-polymer? The (what seems like) endless debate on batteries in modern consumer electronics. Today, we’re going to talk about the differences between these battery types. While we may not be able to settle the score once and for all on which is better. we hope to give you the information you need to make the best possible choice!

What’s the Difference?
A lithium-ion battery is a rechargeable battery format that first grew in popularity thanks to their adoption by major electronics companies in the early 1990s. They are essentially a group of very rigid electricity generating compartments, which consists of three pieces: a positive electrode; a negative electrode; and an electrolyte, or liquid chemical compound between them. Most lithium-ion batteries, unlike more traditional ones, also include an electronic controller, which regulates power and discharge flows so your battery doesn’t overheat or explode.

The most significant difference between lithium-ion and lithium-polymer batteries is the chemical electrolyte between their positive and negative electrodes. In Li-Po batteries it isn’t a liquid. Instead, Li-Po technology uses one of three forms: a dry solid, which was largely phased out during the prototype years of lithium polymer batteries; a porous chemical compound; or, a gel-like electrolyte. The most popular among these is the last one, which is the type of battery you’ll find in newer laptop computers and electric cars. The catch is that plenty of companies are not actually selling you a true Li-Po battery, instead it’s a lithium-ion polymer battery, or a Li-ion in a more flexible casing.

Is One Better than the Other?
Both lithium-ion and lithium-polymer batteries have their pros and cons. Typically, the advantages of a lithium-ion is their high power density, lack of what’s called the memory effect (when batteries become harder to charge over time), and their significantly lower cost than lithium-polymer. In the words of Wired, “Lithium-ion batteries are incredibly efficient. They stuff freakish amounts of energy in a tiny package.” But, as anyone might have seen with the recent saga of a certain cellphone brand being banned from flights, lithium-ion batteries are inherently unstable, suffer from aging, and are potentially dangerous. If the barrier that separates the positive and negative electrode is ever breached, the chemical reaction can cause combustion (fire). As Li-ion batteries have become more popular in consumer electronics, businesses have tried to lower costs by cutting corners. While quality batteries are perfectly safe, you should always be careful when buying no-name brands.

Lithium-polymer batteries, on the other hand, are generally robust and flexible, especially when it comes to the size and shape of their build. They are also lightweight, have an extremely low profile, and have a lower chance of suffering from leaking electrolyte. But lithium-polymer batteries aren’t perfect either: they are significantly more costly to manufacture, and they do not they have the same energy density (amount of power that can be stored) nor lifespan as a lithium-ion.

 

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Overview

Lithium iron phosphate batteries pack a lot of power and value into a small package. The chemistry of these batteries is a big part of their superior performance. But all reputable commercial lithium-ion batteries also include another important element along with the battery cells themselves: a carefully designed electronic battery management system (BMS). A well-designed battery management system protects, and monitors a lithium-ion battery to optimize performance, maximize lifetime, and ensure safe operation over a wide range of conditions.

At RELiON, all our lithium iron phosphate batteries include an internal or external BMS. Let’s have a look at how a RELiON BMS protects and optimizes the operation of a lithium iron phosphate battery.

1. Over and Under Voltage

Lithium iron phosphate cells operate safely over a range of voltages, typically from 2.0V to 4.2V. Some lithium chemistries result in cells that are highly sensitive to overvoltage, but LiFePO4 cells are more tolerant. Still, significant overvoltage for a prolonged period during charging can cause plating of metallic lithium on the battery’s anode which permanently degrades performance. Also, the cathode material may oxidize, become less stable, and produce carbon dioxide which may lead to a buildup of pressure in the cell. All RELiON battery management systems limit each cell and the battery itself to a maximum voltage. The BMS in the LiFePO4 battery, for example, protects each cell in the battery and limits the voltage in the battery to 15.6V.

Undervoltage during battery discharge is also a concern since discharging a LiFePO4 cell below approximately 2.0V may result in a breakdown of the electrode materials. Lithium batteries have a recommended minimum operational voltage. In the Himax 12.8V 100Ah, for example, the minimum recommended voltage is 11V. The BMS acts as a failsafe to disconnect the battery from the circuit if any cell drops below 2.0V.

2. Overcurrent and Short Circuit Protection

Every battery has a maximum specified current for safe operation. If a load is applied to the battery which draws a higher current, it can result in overheating the battery. While it’s important to use the battery in a way to keep the current draw below the maximum specification, the BMS again acts as a backstop against overcurrent conditions and disconnects the battery from operation.

Again, using the RB100 as an example, the maximum continuous discharge current is specified at 100A, the peak discharge current is 200A, and the BMS disconnects the battery from the circuit if the load draws about 280A.

A short circuit of the battery is the most serious form of overcurrent condition. It most commonly happens when the electrodes are accidentally connected with a piece of metal. The BMS must quickly detect a short circuit condition before the sudden and massive current draw overheats the battery and causes catastrophic damage. In the RB100, the battery shuts down within 200-600 microseconds of an external short circuit, then resumes normal operation if the short circuit condition is removed.

3. Over Temperature

Unlike lead-acid or lithium cobalt oxide batteries, lithium iron phosphate batteries operate efficiently and safely at temperatures up to 60oC or more. But at higher operating and storage temperatures, as with all batteries, the electrode materials will begin to degrade. The BMS of a lithium battery uses embedded thermistors to actively monitor the temperature during operation, and it will disconnect the battery from the circuit at a specified temperature. In the example of the RELiON RB100, the BMS disconnects the battery at 80oC (176oF) and reconnects the battery at 50oC (122oF).

4. Cell Imbalance

Lithium-ion batteries have a major difference from lead-acid batteries when it comes to balancing the voltage in each individual cell during charging. Because of small differences in manufacturing or operating conditions, each cell in a battery charges at a slightly different rate. In a lead-acid battery, if one cell charges faster and reaches its full voltage, the typical low end of charge current, along with the excess charge-return, will ensure the other cells get fully charged. In a sense, the cells in a lead-acid battery are self-equalizing during charge.

This is not the case with lithium-ion batteries. When a lithium-ion cell is fully charged, its voltage begins to rise further which may lead to electrode damage. If the charge of the entire battery is stopped when only one cell is fully charged, the remaining cells do not reach full charge and the battery will operate below peak capacity. A well-designed BMS will ensure each cell safely and fully charges before the entire charging process is complete.