Tell you the unit conversion in the car's emergency starting power supply

The car emergency starting power supply is a multi-functional portable mobile power product developed in recent years. It can not only support the emergency start of the car, but also can support multiple outputs (such as 5V output, 19V output, etc.). At the same time, the conversion methods of MAH and WH in the car emergency starting power supply have been a question in many people's minds, then you know how to convert the MAH and WH in the car emergency starting power supply? The following small series tells you:

The mAh in an automotive emergency start-up power supply is not an energy unit. It also needs to have the current voltage to be truly energy. Therefore, it can be based on the evolution formula of Ohm's law under the pure resistance circuit: I = Q / t (current = charge, that is, power / time), we can see that Q = It (electricity = current A or mA × time h), so it has Battery capacity in mAh.

The Wh in the car's emergency start-up power supply refers to the amount of voltage, current, and time that are proportional to each other. This amount is called electric quantity. For example, W=Pt (electrical power J=electrical power W or kW×time h), so when the voltage V is described in the battery of the car emergency starting power source, it generally follows Wh in the back, so that it represents how much power the battery can perform. Therefore we can conclude that 1A = 1000mA1W = 1VA. So 1wh=1VAh=1000maVh. If it is a 10V 1000mah battery, we convert it to wh which is 10V*1Ah(1000mah=1Ah)=10wh. As for how much time it can take, we need to look at the power of the appliances.mobile power plant

The content of the above introduction is the conversion method of MAH and WH in the emergency power supply for automobiles. If you have other questions about this area that you do not understand, you can also contact us and we will have professional staff to answer in detail.

Looking at the unlimited possibilities created by China from new energy vehicles

n many people's minds, our country’s level of environmental protection technology is not advanced, but for many visitors who visited the previous session of the High Fair, this understanding was completely subverted. Taking the weaker new energy vehicles of scientific research in our country as an example, the “New Energy Vehicles and Connected Vehicles Special Pavilion” specially set up by the Ministry of Industry and Information Technology, one of the organizers of the High-Tech Fair, revolves around the theme of “Green Intelligence, Smooth Travel to China”, not only It only showed the application of new energy vehicles as a whole and parts technology, and also reflected the unlimited possibilities created by China.mobile power plant

In the “New Energy Vehicles and Vehicle Network Special Feature Pavilion”, BYD Company, a local auto company in Shenzhen, demonstrated that the “Qin” model car equipped with the second-generation DM hybrid has taken the limelight. It is understood that as a hybrid car 0 to 100 kilometers to accelerate only 6 seconds, and the maximum speed of up to 185km / h, while the fuel consumption is only 2L 100 kilometers; even in the pure electric driving state can continue to drive 70KM, to deal with the city business Daily needs such as travel, driving by car are more than enough. This BYD's self-developed car can be called an advanced hybrid car in various parameters.

At the Geely booth, the pure electric vehicle EC7-EV, which is still under development, has attracted the attention of many people. The two-cell battery combination with a mileage of about 165km and a long mileage of 250km is designed. The maximum speed is 200km/h, and the charging speed is up to 80% in 30 minutes! The exhibition of such advanced new energy vehicles will allow viewers to imagine the future without exhaustion. It will also make the audience all wonder that the excitement at the High-Tech Fair is so incredible.

Maybe, the current traditional car industry Lin Lin, the brand impression is deeply ingrained, but with the gradual depletion of oil resources, society is increasingly attaching importance to environmental protection, traditional cars will become outdated, new energy vehicles will become a great success New industry. The infinite possibilities that China will create in the cause of environmental protection will be amplified, extended, and even radiated to foreign countries. It is inseparable from the high-tech fair, which provides a professional platform for docking, exchange, and financing. The last session of the Hi-tech Fair has made everyone lament the advancement of China’s new energy vehicles. It is conceivable that the opening of the 17th Hi-tech Fair will be the time when China’s creation will refresh us again.

High performance flexible super capacitor, wearable device battery future!

Recently, scientists from MIT have developed a new type of flexible supercapacitor based on nanowires, which can be said to be a new generation of ideal energy for fitness trackers and other wearable devices.

Life is particularly important for smart watches and fitness trackers that are becoming more and more popular nowadays, but we all know that these devices are generally not large, which means that their battery capacity will not be too high. The best way is to use a small super capacitor - it can provide fast high power electrical pulse. MIT researchers demonstrated experiments on a variety of materials. Eventually they found that carbon nanotubes and graphene were the best performers, thanks to their larger surface area than other materials—the larger surface area means that Accommodate more ions, which is more energy.mobile power plant

MIT chose germanium nanowires as electrodes for miniature supercapacitors. According to researchers, this supercapacitor has a power density of up to 55 W/cc—3.5 times that of a carbon nanotube supercapacitor. In addition, this capacitor also has the advantage of small size. It is reported that the capacitor does not require any metal support, which will greatly save the space required. The cesium that it uses is a relatively abundant substance in nature, so its cost will be relatively cheap. Imagine how much of this technology will be applied to the car's emergency power supply.

Although the current supercapacitor is only confined to the laboratory, researchers say that they will then design and manufacture a version suitable for mass production.

When will new battery technology be stable and lasting?

In addition to battery life can not meet the user's needs, the stability of the battery seems to be a problem, this can be seen from time to time some of the battery explosion, spontaneous combustion events.

Then, a question worth pondering is when will stable, long-lasting new battery technologies enter the market and enter our lives?mobile power plant

Taking into account the serious mismatch between battery technology and digital device batteries, in order to allow consumers to get rid of the current situation of low battery power, major manufacturers have entered the stage of research and development of new battery technologies. The ultimate goal of manufacturers developing new battery technologies is to apply them to their own products as soon as possible to improve the lifespan and stability of the products. From the current point of view, improved technologies based on lithium batteries are the most likely to enter the market first. .

Some consumers believe that the current endurance of digital products is too short, in large part because of the thin and light body designs that designers use. The limitation of the body size determines that the battery used by the device cannot have a large capacity. Because of this, we have seen many designs that improve the battery life, such as the layered lithium-ion battery design of the LG G2 mobile phone and the rapidity of Qualcomm. Charging technology and so on, these technologies have improved the capacity of the battery to a certain extent, prolonged the use time of the battery, but still cannot solve the problem fundamentally.

When will a stable and lasting new battery technology come?

As mentioned above, the improved technology of lithium batteries will not be able to play a role for a half hour. Since the internal batteries do not work, then we need to work hard from external power sources, such as mobile power. In addition to the traditional mobile power supply, we have previously reported many highly mobile power products, such as the Blue Freedom, which is powered by water in the water, and the high-power emergency power supply for European and American markets.

In addition, there are some solar charging mobile phones that can absorb light for charging in some markets, but in essence, lithium batteries are still used internally.

Of course, it is undeniable that researchers have made some achievements in new battery technologies, such as lithium anode batteries, silicon batteries, and nano-generators that absorb noise for power generation, but these technologies can only work in the laboratory. In order to put it into commercial use, it also needs some reasonable measures.

In other words, it will take 5 to 10 years or even longer for the new battery technology to achieve long-lasting, stable, and easy-to-use results. Until then, lithium batteries will continue to provide life for our digital devices.

When will new battery technology be stable and lasting?

In addition to battery life can not meet the user's needs, the stability of the battery seems to be a problem, this can be seen from time to time some of the battery explosion, spontaneous combustion events.mobile power plant

Then, a question worth pondering is when will stable, long-lasting new battery technologies enter the market and enter our lives?

Taking into account the serious mismatch between battery technology and digital device batteries, in order to allow consumers to get rid of the current situation of low battery power, major manufacturers have entered the stage of research and development of new battery technologies. The ultimate goal of manufacturers developing new battery technologies is to apply them to their own products as soon as possible to improve the lifespan and stability of the products. From the current point of view, improved technologies based on lithium batteries are the most likely to enter the market first. .

Some consumers believe that the current endurance of digital products is too short, in large part because of the thin and light body designs that designers use. The limitation of the body size determines that the battery used by the device cannot have a large capacity. Because of this, we have seen many designs that improve the battery life, such as the layered lithium-ion battery design of the LG G2 mobile phone and the rapidity of Qualcomm. Charging technology and so on, these technologies have improved the capacity of the battery to a certain extent, prolonged the use time of the battery, but still cannot solve the problem fundamentally.

When will a stable and lasting new battery technology come?

As mentioned above, the improved technology of lithium batteries will not be able to play a role for a half hour. Since the internal batteries do not work, then we need to work hard from external power sources, such as mobile power. In addition to the traditional mobile power supply, we have previously reported many highly mobile power products, such as the Blue Freedom, which is powered by water in the water, and the high-power emergency power supply for European and American markets.

In addition, there are some solar charging mobile phones that can absorb light for charging in some markets, but in essence, lithium batteries are still used internally.

Of course, it is undeniable that researchers have made some achievements in new battery technologies, such as lithium anode batteries, silicon batteries, and nano-generators that absorb noise for power generation, but these technologies can only work in the laboratory. In order to put it into commercial use, it also needs some reasonable measures.

In other words, it will take 5 to 10 years or even longer for the new battery technology to achieve long-lasting, stable, and easy-to-use results. Until then, lithium batteries will continue to provide life for our digital devices.

Car battery maintenance instructions during idle period Prevent rust aging

1, to prevent the metal from rust

Corrosion is mainly caused by the combined action of moisture, oxygen, and corrosive substances in the air. Therefore, for long-term parked cars, the metal surface should be kept clean. Parking garages should always be ventilated to keep the relative humidity of the air below 70. Remove dust, dirt, and moisture from the car in a timely manner. The rust-prone parts and the surfaces of the parts should be coated with oil, grease or wrap. The pores in each assembly should be sealed to prevent air, moisture and dust from entering the interior.

2. Prevent deterioration of rubber products

Rubber products on automobiles, such as tires, transmission belts, and dust covers, often undergo aging, swelling, or deformation, resulting in deteriorated performance and shorter service life. The aging of rubber products is mainly due to the fact that rubber is an unsaturated polymer hydrocarbon that easily absorbs oxygen from the air and oxidizes. At the same time, vulcanized rubber has a certain permeability, and oxygen easily enters the interior to cause oxidation. Especially direct sunlight can promote rapid aging of rubber. After rubber products are contaminated with gasoline and engine oil, they will cause volume expansion, loosening gums, and reduced elasticity. In order to prevent the aging of rubber products, direct sunlight and mineral oil contact should be avoided.mobile power plant

3, to prevent the mildew of cotton and linen products

Cushions and rugs are easy to absorb moisture. Especially in wet areas and rainy seasons, it is more susceptible to moisture mildew. Therefore, the owner should always check the cotton and linen products on the vehicle, timely dry it, and keep it dry.

4, to prevent the decline in the anti-knock performance of gasoline

The antiknock performance of gasoline depends on the octane number of gasoline. When the car is parked for a long period of time, the octane number of gasoline will decrease with the loss of light components and the increase of the colloidal content, thereby reducing its antiknock property. Therefore, the gasoline tank must be tightly sealed and the temperature must not be too high. Gasoline storage time is best not to be too long.

5, often check the working condition of the engine

Start the engine at least once a month, idling for 4-5 minutes, and check the operation of the engine. If there is any abnormality, it needs to be adjusted and maintained in time. In addition, always check the battery. The electrolyte level of the battery must be 10-15mm higher than the plate. When it is not enough, distilled water should be added in time. The battery should be kept fully charged and the battery should be charged when necessary.

        6, prepare a car emergency start power.

High environmental requirements Lithium explosion is deeply thought

At present, the hidden dangers of ignition, burning, and even explosion of lithium batteries are still not safe to eliminate. Lithium batteries have a high environmental requirement. A slight environmental discomfort can cause explosions and fires. Therefore, we only need to properly maintain lithium batteries when using electric vehicles. Reduce the probability of lithium battery accidents.mobile power plant

Lithium battery explosion causes

Vehicles in the event of a collision can cause the battery anode and cathode materials to break through the diaphragm, and the energy of the battery can be rapidly recharged to the battery at the instant of braking. (When the electric vehicle brakes, the current during energy recovery can be as high as 250~300 amps. Can not be diverted, it is easy to cause a short circuit.) And other reasons will lead to battery short circuit, temperature rise, causing combustion or even an explosion, In addition, lithium-ion battery electrolyte is organic electrolyte, these substances are more likely to catch fire after contact with air.

       The development of lightweight lithium trams seems simple, but its investment in technology and equipment is very large. The assembly of the normative and systematic requirements of the personnel is high, a little technical errors will lead to battery damage or explosion, so only the domestic comparison Large-scale manufacturers have the strength to formally put into production. There are also only a handful of authorized dealers from countries, provinces and cities. Some small manufacturers with poor technical skills do not strictly control production and assembly, and are extremely prone to accidents.

       Therefore, the high-quality emergency starter power supply reminds you that when using lithium batteries, it must pay attention to its use of the environment, such as the general normal lithium battery temperature below 50 °C, do not invest in the fire, do not short circuit.

Cars in idle period battery maintenance tips to prevent rust aging

1, to prevent metal rust

Rust is mainly caused by the combined effect of moisture, oxygen and corrosive substances in the air. Therefore, for long-term suspension of the car, should keep the metal surface clean. Ventilation should always be kept in the garage where the vehicle is parked, keeping the air relative humidity below 70. Need to promptly remove the car dust, dirt and water. In the rusty parts and parts surface should be coated with oil, grease or oil paper wrap up. Pores in the assembly should be sealed to prevent air, moisture and dust from entering the interior.mobile  power plant

2, to prevent the aging of rubber products deterioration

Automotive rubber products, such as tires, belts and dust cover, often aging, swelling or shape, resulting in deterioration of performance, shorter service life. Such as plastic products aging, mainly due to the rubber is unsaturated polymer hydrocarbons, easy to absorb oxygen in the air and oxidation, while the vulcanized rubber there is a certain permeability, oxygen easily enter the internal oxidation. In particular, direct sunlight, can promote rapid rubber aging. Rubber products are gasoline, oil stains, will lead to volume expansion, gum loose, elastic decline. To prevent the aging of rubber products, direct sunlight and mineral oil should be avoided.

3, to prevent cotton and linen products rotten

Cushion and carpet, are easy to absorb moisture. Especially in wet areas and the rainy season, more susceptible to mildew mildew. Therefore, the owner of the car cotton and linen products should always check, timely drying, keep dry.

4, to prevent the explosion-proof performance of gasoline to reduce

Gas explosion resistance depends on the level of octane number of gasoline. Long-term car parked, the octane number of gasoline will decrease with the loss of light components and the increase of colloidal content, so that its antiknock will be reduced. Therefore, the gas tank must be tightly closed, and to avoid overheating. Gas storage time should not be too long.

5, often check the working condition of the engine

Start the engine at least once a month, idle running 4-5min, check the operation of the engine. If abnormal phenomenon, need to be adjusted and repaired in time. In addition, you should always check the battery. Battery electrolyte level must be higher than the plate 10-15mm, less than the time should be added distilled water, should maintain adequate power, if necessary, the battery should be charged.

        6, prepare a car emergency start power.

Half-way car no electricity, remember not to do it yourself

For car owners, car maintenance is an eternal topic. The weather turns cold, for many electronic components within the car, will form a certain threat, the owner must be careful conservation. Before locking the car, the headlight switch must be turned off, otherwise the electric switch will be damaged. Cold weather, after starting the vehicle, it is best to wait until the vehicle idling stable before driving.mobile power plant

Deal with cold weather, there are many car to be done to maintain, of which the owner often overlooked is the battery. Battery performance will decline as the weather turns cold, energy density will be reduced accordingly, when the battery is more likely to lose electricity. Angie car emergency start power Xie manager reminded the owner, if the battery occurs during traffic losses, be sure to call the rescue hotline, do not do it yourself.

He said: "Two days ago there was a car owner who was on the road when the battery died suddenly. He borrowed a car and planned to charge his battery with someone's battery. As a result, he reversed the positive and negative. Wiring method is the positive then the positive, the negative then negative, but the owner of the positive received the negative, and finally caused the traffic computer was burned, maintenance costs on the million. "Xie manager also said that such reckless bold car owners there are many, Always think they can solve the problem yourself, but in case of operational errors, the loss is difficult to restore. Car circuit is very complex, a minor fault must call 4S shop maintenance hotline, invited professional maintenance personnel to solve.

Car can not hit the fire? Battery "strike" need to be prevented in advance

The main function of the battery is to power the engine ignition system and other electronic lighting devices when the vehicle is on, but some battery owners will be overwhelmed when the battery is out of power, especially in unattended locations. It! So, the owner can prevent battery power loss in advance? Battery sudden encounter "strike" and how to deal with?

In general, the service life of automotive batteries is 2-3 years, when the time reaches two years, when doing routine maintenance, you should pay attention to test the battery, the original car battery can generally use more than 3 years. In the actual car, the battery is quickly led to the main reason is due to improper car owners habits.mobile power plant

To prevent battery loss of electricity to do the following:

1, turn off the owner must remember to turn off the lights, radio, CD, navigation, lighting and various car appliances. If the car does not turn off the lights, overnight, the battery is too tired shock, will eventually strike. Of course, there are a lot of vehicles that already have a lock-up auto-off headlamps, but there are still some cars that require manual turn off of the headlamps, so be careful.

2, to avoid long time parking the car in the open-air parking lot, such as long-term parking, remove the battery to be taken away to prevent icing damage to the battery.

3, the owner in the car and others, listening to music time is not too long, after the modified audio power will be larger than the original, should pay attention to when using.

4, each time you start the engine, but also not more than 5 seconds, and the number of short-term startup should not be too much, to avoid over-discharge battery damage. Avoid multiple starts without interruption, which can result in overheating of the battery.

5, the battery will not discharge for a long time will be self-discharge slowly, until scrapped, therefore, for a long time without the car, will be started from time to time, to charge the battery.

6, the owner should always check the battery accessories and connection lines.

Suddenly encountered "strike" how to deal with?

1, cart "combustion"

Cart start is the most familiar and most effective emergency start method, the owner of the cart before using the method should pay attention to observe the parking location of the vehicle, if the car is uphill, speed is difficult to increase, if there is a downhill to make use of it to increase the speed . In the cart as far as possible not in the vehicles and pedestrians and more sections, so as to prevent the vehicle after the driver accidentally improper strain. It should be noted that the cart "combustion" on the engine, the clutch has some damage, especially in automatic vehicles to avoid using this method to start.

2, take the line start

Batteries need a dedicated battery line, to be thick enough. Take the line, we must pay attention to the correct connection of the positive and negative, in the wiring if there is a small spark pops, is a normal phenomenon. Take the line time to start more than 1 minute, the basic success. If not, you can stay for some time. If you have a car with peers, you can close the two cars until the jumper cable is sufficient to connect the positive and negative poles of the two batteries, and to ensure reliable cable connection.

3, traction start

Traction start than the cart to start a more labor-saving emergency measures. Need to pay attention to is to require two car drivers to determine the contact signal, there is enough understanding, coordinated with the completion.

4, more convenient and efficient car start

Do not overcharge the car battery

Car batteries dead electricity is a normal situation, but is not we all know how to properly charge the battery? Today, Angie car emergency start Xiaobian lead us to take a look at the battery charging precautions and the right way to charge it . Electrolyte proportion drops below 1.2; winter discharge more than 25%; summer discharge more than 50%; dim light; start weakness should be charged. Some owners believe that quick charging can save time, only 3-5 hours. In actual fact, fast charging is only to quickly activate the battery surface, but in fact the battery is not fully charged inside.mobile power plant

In addition to fast charging, there is a slow charging, charging time is 10-15 hours, those who have a deep deficit battery must be slow charging, or charging time is not enough, the lack of charge will directly affect the car's driving performance. Although charging is a fairly easy operation, there are some caveats:

1, to the lead-acid battery, wear protective clothing.

2, charging, the battery can not have sparks near the ban smoking.

3, when charging one or more batteries in parallel, the charger voltage should not exceed 16V.

Battery correct charging method

Today, more and more electric devices on the car, the owner of these electric devices, try not to overload the battery. Battery overload will reduce the battery life. It is important to have the correct battery charge method.

1, the positive battery positive then the positive power supply, negative battery negative then negative power supply.

2, the initial charge controversy two stages: first charge the electrolyte with the initial charge current release bubbles, cell voltage rose to 2.3 ~ 2.4V so far. Then the current is reduced to 1/2 initial charge current, continue to charge the electrolyte to release violent bubbles, compared with the voltage and voltage stability for 3h so far. All charging time is about 45 ~ 65h.

3, the charging process should always measure the electrolyte temperature with half the current, stop charging or cooling method, the temperature control at 35 ~ 40 ℃, the initial charge is completed, if the proportion of electrolyte does not meet the requirements, the application of distilled water or the proportion of 1.4 Of the electrolyte to be adjusted. Adjust and recharge 2h, until the proportion of compliance with the provisions so far.

DOCA teach you how to tell how to start or stop a car

Auto emergency start power is a very popular product in the past few years. It can be used as a starting point for automobiles to provide a supply source for digital products such as mobile phones and laptops. However, it is precisely because of the hot start of the car emergency power sales, the current market emergency start power car manufacturers have sprung up, the quality of their products produced uneven. So how to distinguish between good or bad car emergency start power?

Auto emergency start power

1, batteries.

Battery is an integral part of automotive multifunction emergency power supply, it can be said that the core of the car multifunction emergency power supply. Therefore, its quality is good or bad we distinguish between the car emergency start power is good or bad, we mainly through capacity, operating voltage, charge and discharge cycle life and other aspects to determine its good or bad.mobile power plant

2, safe.

Emergency power car emergency vehicle is an indispensable car care partner, so the difference between emergency start power car is good or bad, first of all have to look at the safety technology does not meet the standard. Because of its safety level is used to distinguish the car emergency start power is a very important criterion, we can look at the car emergency start the power supply has no reverse polarity protection, output short circuit protection, over voltage protection, over current protection A number of global patent security design to determine its security technology does not meet the standard.

3, circuit board.

Everyone should know that when charging a car for starting the emergency power supply, it is generally connected through a circuit board and a wire. Therefore, the quality of a car determines the output quality of a multifunctional emergency power supply of a car. Therefore, we distinguish the car emergency start power good or bad, we must also pay attention to the choice of the circuit board, only a good circuit board can make the car start the emergency power supply maximum performance.

4, conversion efficiency.

Automotive emergency start power, the conversion efficiency evaluation of product conversion ability is more important one of the most important criteria, the conversion rate of the car emergency start power supply can provide users with longer battery life. In the current situation, the conversion rate of domestic auto emergency start power is generally about 80 to 85%.

5, battery capacity.

Although the judge in the automotive emergency start-up power quality is not particularly large part of the weight, but it also belongs to distinguish between the quality of car boot power is a good choice. The size of the battery capacity often determines the number of car starts and endurance time. However, the battery capacity is not to say that the bigger the better, but should look at the performance of various aspects of the product, and then make the choice.

Automotive emergency start power batteries, safety, circuit boards, conversion efficiency and battery capacity, is that we distinguish between the car emergency start power difference between the most important aspects. Of course, there may be some other factors, such as product design and so on.

Caution when using the car emergency power supply for the first time

Auto emergency start power is a relatively hot car sales in recent years, its unique feature is that it can help us start the car when the car is dead, power loss, or other reasons can not start the car. In addition, it can not only start the car, but also for mobile phones, laptops and other products to provide a source of supply. However, since many friends are the first to contact the car emergency start power, so after the purchase, do not know the first time to use emergency power car to pay attention to what? Therefore, Angie car emergency power Xiaobian for the occurrence of this phenomenon, the following for everyone to introduce:

Auto emergency start power

      The first time using the car emergency start the power to note the following:

      1, in general, the regular manufacturers of car emergency start power after the purchase, have some power. Therefore, the first time you use the car emergency start power, the car should be the first emergency power supply after the power is used, and then re-charge.mobile power plant

      2, before using the car emergency start power, to understand the efficiency of the product conversion rate. In general, a good car emergency start power conversion rate is about 80 ~ 85%, if the efficiency conversion rate of less than 80%, then means that the car emergency start power line loss, the battery itself heat.

      3, the car emergency start power USB cable used in the internal resistance can not be too large, otherwise beyond the normal standard USB cable, may cause the car emergency start power charging time is too long or can not be charged. And in use, try not to use the car emergency start power in a dusty, humid environment.

      4, before using the car emergency start power, you need to select the appropriate adapter, the best choice of the adapter with the manufacturer, otherwise there will be unable to charge the phenomenon. Because the car emergency start charging the power supply through the USB cable to digital devices, one end with a USB port to connect the mobile power products, and the other end connected to digital devices, so the other end of the interface must be consistent with the digital device interface, otherwise There is no charge into the phenomenon.

      In the first use of emergency power car emergency, we need to pay attention to the above described matters, as long as the above matters, can effectively guarantee the normal operation of emergency power car. And pay attention to the above matters in use, for extending the life of automotive emergency start power, it is also very helpful.