What inverters are used in RVs? How to choose the right inverter for your RV and how to install it? This article is a brief RV inverter guide.
You may have noticed that the 120v / 220v wall outlet in the RV only works when plugged into utility power or using a generator. Microwaves and TVs in RVs also work only when the mains is connected.
This means that your RV is not equipped with an inverter.
What is an RV inverter?
The inverter is an integrated electronic module device that can power equipment that normally requires 100 VAC / 120 VAC / 220 VAC / 230 VAC / 240VAC mains power (when no generator is used). If you want to get off the grid, but still want to watch TV or charge your mobile phone, then having an inverter is very convenient. Inverters are usually installed in mid-to-high end RVs, and only serve a small amount of equipment or even all sockets in RVs. If your RV does not have an inverter, then why not add one!
Sounds attractive, right? However, in addition to the simplest requirements, adding inverters is a major change in the way 100vac / 120vac / 220vac / 230vac / 240vac systems work in RVs. In most cases, this is not what you call a "plug and play" upgrade.
How does the RV inverter work? The inverter uses the 12v / 24v battery in the RV to supply power, and then the 12VDC / 24VDC battery is inverted to the 100vac / 120vac / 220vac / 230vac / 240vac voltage required by the socket to provide power for some equipment in the RV. In theory, you can use a large enough inverter to power all your equipment, even air conditioners. However, the power provided by the inverter must not exceed the power of the battery. This requires the cooperation of the battery, otherwise it is easy for the battery to lose power.
The law of current is that increasing the output power from 12v / 24v to 100V / 110V / 120v / 220V / 230V / 240V (a 10-fold increase) will also cause the input amp (current) to increase 10-fold. This means that high-powered devices (such as air conditioners or hair dryers) consume a lot of current, which draws a huge amount of current from the battery.
For example, a 1500-watt device uses 12.5 amps at 120v, so when converting from 12v to 120v, it will draw a minimum of 125 amps from the battery. The power loss is about 10% in the reverse phase. A rule of thumb is that the inverter will consume approximately 10% more battery current than the actual current required for power conversion. This is called inverter efficiency, and the ideal value is 90% -95%.
Under normal circumstances, the RV battery can only provide 50-70 A in one hour, so if you try to do too much work, you will find that the battery quickly runs out of power and becomes a bottleneck. For most RV users, the cost, weight and space required for large battery packs are unaffordable. For cost reasons, this may limit your need to choose more power / power.
How to choose an inverter? Be prepared! Before you start buying equipment, you need to make a lot of planning and decisions. One of the biggest up-front efforts is to determine how much power you expect from the inverter and estimate the inverter capacity required to do so.
Another key decision is how to connect the inverter to an existing system and whether it will be an accessory or a replacement for an existing converter / charger. These decisions can have a significant impact on the cost and effort of the upgrade, so you are likely to decide on a less-than-ideal solution. We need to study them more deeply.
What equipment does it power?
The obvious answer to all existing outlets and equipment. If you want to consider future changes, you need a very large battery capacity, and the cost will continue to increase.
In the other extreme, just add a few sockets that are used only for the inverter. If you only need to charge your phone and watch a little TV, this method is simple and effective.
Between these two extremes, there are various solutions, and depending on your needs, only some of the 100vac / 120vac / 220vac / 230vac branch circuits require power. For example, if you use a refrigerator, you may need to power the refrigerator circuits.
Sometimes the easiest way is to use multiple inverters, such as one for a refrigerator, one for entertainment products (TV, DVD, etc.) and another for kitchen appliances. This allows smaller inverters, which may be located near objects that require power. Multiple inverters can share one battery pack.
How will you rebuild the circuit around the new inverter and connect to the RV circuit? How to supply power to the sockets and equipment to be powered from the inverter module. That will largely depend on the layout of your RV and the equipment to be powered. Think about the equipment you really need to power from the inverter and those areas that need improvement. You may need to redesign multiple times because you also need to consider the size and cost of the battery pack and the cost of the inverter itself.
How to choose the right inverter according to your needs, the main choice of inverter depends on:
1. type 2. Size 3.Power of pure sine wave and modified wave
Let's introduce it in detail:
1. Inverter type The inverter can be an independent unit or an integrated model, and a combined inverter / inverter / charger can be used to replace the existing inverter / charger in the RV.
The integrated type is a good choice if you have an older converter / charger and want to upgrade it, and the integrated type if you are adding the inverter to a modern multi-stage charging system that is large enough Is a good choice. But you need to consider the size of the battery pack.
In either case, installation is the easiest if the device has an internal automatic transfer switch (ATS). This makes it easier to reconnect 100v-120v / 220v-240v systems.
2. Size: How big should the inverter be? The size of the inverter is in watts of output power and is priced accordingly. A 2000 watt inverter can provide up to 2000W of power at a time, provided that you have enough batteries to support it. So what will 2000W do? The standard wall-mounted power socket has a rated maximum current of 15A at 120v, which is equivalent to 1800 watts (maximum). You can find the Watt or Ampere ratings for most devices on the label, or you can find them in the product details on the website. Most RV owners consider 1000-2000 watts to be the appropriate range for their daily needs. However, if you choose to power only devices such as mobile phones and laptops, you may only need 500 watts or less.
For those who want to power more equipment, it is important to understand that a RV with 30A utility power should not exceed 3600 watts, and a RV with 50A utility power should not exceed 12,000 watts. Also, battery size and cost are often limiting factors.
Watt and Ampere
To estimate the size of the inverter, you need to know something about electrical power.
Sometimes you see specifications in watts (watts) and sometimes in amps (amps). The simplest form is Watt = Volt x Ampere. If the label on the device indicates that it uses a maximum current of 10A at 120v, then it is a 1200W device. If the label only says it uses 1200 watts, then you know it uses 10 amps at 120v. Try to estimate the equipment you will use and the equipment that may need to run simultaneously, and then add up the power they require.
Peak power and continuous power The inverter is rated by "peak" and "continuous output". "Peak" is always a higher number, which indicates power in a relatively short period of time, ranging from seconds to minutes (depending on make and model). Some devices consume some extra power when they first start up, such as a microwave oven or anything with a motor or compressor, including a domestic refrigerator. If these devices are to be powered, those inverters with higher peak ratings will better handle these loads.
The continuous output is several hours at a time. Choose an inverter with sufficient rated continuous power to meet your normal power requirements.
3. What does 'modified sine wave' mean? The best inverters are "pure sine waves", which means that they can accurately mimic standard power from the national grid through mains or generators. At the same time, pure sine wave inverters generally have three times the impact power, have a very strong load capacity, and are suitable for many types of equipment.
The modified sine wave is only an approximate value of this standard, and some appliances cannot be used with it well. Some may not work at all. Some devices that may or may not work at all are devices with timers (coffee makers, digital clocks), most electric blankets and heating pads, and any devices with electric motors (power tools, blenders, etc.). Pure sine wave inverters can drive these devices very securely. The modified sine wave inverter is a cost-saving solution developed a few years ago. Pure sine wave inverters were very expensive then. Modern electronic technology has largely overcome the cost difference, and pure sine wave inverters can now be purchased at reasonable prices.
How to install an inverter in a RV The installation of the inverter itself is relatively simple. Basically, the inverter uses a large battery cable to connect directly to the home battery. The complication is routing the inverter's 100v-120v / 220v-240v output power to where it's needed, whether it's a new socket or an existing socket (or both), or a device that needs to be connected to utility power. For existing sockets and equipment, the circuit wires connecting the sockets or equipment need to be disconnected from the existing load center (breaker panel) and connected to the inverter. But you still want these circuits to work on utility power, so you need something to switch between the inverter and external utility power. Normally, the inverter output is connected to a separate switchboard, which in turn feeds power to existing outlets. Power from the main circuit breaker panel is also routed there, and an automatic transfer switch controls which power source supplies power to the outlet at any time. The easiest way to install a new outlet that is always powered only by the inverter. It's as simple as going from an inverter power outlet to an extension cord that requires power.
A more elegant approach is to route at the exit, but this can be a challenge for RVs with thin walls and difficult cabling. Some RV owners use surface mount wiring to avoid this. Be sure to think about how to route in advance.
Points to note during installation:
The wiring must ensure that the mains and inverter power cannot supply power to the same outlet at the same time. Otherwise, it may cause serious damage or even fire, so please do not rely on your own memory judgment or manual switching to prevent this situation. Automatic transfer switches are used to transfer power from the mains to the inverter. Depending on your electrical knowledge and skills, you may need to hand over the installation to a professional who knows both the RV and the electrical wiring.
What is an automatic transfer switch? An automatic transfer switch (ATS) is a device that detects the presence of power on a power source and automatically switches to a backup power source. In this case, your RV mains power is connected to one side of the ATS and the inverter is connected to the other side.
When utility power is provided, ATS selects the power source and "passes" it to various outlets. When there is no utility power, ATS will switch to the inverter and then send it to the outlet.
Inverter reliability Modern inverters are solid-state electronic devices, so they don't wear out and can often be used for many years. However, they are susceptible to high temperatures and humidity. If the inverter is installed in a dusty place, most need a cooling fan. Acid fumes from a fully charged battery can also damage the inverter, so it is best to install the inverter away from the battery or use a sealed battery (such as AGM type).
RV inverter replacement Are there other ways to keep off-grid and get 100v-120v / 220v-240v power? Yes-the most common is a generator. In essence, the generator replaces the power company, and you plug the mains connection line into it. The generator is medium enough to charge the battery and run a few outlets, or it may be large enough (with enough watts) to power the entire RV as usual. Of course, large generators are big, bulky, require fuel, and produce a lot of noise.
Some people may suggest using solar energy, but this is not the case. Solar energy cannot directly power any 100v-120v / 220v-240v equipment, nor can it reliably power 12v equipment. Solar panels generate direct current (DC), the amount and voltage of which vary with the amount of sunlight available. The practical way to use solar energy is to use a solar panel as a battery charger, and use a 12v battery to run the device and power the inverter. However, the power provided is unstable.