Battery Internal Resistance Chart

What is thermochemical energy storage (TCES)?

Thermochemical energy storage (TCES) has attracted significant attention in recent years due to some unique features of the technology such as very high energy density and negligible heat loss during storage. The TCES, however, is still at its early stage of development currently at a technology readiness level of 1–3.

Are hydrogen induced failures a major integrity problem for steel pipes?

At pressure levels in the natural gas distribution network in Europe, hydrogen-induced failures are considered as major integrity problems for steel pipes. Recent attention has been paid to hydrogen embrittlement of APL 5L X52 pipe steel in the service conditions.

What is the thermal efficiency of charge and discharge reaction?

The thermal efficiency of the charge and discharge reaction can reach 85.2% and 94.5%, respectively. However, serious short-circuit will occur in the airflow of both reactors. A large number of granular materials can only contact water vapor through the diffusion of water vapor in the air, thus prolonging the heating and releasing time.

Which flow is best for a fully charging and discharging reactor?

The heat release rate of the parallel flow was faster, and the full heat release of the material in the reactor could be achieved in a shorter time. Therefore, for a fully charging and discharging reactor, no matter how the operating conditions change, the air–water parallel flow has the best promotion on the discharging effect. 4.4. Discussion

Does API 5L X52 pipeline steel reduce elongation after hydrogen absorption?

In this study, we have used the API 5L X52 pipeline steel given by Elazzizi et al. . After hydrogen absorption, a small decrease in the yield stress has been noted (2.5%) as an important reduction of elongation at failure of 38%.

What is a good internal resistance for a battery?

For example, a good internal resistance for a lead-acid battery is around 5 milliohms, while a lithium-ion battery's resistance should be under 150 milliohms. What is the average internal resistance of a battery? The average internal resistance of a battery varies depending on the type and size of the battery.

How can internal resistance dynamics predict the life of lithium-ion batteries?

Internal resistance dynamics reliably capture usage pattern and ambient temperature. Accurately predicting the lifetime of lithium-ion batteries in the early stage is critical for faster battery production, tuning the production line, and predictive maintenance of energy storage systems and battery-powered devices.

What is the internal resistance of a 12V battery?

The normal internal resistance of a 12v battery can vary depending on the type and age of the battery. However, a healthy 12v lead-acid battery should have an internal resistance of around 3-5 milliohms. What is the internal resistance of a bad battery? A bad battery will have a significantly higher internal resistance than a healthy battery.

Why should you use a battery internal resistance chart?

By using a battery internal resistance chart, you can easily monitor the internal resistance of your battery and identify any potential issues before they become a problem. Remember, a lower internal resistance indicates a healthier battery, while a higher internal resistance indicates a bad battery that needs to be replaced.

Do battery internal resistance dynamics correlate with battery capacity?

Conclusions This paper performed a data-driven analysis of battery internal resistance and modeled the internal resistance dynamics of lithium-ion batteries. The analysis demonstrates that battery internal resistance dynamics strongly correlate with the capacity for actual usage conditions even at the early stage of cycling.

How does SoC affect the internal resistance of a lithium ion battery?

However, the SOC has a higher influence on the internal resistance under low temperatures, because SOC affects the resistance value of the battery by influencing the disassembly and embedding speed of lithium ions in anode and cathode as well as the viscosity of electrolyte (Ahmed et al., 2015).

Is internal resistance a limiting discharge rate in a short circuit?

External shorting and nail penetration tests Unlike during a controlled constant current discharge, where increasing internal resistance and polarization dynamics exacerbate heat generation, internal resistance is discharge rate limiting in short circuit scenarios.

What is the difference between ionic and internal resistance at high discharge rates?

Internal resistance at high discharge rates is dynamic and nonlinear. Electrical resistances dictate short circuit current in crucial first seconds. Rapid polarization depletes lithium-ion presence in electrolyte of cathode region. Ionic resistances throttle short circuit heating rates upon cell polarization.

Does high shear stress promote twinning and de-twinning in FCC materials?

A schematic diagram of the grain refinement process involving twinning and de-twinning in FCC materials with low SFEs . In summary, imposed high shear strain and shear stress by SPD promote the formation of nano-twins in FCC materials with low SFEs [86, 210].

How many volts can a solar charge controller handle?

A solar charge controller is capable of handling a variety of battery voltages ranging from 12 volts to 72 volts. As per the basic solar charge controller settings, it is capable of accommodating a maximum input voltage of 12 volts or 24 volts. You need to set the voltage and current parameters before you start using the charge controller.

What are solar charge controller voltage settings?

When it comes to solar charge controller voltage settings there are several voltages involved: Charging Voltages Charge: The Bulk charge Stage consists of approximately 80% of the charge volume, where the charger current remains constant (in a constant current charger) and the voltage increases.

How do I set a solar charge controller?

Set the absorption charge voltage, low voltage cutoff value, and float charge voltage according to your battery's user manual. Adjusting these settings helps prevent battery damage and promotes efficient charging. Start Charging: Your solar charge controller is ready to go once all these settings are adjusted!

What types of batteries can a solar charge controller charge?

In addition to lead-acid and lithium, Morningstar solar charge controllers can also charge nickel, aqueous hybrid ion, and flow or redox flow batteries. Solar charge controllers put batteries through 4 charging stages: Bulk, Absorption, Float, and Equalization. Read more today.

How many charging stages does a solar charge controller use?

Solar charge controllers put batteries through 4 charging stages: What are the 4 Solar Battery Charging Stages? For lead-acid batteries, the initial bulk charging stage delivers the maximum allowable current into the solar battery to bring it up to a state of charge of approximately 80 to 90%.

How do solar charge controllers work?

Solar charge controllers have different settings that need to be adjusted in order for them to work properly. They set up the output parameters of the power so that the battery bank can be charged at the most optimal voltage.

What is the global flexible battery market?

Based on its chargeability the global flexible battery market is segmented into rechargeable and non-rechargeable. The advantages provided by rechargeable batteries will see them hold a greater market share in the global flexible battery market over the given forecast period.

What is the future of flexible batteries?

As the market demand for wearable technologies continues to grow, the future of flexible batteries is promising, and further advances are likely. As with all batteries, one hurdle to overcome is their safe disposal and recycling, which should come as the technology and associated applications become circular.

What are the major challenges in the flexible battery market?

However, the major difficulties in the flexible battery market are the lack of proper fabrication methods and standardization in the development of flexible batteries. These factors are hampering the global flexible battery market during the forecast.

What is the role of flexible batteries in healthcare industry?

The flexible batteries also find application in the healthcare sector in the medical and cosmetic patches being used to track the user's brain, heart, muscle activities, controlling drug flow to the body, etc. These factors collectively will drive the growth of the global flexible battery market over the given forecast period.

What are the key market restraints for the global flexible battery market?

Key market restraint for the global flexible battery market is the high cost associated with the flexible batteries due to the use of the advanced technologies being used in the systems. The other factor which can hinder the growth of the global flexible battery market is the lack of proper standards for the development of flexible batteries.

What is the estimated value of the flexible battery market?

The Flexible Battery Market is projected to reach USD 296 million by 2025 from USD 142 million in 2022, growing at a CAGR of 24.7% during the forecast period. It was observed that the growth rate was 9% from 2021 to 2022. Smart Packaging is expected to account for a high market share of 31%.

Do automatic watches have batteries?

The answer to that question is no. Automatic watches do not have batteries. And the reason for that is that they don't need them. Let's go through the technicality of automatic watches in detail. Automatic movements feature a rotor that is attached to the movement. When the wearer moves his or her wrist, the rotor can rotate freely.

How do automatic watches work?

As a result of ingenious design, automatic watches are powered by the movement of the wearer's body as they move. The natural movement of the arm when the wearer is walking or doing other activities causes a weighted piece inside the watch to fall back and forth, utilizing that kinetic energy to wind the gear train.

What is an automatic watch?

Now, let's start from the very beginning – what is an automatic watch in the simplest explanations? An automatic watch is a mechanical watch that uses energy from the wearer to power itself instead of needing to be manually wound. It has a metal weight called a rotor that spins when you move your hand, and this way winds the watch.

Are all automatic watches the same?

They also require more of your attention. On the other hand, the advantages of self-winding watches often outweigh the negatives. Therefore, it's no wonder they are highly sought-after and appreciated in the watch community. However, not all automatic watches are the same – there are low-quality watches, and there are durable and reliable watches.

Do quartz watches have batteries?

Simply explained, quartz watches are watches that are powered by a battery. A battery powers the watch and gets it to tick. Then we also have automatic watches. Automatic watches are completely mechanical timepieces that have mechanical movements. This brings us to the question: do automatic watches have batteries?

Are battery-powered watches better than automatic watches?

Also, battery-powered watches are more accurate, overall. They will lose or gain a few seconds a month, as any clock is bound to do, though some will lose as little as five seconds a year. By comparison, most automatic watches lose a few seconds every day. After a few weeks, that will result in a noticeable divergence.

What are solid state batteries made of?

Solid state batteries are primarily composed of solid electrolytes (like lithium phosphorus oxynitride), anodes (often lithium metal or graphite), and cathodes (lithium metal oxides such as lithium cobalt oxide and lithium iron phosphate). The choice of these materials affects the battery's energy output, safety, and overall performance.

What materials are used in lithium ion batteries?

Graphite is the most popular material used for the anode in lithium-ion batteries. On the other hand, cathodes are typically made of lithium cobalt oxide, lithium iron phosphate, or lithium manganese oxide. The chemistry of the cathode material directly correlates to the battery's chemistry.

What is inside a lithium battery?

The inside of a lithium battery contains multiple lithium-ion cells (wired in series and parallel), the wires connecting the cells, and a battery management system, also known as a BMS. The battery management system monitors the battery's health and temperature.

What type of electrolyte is a lithium ion battery?

This common type of battery electrolyte is an inorganic compound, commonly referred to as caustic potash. The material is generally harmless as long as we do not ingest it, and it is an ingredient in most soft and liquid soaps. ELECTROLYTES IN LITHIUM-ION BATTERIES Lithium-ion batteries use liquid, gel, or dry polymer electrolytes.

What are the different types of battery electrolytes?

We review common types of battery electrolytes, because different chemistries require different solutions. There are several generic types of electrolytes, which engineers tweak to suit particular applications. Broadly speaking: Electrolytes comprise soluble salts, acids, or other bases. These alternatives may be in liquid gel, or dry formats.

What is a solid state battery?

Solid state batteries utilize solid materials instead of liquid electrolytes, making them safer and more efficient. They consist of several key components, each contributing to their overall performance. Solid electrolytes allow ion movement while preventing electron flow. They offer high stability and operate at various temperatures.

What temperature should a battery be charged?

Batteries can be discharged over a large temperature range, but the charge temperature is limited. For best results, charge between 10°C and 30°C (50°F and 86°F). Lower the charge current when cold. Nickel Based: Fast charging of most batteries is limited to 5°C to 45°C (41°F to 113°F).

How many volts does a battery charge at a low temperature?

At extremely low temperatures, such as -40°C (-40°F), the charging voltage per cell can rise to approximately 2.74 volts, equating to 16.4 volts for a typical lead-acid battery. Conversely, at higher temperatures around 50°C (122°F), the charging voltage drops to about 2.3 volts per cell, or 13.8 volts in total.

How does temperature affect charging and discharging a battery?

Charging and discharging are key processes that can be deeply affected by temperature. Charging: Charging a battery at an improper temperature (either too hot or too cold) can be harmful. Charging in heat can result in overheating and decreased battery life, while cold charging can lead to incomplete charging and internal damage.

How to charge a battery in cold conditions?

Charging a battery to its full capacity in cold conditions requires a higher voltage. It's crucial that the charging voltage adapts to the surrounding temperature of the battery to not only guarantee a complete charge, but also to prevent the risk of overcharging when the temperatures are high.

What temperature should a lead acid battery be charged at?

If the float voltage is set to 2.30V/cell at 25°C (77°F), the voltage should read 2.27V/cell at 35°C (95°F). Going colder, the voltage should be 2.33V/cell at 15°C (59°F). These 10°C adjustments represent 30mV change. Table 3 indicates the optimal peak voltage at various temperatures when charging lead acid batteries.

How does cold weather affect battery charging?

Slower Charging: Cold temperatures also affect the charging rate of batteries. Charging a battery when it's too cold can cause it to charge more slowly or fail to charge altogether. In extreme cases, charging in cold conditions can cause the battery to be damaged permanently, resulting in reduced performance over time.

What are the disadvantages of a short-circuited battery?

Excessive heat generated from a short-circuited cell will pose a fire hazard to the battery pack. One of the disadvantages of having a large number of parallel connections is that a thick connector must be used to carry high current flow into or out of the battery module.

What causes electrical unbalance in a battery pack?

Electrical unbalance of the cells in the battery pack may be caused by different cell SOC, current leakage, different internal resistances or capacity. Only manufacturers with tight quality control can provide high consistency products that require minor balancing efforts.

What happens if a lithium-ion battery is connected parallel?

Uneven electrical current distribution in a parallel-connected lithium-ion battery pack can result in different degradation rates and overcurrent issues in the cells. Understanding the electrical current dynamics can enhance configuration design and battery management of parallel connections.

Are EV batteries a disadvantage?

Currently, the limited capacity of electric vehicle batteries are perceived as a disadvantage to consumers. Moreover, the batteries are the most expensive part of an electric car. Battery companies are looking for ways to keep up with the demand for EV batteries while also staying competitive in this challenging landscape.

What is a distributed battery system?

Distributed battery systems require a different control approach that are more complex than conventional single battery systems. In these scenarios, control structures consist of a Module Control Unit (MCU) and a Battery Control Unit (BCU) that has a master role. A master control unit is required for parallel packs.

Can electrical current dynamics improve configuration design and battery management?

Understanding the electrical current dynamics can enhance configuration design and battery management of parallel connections. This paper presents an experimental investigation of the current distribution for various discharge C-rates of both parallel-connected LiFePO 4 and Li (NiCoAl)O 2 cells.

What is the difference between a positive and a negative battery?

The red positive on a car battery, often labeled with a positive or plus sign, is the positive terminal. The black negative on a car battery, labeled with a negative or minus sign, is the negative terminal. Attach the red cable to the positive terminal and attach the black cable to the negative terminal. 1.

How do you know if a car battery is positive or negative?

You can identify the positive and negative terminals on a car battery by looking for color-coded markings and symbols. The positive terminal usually has a red cover or marking, while the negative terminal is typically marked with black or has a minus sign (-). Color coding: The positive terminal features a red color or cover.

How do you identify a negative terminal on a car battery?

You can recognize a negative terminal on a car battery by its color and symbol, as it is typically marked with black or a shade of blue and features a minus sign (-). The following points detail the characteristics that help in identifying a negative terminal: Color: The negative terminal is generally black.

What color is a negative battery terminal?

The color red and the plus sign for the positive terminal, and the color black and the minus sign for the negative terminal. The negative terminal connects to the vehicle's metal chassis. In this post, I'll show you clearly which terminal is which, how to fit a battery, and what to do if you connect it back ways.

How do you identify a car battery terminal?

Car battery terminals will be marked and color-coded. The color red and the plus sign for the positive terminal, and the color black and the minus sign for the negative terminal. The negative terminal connects to the vehicle's metal chassis.

How do you identify a car battery?

Each step in the maintenance process relies on proper identification to ensure vehicle safety and reliability. A car battery has two terminals. The positive terminal is red and marked with a plus sign. The negative terminal is black and marked with a minus sign.

Are lithium batteries ul 1642 certified?

Traditionally, battery cells have been certified to UL 1642, the Standard for Lithium Batteries. Widely known to apply to lithium-ion batteries, this Standard focused on portable consumer applications. It was not tailored to the needs of motive or stationary applications.

What is ul doing to improve lithium-ion battery safety?

UL and other research organizations are contributing to battery safety research with a focus on internal short circuit failures in lithium-ion batteries. The research is directed toward improving safety standards for lithium-ion batteries.

Is a lithium-ion battery UL certified?

For lithium-ion batteries, the UL designation restricts which trucks the battery is compatible with and requires additional testing of the end product to obtain a full UL Listing. It's important to note that this designation only focuses on the component and not the overall product.

What standards do we cover in our Battery Testing Laboratories?

We cover a wide range of lithium-ion battery testing standards in our battery testing laboratories. We are able to conduct battery tests for the United Nations requirements (UN 38.3) as well as several safety standards such as IEC 62133, IEC 62619 and UL 1642 and performance standards like IEC 61960-3.

Why should you use UL solutions' battery cell certification services?

UL Solutions' battery cell certification services can test to all applicable industry standards to help ensure the performance, reliability and safety of battery cells used in an ever-growing number of products.

What is ul-1973 certification?

serving critical safety protection purposes. This can rail applications (e.g., rail substations)UL-1973 is the ultimate standard for certification of stationary systems as well as the various component packs and

What happens if a battery pack is in series?

For components in series, the current through each is equal and the voltage drops off. In a simple model, the total capacity of a battery pack with cells in series and parallel is the complement to this.

How to complete a battery pack model?

To complete the battery pack model, we need to know how different cell capacities combine to give the overall capacity Q. Going back to our analogy at the start of the post, we can see that the capacity of each cell arrangement in parallel will sum up. But how about those arrangements in series?

How many volts does a battery pack produce?

Portable equipment needing higher voltages use battery packs with two or more cells connected in series. Figure 2 shows a battery pack with four 3.6V Li-ion cells in series, also known as 4S, to produce 14.4V nominal. In comparison, a six-cell lead acid string with 2V/cell will generate 12V, and four alkaline with 1.5V/cell will give 6V.

How to arrange batteries to increase voltage or gain higher capacity?

earn how to arrange batteries to increase voltage or gainhigher capacity:Batteries achieve the desired operating voltage by connecting several cells in series; ea h cell adds its voltage potential to derive at the total terminal voltage. Parallel onnection attains higher capacity by adding up the total ampere-hour (Ah).

What happens if a battery is connected in parallel?

When batteries are connected in parallel, the voltage across each battery remains the same. For instance, if two 6-volt batteries are connected in parallel, the total voltage across the batteries would still be 6 volts. Effects of Parallel Connections on Current

How does a parallel connection increase battery capacity?

Parallel connection attains higher capacity by adding up the total ampere-hour (Ah). Some packs may consist of a combination of series and parallel connections. Laptop batteries commonly have four 3.6V Li-ion cells in series to achieve a nominal voltage 14.4V and two in parallel to boost the capacity from 2,400mAh to 4,800mAh.

Why is graphene a good battery?

Rapid charging and discharging: Graphene's remarkable conductivity enables the swift movement of electrons within a Li-ion battery. This facilitates faster charging and discharging rates, minimizing the time spent waiting for our devices to recharge. Imagine being able to power up your phone in a matter of minutes rather than hours!

Are graphene batteries better than lithium ion batteries?

Faster Charging Times One of the most promising features of graphene batteries is their ability to charge at a significantly faster rate compared to lithium-ion batteries. Graphene's high conductivity allows electrons to move more freely, which speeds up the charging process.

How fast do graphene-based batteries charge?

The big deal is that graphene-based batteries charge really fast. We've been trying out Elecjet's upcoming Apollo Ultra, and it can top up its 10,000mAh capacity in a half hour easily. This really hits home when you realize most batteries at this capacity take a couple of hours to get fully charged.

Can graphene batteries be used in electric vehicles?

One of the most exciting applications of graphene batteries is in the electric vehicle market. Graphene batteries could dramatically reduce charging times, making electric vehicles more convenient and competitive with traditional gasoline-powered cars.

Can graphene batteries power medical devices?

Graphene batteries could also play a role in powering medical devices. Their small size, long life, and fast charging capabilities make them ideal for powering portable medical equipment like pacemakers, insulin pumps, and hearing aids. These batteries would ensure that critical devices are always ready to use, improving patient care.

How do you charge a graphene battery?

For a battery to work, however, the cathode and the anode need to be charged and discharged at different potentials, and the operating voltage window is determined by the difference between the discharge potential of the cathode and the anode. To achieve high capacity, graphene would need to be charged at more than 3 V.

How long does a lithium battery take to charge?

The specific type of lithium battery affects its charging characteristics: Lithium-Ion (Li-ion) Batteries: These batteries typically require 2 to 4 hours to fully charge when using a charging rate of 0.5C to 1C. Li-ion batteries have a lower tolerance for high-speed charging compared to other types.

Should you fully charge a lithium-ion battery?

If you're using a lithium-ion battery for the first time, it's important to fully charge it before use. This will help ensure that the battery performs optimally and lasts as long as possible. Here's what you need to know about charging a lithium-ion battery for the first time.

How to charge a lithium ion battery?

Here are some tips for charging your lithium-ion battery: Make sure you are using a charger specifically designed for lithium-ion batteries. Using the wrong type of charger can damage your battery or even cause it to catch fire. Lithium-ion batteries should be charged between 32°F and 113°F (0°C and 45°C).

How long does it take to charge a battery?

Let the charger run until it shuts off automatically or until you reach the recommended charging time for your particular battery model – usually around 12 hours. Once it's done charging, disconnect everything and put away your tools. Lithium-ion batteries are one of the most popular types of batteries on the market today.

What factors affect the charging time of a lithium battery?

Understanding the charging time of a lithium battery is essential for optimizing its use and maintaining its lifespan. Several factors influence the time required to charge a lithium battery, including battery capacity, charging rate, charging method, and battery type.

What are the best practices when charging lithium-ion batteries?

To ensure optimal performance and safety when charging lithium-ion batteries, adhere to the following best practices: Use Compatible Chargers: Always use chargers designed specifically for lithium batteries to avoid damage and ensure proper charging.

How do you recondition a lead acid battery?

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.

What happens when a lead acid battery is charged?

When charging a lead acid battery, sulfuric acid reacts with lead in the positive plates to produce lead sulfate and hydrogen ions. Simultaneously, lead in the negative plates reacts with hydrogen ions to form lead sulfate and release electrons. This chemical reaction generates electrical energy used to power devices.

Can lead acid batteries be reconditioned?

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.

How do you remove acid from a battery?

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.

How does lead sulfate affect a battery?

During discharge, the process reverses. Lead sulfate on the plates reacts with the electrolyte to regenerate sulfuric acid and lead. Electrons flow through an external circuit, creating electrical power. Over time, lead sulfate buildup reduces the battery's capacity and efficiency.

How do you remove lead sulfate from a cell?

Aim to reduce the acid level to about 50-60%. Add Epsom Salts: Add about 1 tablespoon of Epsom salts to each cell. This helps to dissolve the lead sulfate crystals that have built up on the plates. Refill with Distilled Water: Fill each cell with distilled water to the appropriate level.

What is a 25-watt solar panel?

A 25-watt solar panel can generate approximately 25 watt-hours of energy under optimal conditions every sunny hour. It might seem limited for household appliances. However, a 25-watt solar panel can power various smaller devices and applications.

How much battery do I need for a 25 watt solar panel?

For a 25 watt solar panel, you'd need a 12v 30Ah lead-acid or 12v 20Ah lithium-ion battery. To calculate the size of a battery, multiply the highest number of peak sun hours your location receives (by month, In my case its 6.9 in April) by the solar panel rated wattage and then divide the value by 12 for 12v battery

How does a 25W solar panel work?

At daytime the 25W solar panel charges a 12V battery inside the control unit, which then provides power to 4 x 5W 12V LED lights connected via front sockets on the control unit. In addition, there's a standard 5V USB socket for charging mobile phones and USB compatible devices.

How many amps can a 25 watt solar panel produce?

Under optimal conditions, a 25-watt solar panel can produce just a little over 2 amps of current at 12 volts.

Can a 25W solar panel charge a laptop?

But if you have a 25w solar panel most probably you'll use it to charge your cellphone, laptop, or maybe a few other small appliances. so i recommend a jackery explorer 240 portable solar generator which will make your life easier.

Do I need an inverter for a 25W solar panel?

But you wanna run a small appliance so you'll need an inverter or if you're using multiple 25w solar panels your total output will be higher. so a 50w pure sine wave inverter is recommended for 25w solar panels, keep in mind that the inverter will cause a 15% of loss in current when converting DC into AC.