In this column, we will compare the differences of several energy sources on the RV, the sources of supply, the storage methods, the cost and convenience of electricity, gas and fuel, and how to plan how much energy a RV needs to store.
Let's first look at the source and storage of energy supply.
The source of fuel is the simplest. If it is a self-propelled RV, it is to take oil from the vehicle fuel tank. Of course, if it is a trailer, or if the fuel equipment used is different from the fuel used in this car (gasoline RV uses diesel equipment, and vice versa), then you need to buy an additional oil drum. Like this:
Replenishing fuel is naturally to go to the gas station to replenish, which is more convenient.
flammable gas
The fuel gas used in RV is generally liquefied fuel gas, namely propane and butane. Before the popularization of natural gas (methane) pipelines, canned gas-so-called liquefied petroleum gas, also commonly known as gas-was widely used in residential buildings in China (in fact, liquefied petroleum gas is not gas, which is far cleaner and safer than gas). Liquefied petroleum gas is a mixture of propane and butane.
Because the boiling point of butane is -0.5℃, in winter in the north, the liquid can't be gasified normally after being discharged without pressure, so the proportion of propane in liquefied petroleum gas in the north is much higher than that in the south, mainly propane, because the boiling point of propane is as low as -42.06℃. By the same token, the RV in European and American markets uses gas or even pure propane. (Note: The calculation of the density and price of the following liquefied gas is mainly based on the situation in the north.
This kind of liquefied gas is generally stored in large pressure cylinders, with the most typical capacity of 5kg and 10kg, as shown in the following figure-
These cylinders are reusable, and the replenishment method is not as convenient as fuel. After entering the new century, natural gas pipelines are gradually popularized in cities in China, and there are few refueling points in cities, especially refueling points.
But it doesn't mean that liquefied gas is troublesome to use. If you are in a city, you can check the locations of gas filling stations and ventilation stations in advance. In rural areas, because of the low population density, the use of liquefied gas is still very common, so basically every township has refueling and ventilation points.
Liquefied gas is still widely used in township restaurants, so you can also ask the restaurant owner for the number of gas delivery when eating in township restaurants, and wait for the gas delivery person to come and catch your breath while eating.
In addition to traditional large tanks of liquefied petroleum gas, liquefied petroleum gas can also be filled in small bottles used in box furnaces. However, due to the small amount of gas in the gas cylinder of the box furnace, the strength of the gas cylinder is not so high, the weight is light, the manufacturing cost is low, and it is generally not reused, so the unit price is relatively high, but the advantage is that it is more convenient to supplement, and it is available in supermarkets of all sizes.
Of course, this kind of gas cylinder can only be used for cooking, and it is impossible to boil hot water for heating. When cooking, if the traditional liquefied gas stove is replaced by a cassette stove, it is convenient to take it outdoors, eliminating the outdoor kitchen, and can also be used for eating hot pot and barbecue.
electric energy
The electric energy on the RV is complicated, which is divided into three parts: source, storage and output.
Of course, the most traditional source of electricity is connected to the main line, that is, like ordinary families, connected to the 220V municipal power supply pipeline.
For the RV, it is generally through the intelligent hydropower pile in the RV camp that the city power can be received. Of course, if your home is near the parking space on the first floor, you can also draw it out and charge it yourself.
However, this most common way to get electricity from RV in the world is the most "non-mainstream" in China-the reason is that there are too few RV camps in China, and the fees charged by a few RV camps are often too expensive.
In China, although there are few hydropower piles for RV, there are many electric vehicles, and in order to encourage the development of new energy vehicles, the state has built a large number of charging piles in high-speed service areas and other places. In the early days, most of these charging piles were slow charging piles that output 220V alternating current, but in fact, their properties are the same as those of intelligent hydropower piles for RV. The power is still relatively high, generally 7kW, while the intelligent hydropower pile is generally only 4kW. On the one hand, the higher the power, the faster the charging. On the other hand, if necessary, you can use air conditioners and other electrical appliances to charge the battery when there is still residual power.
Some public parking lots are also equipped with such charging piles, so it is very convenient for RVs to park and rest in such places. However, there will be some current noise in the charging pile, and people with shallow sleep may need to avoid spending the night here.
AC slow-filling piles are generally thin, as shown in the following figure-
Charging the RV with a slow charging pile only costs tens of dollars to buy such an adapter-
However, in recent years, in order to improve the charging speed of electric vehicles, there are fewer and fewer AC slow charging in public charging piles, and many of them are replaced by DC fast charging piles. The voltage is 380V according to the national standard, so the RV can't be used directly.
This kind of charging pile is generally thick, as shown in the following figure-
However, this kind of charging pile RV can actually be used, but the equipment investment is high. It takes 3,000 or 4,000 yuan to buy a converter from DC fast charging to AC slow charging. However, after DC to AC, the output power will also drop sharply, only about 6kW, which is not as fast as ordinary AC slow pile filling. Moreover, there will be more loss in the middle, which will lead to an increase in the cost of charging.
However, because the most common charging pile is DC fast charging pile, if the charging power of the car's own engine is not high, it is recommended that the owner of the RV buy one.
Of course, there are also a few new energy self-propelled recreational vehicles that use large-capacity power batteries, which can be directly charged by DC fast charging piles, with high natural efficiency and low loss, and can also make full use of the charging power of DC fast charging piles of 60kW or even higher.
Although these charging methods are widely distributed, they are still inconvenient. If you use fuel or gas, you can replenish hundreds or even hundreds of kWh of fuel in a few minutes, which is equivalent to charging power as high as several thousand kilowatts, much faster.
The charging method of the charging pile is still suitable for simultaneous charging under the condition of long-term parking, but the local environment where the charging pile is located is not so good.
For a self-propelled RV, the most convenient charging method is actually using fuel, that is, driving the generator to charge the battery when the vehicle engine is running.
This is the following thing—
If it is a RV with a hybrid system, the generator may be bigger and more powerful, and the connection with the engine is different, but the principle is similar. That is, the fuel is converted into kinetic energy, which drives the crankshaft of the engine to rotate, and then the crankshaft drives the generator to rotate and generate electricity through some mechanical connection.
The battery and generator on the ordinary RV are 12V, and the charging power is not high, only about 1kW. If you turn on the air conditioner while driving, the power actually used to charge the battery is even less. Therefore, if the RV uses electricity as its main energy source, it will actually take a long time to fill it. But the advantage of this is that you can charge on the road without delay.
However, most RV owners play slowly after retirement, and the daily driving time is generally only 2-4 hours or even shorter. In this case, the charging power is somewhat insufficient.
One of the ways to solve this problem is to choose an RV with higher battery voltage. Although the driving comfort of light truck is poor, one of its major advantages is that it adopts 24V system, and the charging power is above 2kW. At the general pace of play, it is almost enough to generate electricity from the car.
A new generation of RV, represented by Datong RV90, adopts a 48V optical mixing system with a charging power as high as 3.6kW, which can charge the battery at will, and it doesn't matter if you play at a slow pace.
If the power generated by the car is high enough, it will be more convenient to use electricity instead of gas.
Another method is to install solar panels.
After years of development, photovoltaic solar panels are much cheaper than before, and the cost per watt is even as low as 1-2 yuan. Moreover, this is only the initial investment, and the electricity consumption in the later period is actually free.
If the RV uses fuel to generate electricity or electric vehicle charging piles to supplement electricity, the cost per kWh is 1-2 yuan, which means that if the actual efficiency of the hard board is calculated as 40%, it can restore 2500 hours of illumination. If the light shines for 6 hours every day, it is 425 days. If calculated according to 10 year, the RV can exceed this figure for one and a half months every year.
Therefore, if you can really make full use of the RV, even if it is purely based on cost considerations, it should be installed.
And that doesn't count the convenience it brings. As mentioned earlier, charging piles are not convenient to replenish electricity, the generator power is not large enough, and it is not enough to charge by driving. At this time, if you have a 400-watt solar panel, if you are in a sunny field, you can supplement 1 kWh a day. The climate is suitable, and one day is enough when the air conditioner is not turned on. After passing through the hot zone, the extra 1 kwh can not only charge when driving, but also extend the time that the air conditioner can be turned on.
For a trailer, there is no power source for the car, and solar panels are indispensable. Moreover, the trailer roof area is large, and 600-watt or even 800-watt solar panels can often be laid, which has stronger power supply ability. (Generally, the hard board area of 100 watt is about 0.6 square meters. )
Ordinary light passengers and light trucks can generally install 400-500 watts of solar panels, and B-type RVs, mini-trucks and pickup trucks can install 300-400 watts of solar panels, which will be less. If the soft board is replaced, the area that can be laid will be larger than the hard board, but the efficiency is relatively low and the failure rate will increase. Because the roof of the C-type RV is generally large in arc, mainly hard plates, it is more appropriate to install some soft plates.
In the picture below, the solar panels on the roof are hard at the back and soft at the front-
If the power of the self-propelled generator is high, some people may think that the solar panel is not so cost-effective-after all, the 425-day return period calculated earlier is also calculated according to sunny days. In fact, considering the rainy day, it may take more time to return to the capital.
It is worth noting that if solar panels are installed, a ladder must be added at the rear of the car to facilitate the regular cleaning of solar panels on the roof, otherwise the power generation will be greatly reduced, similar to the following figure-
Finally, the simplest method is to install a special generator.
The fuel tank of this generator is separated, so whether the vehicle has fuel or not, it can be directly refueled to generate electricity. If you can't rely on the engine to generate electricity for a long time, you can also use this generator to supplement electricity.
This method is the most flexible, convenient and direct, but the disadvantage is that the noise is generally very loud-usually much louder than the idling noise of the engine; Additional fuel needs to be prepared; In addition, the price of this special generator is not cheap, it costs several thousand yuan.
And if you want a special silent engine for RV, it will cost tens of thousands of yuan, and it will not be too quiet at the same time. I haven't slept well all the time, so I need to recharge my batteries during the day. High-end RVs with built-in generators are often silent generators, or they can take oil directly from the fuel tank. As shown in the figure below:
If you buy an independent generator, you will generally choose gasoline because there will be less noise and smell.
There are also many options for the storage of electric energy. There are three kinds of common car batteries:
Lead-acid batteries, like ordinary fuel vehicles, have the advantage of being very safe, but their energy density is very low.
Colloidal battery, as a variant of lead-acid battery, has better safety and durability, but it is more expensive and has lower energy density, so it is rare in RV.
Finally, lithium batteries are often used as power batteries for electric vehicles. The energy density is much higher, and now the cost per kilowatt hour has been reduced to almost the same as that of lead-acid batteries. In the past, because lithium batteries were expensive and the safety was poor, the original factory on the RV provided less, and later it was installed by itself; Now with the technology becoming more and more mature, the original factory provides more and more. After all, lithium batteries with the same volume and weight can store about 4 times of electricity, which will be much more convenient for RV.
Lithium batteries used in recreational vehicles are all lithium iron phosphate batteries. Although ternary lithium batteries are cheaper, even much cheaper than lead-acid batteries, and have high energy density, they have higher fire risk and are almost never used in recreational vehicles.
Lead-acid batteries and colloidal batteries are all low-voltage batteries of 12V and 24V, while lithium batteries include high-voltage power batteries of 48V or even hundreds of volts besides 12V and 24V.
Although it is also necessary to convert the direct current in the battery into alternating current through the inverter to drive the 220V electrical appliances, the loss of the high-voltage battery is smaller in this process, which is also an advantage of the new energy RV.
After introducing the sources, storage and replenishment convenience of various energy sources, this paper also summarizes several tables to compare the unit energy use cost, the cost and weight of energy storage (which affects fuel consumption and interior space) and the daily consumption of RV (which is used to estimate the required energy storage capacity) of different energy sources.
Use cost comparison:
It can be seen that the cost of directly connecting to the trunk line or using fuel oil and large canned liquefied gas is relatively low. The charging cost of new energy charging piles is relatively high.
Energy storage comparison:
It can be seen that although electric energy is more convenient under certain circumstances (self-supplied cars can be recharged and solar energy can be supplemented for free), in order to store electric energy, it needs to pay much more, which will also occupy the size of the RV and increase the weight of the car.
Finally, we can also calculate the daily energy consumption of general RV and compare the energy consumption of electrical appliances with different functions. On the one hand, we can see whether different equipment is more suitable for electricity, fuel or gas. On the other hand, it can also help us calculate a very important question, that is, how much energy storage capacity the RV needs to plan, especially because energy storage is more expensive and takes up more space and load, so we need to be careful-
In the above table, I marked the most suitable energy form for each electrical appliance in red. The balance scheme in the table is to choose the best energy scheme for each equipment. The gas maximization scheme is to use gas for all available gases.
In addition, the heating part has also been compared twice. Air conditioning heating is aimed at outdoor temperature is not particularly low. For example, air conditioning is enough for heating in winter in the south, while electric oil is aimed at the sub-zero temperature in the north.
The maximum consumption of two workshops is used to analyze the consumption from stopping at night to the rest place of the day and starting again the next morning. Because there will be no more cars and no solar energy in the middle, if we don't consider starting the generator separately, the power needed will be provided entirely by the battery.
As can be seen from the above table, although some consumers think that completely using electricity will reduce the energy complexity and facilitate the calculation of energy endurance, electricity can also be used for driving and solar power generation without tossing a variety of energy sources, which is convenient and safe, but if "heating" is considered, the cost of the all-electric scheme is actually too high, and the electricity used in the car will also be too high. In contrast, gas-heated 10 kg cylinders can last for several days. It's more convenient to use fuel oil to keep warm.
In fact, even a 48V RV like SAIC Datong RV90 has no worries about power consumption, and the heater and water heater still use fuel. Not all depend on electricity.
But if the balance scheme is adopted, in fact, only 6-7 kWh is enough.
If the reader has chosen the form of various devices, he can also use this table to calculate how many batteries he needs to install.
Conclusion:
After reading the contents of this issue and the previous issue, consumers must know very well how affordable and easy to use the RV function configuration provided by the manufacturer. It is precisely because of the importance of these configurations that we should not blindly pursue low prices when buying a car, but really see the price after installing the necessary configurations, and also want to know whether these configurations are practical and easy to use.
Wen | Fish is not a fish.
Figure | Network
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.