With COVID-19, there are a lot of people that have turned to camping for recreation. While some are content to use a tent, a fair number of people are purchasing recreational vehicles (RV) and heading off on road trips. My wife's brother just sold his house and bought a large camper trailer for just such a trip. My cousin is doing the same thing. I have sort of been bitten by the bug as well. I don't plan to convert a Mercedes Sprinter van into a camper but I do love seeing what people have done to create their own tiny homes on wheels.
Yesterday I came across a person that built a very nice RV that seems to be a very comfortable home. I admired all of the thought they put into their build. Unfortunately they ended up doubling their budget for the camper but have something that would sell for 10 times what they paid. However while watching the video I noticed that they over engineered their electrical system and could have saved some significant money. Part of the problem is their mentality of how we use electricity at home vs. while camping and I hope to fix some misconceptions with this post.
A lot of the RVs being built are meant to be used off the grid. That means people want to pull into the forest somewhere and not have to connect to any water or electrical hookups. That is a noble goal and requires careful planning. Thinking of only electricity, this requires several solar panels on the roof combined with a large battery bank. The video I saw yesterday did an excellent job. Then things got expensive for no reason.
Electricity in our homes uses alternating current (AC). There are 2 reasons for this. The first is that it is a more efficient way to get electricity from the power station to your home. The second is that it is easier to fuse. While you can fuse direct current (DC) power systems, large voltages can jump across open circuits as that is what lightning does. We build appliances for our home to run using alternating current because that is what is available. Solar panels and batteries output DC and so one should spend a little time thinking about the losses converting DC to AC as there are some.
While our home appliances run on AC most of our home electronics such as televisions and computers actually run on DC. The power supply in your desktop computer converts the AC power into DC and delivers it to all of the components into your computer. If you look at the power brick associated with your laptop, it will tell you how much voltage AC it expects in and how much it delivers to your actual computer in DC voltage.
Jumping back to the video I watched, they had some massive Lithium-Ion batteries connected to a very expensive 3000 watt pure sine-wave inverter. The purpose of the inverter is to convert the 12 Volts from the batteries into 120 Volt AC power. The fact that it is a pure sine wave means that it closely matches the power supplied in your regular home power outlet. Advertisers for inverters like this say that it is better for sensitive electronics. The truth is that most of your computer power supplies are very robust and will easily convert a non-pure sine wave to the necessary DC voltage. What really needs pure sine wave power are things like electrical motors and refrigerators. Another thing to note is that the pure sine-wave inverter is only 90% efficient at optimum load. That means that the best case scenario is that you are wasting 10% of your electricity.
The thing that really disturbed me about the video is seeing that the inverter had several power strips plugged into it only to have every cord convert that AC power back to DC power. There is also power loss converting AC power to DC. It would be much better to run everything in the camper off of DC power and only use the inverter for things that really need AC power. Let's be honest, if you are building a camper you can find most of your appliances and electronic equipment that will run on DC power. Doing so would allow you to use a less expensive inverter and you could also downsize the number of Lithium-Ion batteries required.
So if you find yourself deciding to build your own camper van, pay attention to your electrical needs. There are a number of products that don't need AC power. You can find fans, lights, refrigerators, and many other electrical devices that run on DC power. If you do a bit of research, you can even figure out how to power your laptop and monitors using DC power. This will save you money in the long run and give you more power given your battery and solar charging capacity.
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