Browse technical resources about solar storage, BESS, microgrids, telecom power, off-grid systems, data centre UPS, and zero-carbon solutions.
Invented in 1859 by French physicist Gaston Planté, the lead-acid battery is the earliest type of rechargeable battery. In the charged state, the chemical energy of the lead-acid battery is stored in the potential difference between the pure lead on the negative side and the PbO2 on the positive side, plus the aqueous. Lead-acid batteries have their own share of advantages. The following are only some of the advantages that this kind of battery boasts: 1. It is not as expensive as the other kinds of batteries. 2. It has over 140 years of development,. The primary reason why lead-acid batteries are widely used in the solar industry is their cost per kWh. The cost per kWh for lead-acid. Our website lists lead-acid batteries from established brands and manufacturers all over the world. As a result, you can expect that the lead-acid batteries that we offer are of the best variety. They are characterized by higher.
[PDF Version]
The most notable difference between lithium iron phosphate and lead acid is the fact that the lithium battery capacity is independent of the discharge rate. The figure below compares the actual capacity as a percentage of the rated capacity of the battery versus the discharge rate as expressed by C (C equals the. Lithium delivers the same amount of power throughout the entire discharge cycle, whereas an SLA's power delivery starts out strong, but. Charging SLA batteries is notoriously slow. In most cyclic applications, you need to have extra SLA batteries available so you can still use your application while the other battery is charging. In standby applications, an SLA. Cold temperatures can cause significant capacity reduction for all battery chemistries. Knowing this, there are two things to consider when evaluating a battery for cold temperature use: charging and discharging. A lithium. Lithium's performance is far superior than SLA in high temperature applications. In fact, lithium at 55°C still has twice the cycle life as SLA does at.
[PDF Version]
Invented in 1859 by French physicist Gaston Planté, the lead-acid battery is the earliest type of rechargeable battery. In the charged state, the chemical energy of the lead-acid battery is stored in the potential difference between the pure lead on the negative side and the PbO2 on the positive side, plus the aqueous. Lead-acid batteries have their own share of advantages. The following are only some of the advantages that this kind of battery boasts: 1. It is not as expensive as the other kinds of. Our website lists lead-acid batteries from established brands and manufacturers all over the world. As a result, you can expect that the lead-acid batteries that we offer are of the best variety. They are characterized by higher. The primary reason why lead-acid batteries are widely used in the solar industry is their cost per kWh. The cost per kWh for lead-acid batteries remains the most economical for.
[PDF Version][...] Buy Lead Acid Batteries at Screwfix.com. High powered battery for larger electronic products. A rechargeable, cost effective option. Free next day delivery available.
BatteryClerk offers a selection of replacement batteries for Sealed Lead Acid (SLA). Browse our current selection from leading brands like AJC. Info AJC® 12 Volt 7Ah Sealed Leaded Acid Battery Exact OEM replacement guaranteed to fit easily and precisely Maintenance free AGM technology, no n...
Abler Electronics Lanka (pvt)ltd #435/12 Regent Plaza,Colombo 10, Maradana, Sri Lanka Phone : 94112693040 Web : Console Electronics (Pvt) Ltd 171/29, Koswatte Road, Nawala,Sri Lanka Phone : 94 11 2871000 Manufacturers of lead acid batteries. Email : [email protected]
In addition, older Lead-acid batteries may be vulnerable to “sudden death syndrome,” unlike lithium batteries, in which a battery works fine one day but fails to provide sufficient power the next day, resulting in a UPS failure and data center downtime.
It's essential to remember that with lead acid batteries, a controlled room temperature of 77 ̊F (25 ̊C) is necessary to ensure a three-to-five-year lifespan. With every 15 ̊C increase in room temperature, the useful life of a typical VRLA battery is cut in half.
Life span of a VRLA battery When a Lead-acid battery reaches 80% capacity, it is considered at the end of life (EOL). Institute of Electrical and Electronics Engineers (IEEE) standards recommend replacing a battery when its capacity is below 80%.
Batteries have a shelf life and will eventually die even if they're not used. To check the date on a battery, you need to know what the characters on the battery mean. The first character will be a number from zero through nine. The date on top of a battery corresponds to the year and month of manufacture. The number corresponds to the year and the letter corresponds to the month. So, if you see an 8D on your battery, it means that it was manufactured in April. “””The first number is the month and the letter is the year. For example, if the code is 3L, the battery was made in March of 2013. If the code is 11J, the battery was made in November of. This is a question that we get a lot, so we figured we'd answer it here in our blog. To check the date on your Exide battery, all you need to do is find the small white sticker on the top of the battery. This sticker will have a bunch. The battery date code chart is a tool that allows you to determine the date of manufacture for a given battery. The date code is typically stamped on the battery itself, and can be used to.
[PDF Version]Lead–acid batteries may be flooded or sealed valve-regulated (VRLA) types and the grids may be in the form of flat pasted plates or tubular plates. The various constructions have different technical performance and can be adapted to particular duty cycles. Batteries with tubular plates offer long deep cycle lives.
CTT Technical Ltd are global experts in the manufacture of lead acid batteries. We have a range of products to assist you in setting up your operation and keeping it running like clockwork.
The term advanced or carbon-enhanced (LC) lead batteries is used because in addition to standard lead–acid batteries, in the last two decades, devices with an integral supercapacitor function have been developed.
The behaviour of Li-ion and lead–acid batteries is different and there are likely to be duty cycles where one technology is favoured but in a network with a variety of requirements it is likely that batteries with different technologies may be used in order to achieve the optimum balance between short and longer term storage needs. 6.
Improvements to lead battery technology have increased cycle life both in deep and shallow cycle applications. Li-ion and other battery types used for energy storage will be discussed to show that lead batteries are technically and economically effective. The sustainability of lead batteries is superior to other battery types.
The lead–acid batteries are both tubular types, one flooded with lead-plated expanded copper mesh negative grids and the other a VRLA battery with gelled electrolyte. The flooded battery has a power capability of 1.2 MW and a capacity of 1.4 MWh and the VRLA battery a power capability of 0.8 MW and a capacity of 0.8 MWh.
A battery regenerator is a device that restores capacity to lead-acid batteries, extending their effective lifespan. They are also known as desulphators, reconditioners or pulse conditioning devices.
Steps to Recondition a Lead-Acid Battery Safety First: Wear safety goggles and gloves to protect yourself from the corrosive acid. Remove the Battery: Take the battery out of the vehicle or equipment. Open the Cells: Remove the caps from the battery cells. Some batteries have screw-in caps, while others have rubber plugs.
Lead acid batteries can sometimes sustain damage that cannot be repaired through reconditioning. A common issue is sulfation, where lead sulfate crystals accumulate on the battery plates. Severe sulfation may reduce the battery's capacity beyond recovery, making replacement necessary.
Conventional lead–acid batteries consist of a number of plates of lead and lead dioxide suspended in a cell filled with weak sulfuric acid. Lead oxide reacts with the sulfur and oxygen in the acid to give up an electron, leaving the plate positively charged and producing lead sulfate.
Open the Cells: Remove the caps from the battery cells. Some batteries have screw-in caps, while others have rubber plugs. Drain Some Acid: Use a syringe or dropper to carefully remove some of the acid from each cell. Aim to reduce the acid level to about 50-60%. Add Epsom Salts: Add about 1 tablespoon of Epsom salts to each cell.
lead-acid battery. lead-acid batteries. management of their fleets. WHY MACBATEC IS THE BEST OPTION FOR BATTERY REGENERATION? The efficiency of our battery regenerator, the automation and our continuous technical support, allow us to offer the best battery economy and increased battery life span.
Reconditioning involves removing this buildup and restoring the electrolyte solution. The process includes cleaning the plates, adding distilled water and sulfuric acid, and fully recharging the battery. Reconditioning helps restore capacity and extend the battery's lifespan.
The manufacturer's replacement battery pack was priced at around €100, and a replacement from a third-party supplier was available for around half that price, which is not that bad. From its specification, I was looking for an 18 V replacement pack with a capacity of 2.1 Ah. That meant five cells, probably in the standard. Figure 2a shows that two recesses in the battery lid encroach into the available battery space, ruling out the fitting of two rows of five cells to double capacity. There are, however, more expensive cells in the 18650 format with higher. Building a battery pack from individual cells generally requires a degree of dexterity, electrical expertise, and a spot welder. As you can see from the old unwrapped battery pack in. As already mentioned, the battery compartment cannot accommodate the five cells arranged in rows of two and three to form a W configuration, so I had to find a different pack. With no spot welder to hand, I decided to solder stranded wire directly to the battery terminals. As long as you are careful, this can be done without harming the batteries. Any thermal damage inflicted on the constituent materials of.
[PDF Version]So repairing lithium ion battery packs is the most cost-effective way. It will require a multimeter to check the voltage of each cell one by one and trace the faults that have a lower voltage range below 3.6V on a full charge. After the identification, you must replace it by removing it and soldering it to a new one with the same rating. 4.
If you suspect that your lithium battery is failing, it's best to replace it rather than continue to use it, as a failing battery can pose a safety risk. How Much Does It Cost To Repair A Lithium Battery Pack?
Once you have repaired lithium battery cells by replacing them with new ones, you will have to balance all the cells at the same voltage range. For this purpose, charge the cells one by one with a lithium battery charge with a rating of 3.7 volts. It will fix the lithium battery, help charge it fully, and cut it off naturally. Part 3.
By taking necessary precautionary measures during every stage of the repair process—from initial assessment through final disposal—technicians can help prevent potential injuries caused by mishandling lithium batteries and their components. When it comes to repairing a lithium battery pack, the right tools and supplies are essential.
Swelling is one of the very first signs that a lithium-ion battery cannot be fixed. This swelling is a sure indication the battery has internal damage, such as too much gas or an overheating of the battery. If your battery is swollen, do not use it or charge it. Trying to repair a battery in this condition can cause it to break or even explode.
The simplest and most costly solution is to order a replacement battery pack. But have you considered just replacing the cells in the battery pack? This approach saves money and reduces waste. Furthermore, you can select replacement cells with a larger capacity than the originals. This isn't just a repair; it's an upgrade! It's All Gone Quiet
If your computer won't turn on or shows no activity when you press the power button, this guide offers step-by-step instructions to identify and fix common no power issues on your laptop or desktop.
Check whether your power cable is properly plugged in. If it is, you can now try to switch on your computer. You can also try disconnecting everything (power plug and peripherals). You can now press & hold the power button for some time to remove all remaining charges. 2. Unplug your computer and remove the battery
If your computer has power but does not turn on, it could be due to a hardware failure, such as a faulty motherboard or RAM. It could also be an issue with the BIOS or a damaged operating system. If the power light turns on but the computer does not boot: Check for a BIOS error or hardware fault. Ensure internal components are firmly seated.
This problem actually occurs when there is a problem on your power options, kindly follow the steps below and I hope this helps. Click Choose what power buttons do and make sure that the option "When I press power button" on battery and plugged in is on Shutdown.
The power button is not responding, or power button is sticking. Battery issues: The battery does not charge, drains quickly, or the battery is not recognized. Check Power Button: Press the power button firmly. Sometimes a loose connection may prevent the computer from turning on.
If your PC won't turn on but motherboard light is on, this is probably because you have trouble with your power button. Since not all motherboards have an onboard power button, you can ask the motherboard manual for help to locate the power button first. Then, check if there is a faulty connection or any problems about the case.
If your computer won't turn after a power outage, it might be because of issues with your power source. You can fix this issue quickly by unplugging your computer and removing the battery. Another effective solution is to perform a POST test. A power outage is one of the most dreaded moments in the life of any computer user.
The manufacturer's replacement battery pack was priced at around €100, and a replacement from a third-party supplier was available for around half that price, which is not that bad. From its specification, I was looking for an 18 V replacement pack with a capacity of 2.1 Ah. That meant five cells, probably in the standard. Figure 2a shows that two recesses in the battery lid encroach into the available battery space, ruling out the fitting of two rows of five cells to double capacity. There are, however, more. Building a battery pack from individual cells generally requires a degree of dexterity, electrical expertise, and a spot welder. As you can see. As already mentioned, the battery compartment cannot accommodate the five cells arranged in rows of two and three to form a W configuration, so I had to find a different pack construction. In Figure 5, you can see that. With no spot welder to hand, I decided to solder stranded wire directly to the battery terminals. As long as you are careful, this can be done without.
[PDF Version]It depends on the cause (of battery failure). If the battery is not physically damaged, or not moisture infected, and hasn't aged excessively, The lithium-ion battery can be restored using several techniques like slow charging, parallel charging, using a battery repair device et cetera.
Battery Renew Re-Celling Refurbish Repair SERVICE for Lithium Iron Battery Packs - iTechFixit. No reward points for this product. E-bike/scooter battery pack to rebuild, re-cell, re-new battery for 24V / 36V / 48V / 52V / 60V Lithium ion battery Repair Service. Is your electric bike battery not performing like it used to?
Lithium battery repairs gives broken batteries a new life. If you notice a significant drop in the performance of your devices powered by lithium batteries, such as reduced runtime or slower charging times, it could indicate underlying issues that need attention.
How we do it: We exchange all your battery's internal cell with brand new ones. A-grade battery cells used to recell your battery pack. Your refurbished batteries will look as good as brand new and will work in exactly the same way as it used to. We recell, refurb, and repair Lithium (Li-Ion), Ni-Mh and Ni-Cd battery packs.
Discover professional lithium battery repair services designed to breathe new life into your batteries. Our experts specialise in restoring lithium batteries to their optimal performance, saving you time and money. Say goodbye to premature replacements and hello to sustainable solutions.
Get you battery pack rebuilt with County Battery Services pack rebuilding service. Whether it is Ni-Cd, Ni-Mh or Lithium, we can repair and improve your battery packs to an upgraded standard by exchanging your internal cells to brand new quality battery cells of the same of higher capacity.
Invented in 1859 by French physicist Gaston Planté, the lead-acid battery is the earliest type of rechargeable battery. In the charged state, the chemical energy of the lead-acid battery is stored in the potential difference between the pure lead on the negative side and the PbO2 on the positive side, plus the aqueous. Lead-acid batteries have their own share of advantages. The following are only some of the advantages that this kind of battery boasts: 1. It is not as expensive as the other kinds of batteries. 2. It has over 140 years of development,. The primary reason why lead-acid batteries are widely used in the solar industry is their cost per kWh. The cost per kWh for lead-acid. Our website lists lead-acid batteries from established brands and manufacturers all over the world. As a result, you can expect that the lead-acid batteries.
[PDF Version]
What Safety Precautions Should Be Taken When Handling Sulfuric Acid in Batteries?1. Wear appropriate personal protective equipment (PPE). Work in a well-ventilated area. Use acid-resistant containers for handling. Follow proper disposal methods for sulfuric acid.
Safely storing sulfuric acid is critical because it is highly corrosive and poses potential hazards to both humans and the environment. GSC Tanks prioritizes safety and efficiency in our storage solutions. We outline best practices and guidelines to ensure safe sulfuric acid storage. 1 1. Selecting the Right Tank Material 2 2.
Sulfuric acid, with its widespread industrial use, demands utmost respect for safety protocols at all stages of handling, storage, and emergency response. By implementing the guidelines outlined in this article and fostering a culture of safety, organizations can minimize risks and create safer working environments for their employees.
Batteries should be stored in a well-ventilated area away from heat sources and incompatible materials. Proper containment measures should also be in place to prevent leaks or spills. By following these guidelines for storing and handling battery acid, industrial businesses can ensure workplace safety and compliance with regulations.
Safety Information and Risks Safety should always be a top priority when it comes to batteries, particularly those that contain acid. Battery acid, or electrolyte, can pose risks if mishandled or improperly stored.
These hazards include chemical burns, toxic fumes, and the risk of explosion when in contact with certain materials. Suitable Containers: Choosing the right containers for storing sulfuric acid is fundamental. Materials like high-density polyethylene (HDPE) or glass-lined steel tanks are commonly recommended.
Conducting a Risk Assessment: Regular risk assessments help identify potential hazards and vulnerabilities in the sulfuric acid handling process. This proactive approach allows for the implementation of preventive measures.
How To Repair Solar Battery1. Clean the Battery Terminals Before attempting to repair a solar battery, it is important to clean the battery terminals to ensure a good connection.
It's true; a solar battery can require some maintenance. But the larger question is – how do we do that? Regular cleanups of the battery and its premises, ensuring tight connections, protecting from physical damages, and regular monitoring are essential.
When a battery receives too little energy, it undercharges, often due to insufficient solar input, poor solar panel performance, or an improper charging setup. Undercharged batteries can lead to reduced functionality, shorter lifespan, voltage drops, and energy shortages, ultimately affecting your power supply and system efficiency.
Consistent monitoring and maintenance are key to optimizing solar battery performance. Using tools like battery monitors, a BMS, and cooling systems helps ensure longevity, efficiency, and safe operation for your solar power system. A reliable battery monitor can be invaluable in maintaining solar battery health.
To protect solar batteries from heat damage, it's essential to maintain a cool and well-ventilated environment. Cooling fans, heat sinks, and insulated enclosures can help reduce the risk of overheating and keep your batteries operating within their recommended temperature ranges.
Solar batteries can sometimes have issues with capacity, lifespan, and efficiency, especially if they're low-quality or old. They can also be quite expensive and may not store enough energy to power a home during multiple days of bad weather. Additionally, improper installation can cause safety hazards such as fires or battery damage.
Any malfunction can bring down the entire charging process. Internal damages due to mishandling, manufacturing flaws, sulfate crystal formations, or simply old age can affect a battery's acceptance to charge. Parasitic draw and the impact of sulfation are other common solar battery problems. It's true; a solar battery can require some maintenance.
Phosphoric acid fuel cells (PAFC) are a type of that uses liquid as an. They were the first fuel cells to be commercialized. Developed in the mid-1960s and field-tested since the 1970s, they have improved significantly in stability, performance, and cost. Such characteristics have made the PAFC a good candidate for early stationary ap.
Phosphoric acid fuel cells (PAFC) are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. They were the first fuel cells to be commercialized. Developed in the mid-1960s and field-tested since the 1970s, they have improved significantly in stability, performance, and cost.
This implies that phosphoric acid in the electrolyte layer cannot be easily discharged from the fuel cell together with the cell exhaust gas, although even such minute discharge, results in the degradation of cell performance in the long term. A conceptual working principle is described in Figure 1.
Phosphoric acid as an electrolyte in fuel cells was discovered in 1961 by Elmer Rey and Tanier and became the electrolyte of choice for fuel cells for power plant power generation in the 70s of the 20th century. Phosphoric acid has many advantages as an electrolyte:
At lower temperatures phosphoric acid is a poor ionic conductor, and CO poisoning of the platinum electro-catalyst in the anode becomes severe. However, they are much less sensitive to CO than proton-exchange membrane fuel cells (PEMFC) and alkaline fuel cells (AFC).
PAFC uses phosphoric acid as an electrolyte and generally uses hydrogen as fuel. Hydrogen enters the gas chamber, and after reaching the anode, it loses 2 electrons under the action of the anode catalyst and oxidizes to H +. Anodic reaction: $$ {text {H}}_ {2} to 2 {text {H}}^ {+} + 2 {text {e}}^ {-}$$
Electrolyte is highly concentrated or pure liquid phosphoric acid (H 3 PO 4) saturated in a silicon carbide (SiC) matrix. Operating range is about 150 to 210 °C. The electrodes are made of carbon paper coated with a finely dispersed platinum catalyst. Anode reaction: 2H 2 (g) → 4H + + 4e Cathode reaction: O 2 (g) + 4H + + 4e‾ → 2H 2 O
Lithium is used for many purposes, including treatment of bipolar disorder. While lithium can be toxic to humans in doses as low as 1.5 to 2.5 mEq/L in blood serum, the bigger issues in lithium-ion batteries arise from the organic solvents used in battery cells and byproducts associated with the sourcing and. Much of the world's lithium is extracted by tapping into underground “brine” deposits, pumping water rich in lithium salts into large evaporation ponds. Approximately 500,000 gallons of. Lithium isn't the only problematic metal in lithium-ion batteries. Cobalt, which can constitute a significant amount of the cathode material, is toxic when inhaled or consumed at above. The organic liquids used in most electrolyte formulations are both mildly toxic when ingested and can irritate the eyes and skin. Inhaling their vapors may cause nausea, vomiting,. The cathode material in some high-density lithium-ion batteries includes as much as 80% nickel. Coal-fired nickel smelters, such as the ones found in Indonesia, release carcinogenic.
[PDF Version]Lithium-ion batteries have potential to release number of metals with varying levels of toxicity to humans. While copper, manganese and iron, for example, are considered essential to our health, cobalt, nickel and lithium are trace elements which have toxic effects if certain levels are exceeded .
The remarkable accumulation of Li and heavy metals in anode of spent LIBs was found. Present regulations regarding the management and recycling of spent Lithium-ion batteries (LIBs) are inadequate, which may lead to the pollution of lithium (Li) and heavy metals in water and soil during the informal disposal of such batteries.
Some of these electrolytes are flammable liquids and requirements within OSHA's Process Safety Management standard may apply to quantities exceeding 10,000 lb. Many of the chemicals used in lithium-ion battery manufacturing have been introduced relatively recently.
Whether manufacturing or using lithium-ion batteries, anticipating and designing out workplace hazards early in a process adoption or a process change is one of the best ways to prevent injuries and illnesses.
Lithium-ion batteries (LIBs) present fire, explosion and toxicity hazards through the release of flammable and noxious gases during rare thermal runaway (TR) events. This off-gas is the subject of active research within academia, however, there has been no comprehensive review on the topic.
Exposure to ionic lithium, which is present in both anode material and electrolyte salts, has both acute and chronic health effects on the central nervous system. Lithium isn't the only problematic metal in lithium-ion batteries.
This comprehensive report provides an in-depth analysis of market trends, drivers, and forecasts, helping you make informed business decisions.
As volumes increased, battery costs plummeted and energy density — a key metric of a battery's quality — rose steadily. Over the past 30 years, battery costs have fallen by a dramatic 99 percent; meanwhile, the density of top-tier cells has risen fivefold.
In 2022, the estimated average battery price stood at about USD 150 per kWh, with the cost of pack manufacturing accounting for about 20% of total battery cost, compared to more than 30% a decade earlier. Pack production costs have continued to decrease over time, down 5% in 2022 compared to the previous year.
Just as analysts tend to underestimate the amount of energy generated from renewable sources, battery demand forecasts typically underestimate the market size and are regularly corrected upwards.
The price of lithium-ion batteries has been on a downward trend, reaching a record low of $139 per kWh in 2023 and continuing to decrease into 2024. The reduction in lithium prices, increased production capacity, and technological advancements have all contributed to this trend.
In 2023, IEA reports that the global EV battery demand surpassed 750 GWh, marking a 40% increase from 2022, with EVs contributing to 95% of this growth. The US and Europe witnessed the fastest growth rates among major EV markets, followed closely by China.
In China, battery demand for vehicles grew over 70%, while electric car sales increased by 80% in 2022 relative to 2021, with growth in battery demand slightly tempered by an increasing share of PHEVs. Battery demand for vehicles in the United States grew by around 80%, despite electric car sales only increasing by around 55% in 2022.
Even a relatively small 24V lead-acid battery bank can weight up to half a ton. On the other hand, lithium batteries have a much higher energy density and thus require much less space.
Traditional group 24 lead-acid batteries have the following specifications: The high CCA provides the power to start diesel engines. The size offers the capacity to run accessories. However, lithium batteries are gaining popularity due to their benefits, take GrenerPower 12V100Ah Group 24 LiFePO4 lithium battery for example:
This battery's output voltage range is 21V ~ 29.5V. You can use a 24V DC to AC Power Inverter to convert DC power to 110V or 220V AC power. 4. Use the single 24V lithium ion battery to replace two 12V lead acid batteries connected in serial:
Use the single 24V lithium ion battery to replace two 12V lead acid batteries connected in serial: You may use this single 24V lithium ion battery to replace two 12V lead acid batteries connected in serial. This battery is perfect for devices that need up to 500W power, such as 24V motors in electric scooters and electric wheelchairs.
The capacity of a Group 24 battery can range from 66-110 Ah. It is important to choose a battery with the appropriate capacity for your needs. If you have a vehicle with high electrical demands, such as a large RV or boat, you may want to consider a battery with a higher capacity.
Lithium Group 24 batteries are an excellent option for those looking for a maintenance-free and lighter alternative. Lithium batteries offer several advantages over traditional lead-acid batteries. They are much lighter in weight, which is beneficial for applications where weight is a concern, such as RVs or boats.
However, lithium batteries are gaining popularity due to their benefits, take GrenerPower 12V100Ah Group 24 LiFePO4 lithium battery for example: While lead-acid group 24 batteries are a trusted solution, lithium is an increasingly attractive upgrade for maximum power-to-weight and reduced long-term costs.