I’m using a 2kw battery. I use solar panels or a generator to charge the batteries throughout the day. This is more than enough power for my heat/ac, fridge, freezer, microwave, toaster, laptop, etc.
Smart Power Sources
I have two microgrids inside the camper. One is 120 volts and one is 12 volts. Both of them have automatic relays which switch the power to the most appropriate source. So if shore power (or the generator) is available, then both grids will run off that. If not, then they will automatically switch to the battery bank. I have cigarette lighter ports connected to the 12v grid which power things like lights, wifi, the hotspot, etc.
HVAC runs off the main 120v grid and automatically draws power from the most appropriate source at any given moment as explained above.
12 Volt Microgrid
Let’s go in order of how the power moves through the system. First there is a SA20 port coming in from the Bluetti AC200’s high amperage DC output. This goes to the bottom red input bus in the photo. The ground goes to the ground bus inside the distribution panel.
There is also a 300w 12v shore supply running off shore power if it’s available. This comes in through the single 30a breaker in the photo. From there it runs to the second red input bus near the top of the photo.
Ok now to decide which input bus connects to the distribution panel, I installed a high current relay. This switches automatically between the shore bus or the battery bus depending on whether shore power is available. See the low gauge yellow wire running from the relay to the shore bus? That’s the control wire for the relay, so if there is power on that bus, then the relay switches to that bus.
Now coming out of the relay, the high gauge yellow wire takes the power from whichever bus and sends it to the distribution panel. This means that no matter what the situation is, there is power going to the distribution panel and it all switches automatically.
Then wires run from the distro panel to things like the jacks, ventilation, and eventually the future water pump, and other 12v accessories. It also runs to a double cigarette port shown at the bottom.
One of the cigarette ports has a usb adapter which charges the RavPower USB battery shown to the left. This battery has passthrough so it basically functions as a USB UPS. The RavPower powers the Raspberry Pi (this screen case) and Arduino sensor array at the top of the image. This USB battery also powers a switchable usb hub at the top of the image. This switchable hub controls the internal and external string lights. They could run for a week off this battery without main power.
The arduino constantly measures and records things like temperature, humidity, nuclear radiation, air quality, and other interesting measures. A second array is outside, so this allows us to compare inside/outside data to measure performance and hazards.
There is also a second ground bus at the top which just runs to the distribution panel’s ground bus. This is just to make everything cleaner. You could also just run everything to the same distribution panel ground bus.
Again let’s follow the power as it moves through the system…
The shore power or generator plugs in through a shore socket on the outside of the trailer. From the shore socket, power runs to a power strip which serves as a shore bus. (Yellow in the lower left.) The shore bus has three jobs. The Bluetti AC200 charges from the shore bus. So does my older smaller backup battery (to the right). Second, the shore 12v supply runs off this bus. Third, the shore bus runs into the automatic transfer switch (in front of the Bluetti AC200).
The automatic transfer switch defaults to shore power if available, or runs off the Bluetti AC200 if no shore power is available. The output from this switch goes to the main chassis bus, a special kill-a-watt plugin strip (at the top center) with a screen showing current power usage.
This system allows heating, air conditioning, phone chargers, the microwave, the toaster, etc to automatically run from the most appropriate power source.
The AC200 is also charged by the solar array.This is made up of four 100 watt panels mounted to the roof. I am also experimenting with additional panels which sit on the ground and add on to the capacity of the roof array.
I am using a 1600w Firman generator. This is way more than I need, but it’s a super reliable and highly rated option that’s a lot cheaper than the $1k hondas everyone is using. This just plugs into the same shore power socket that I use when I have access to hookups. The microgrids automatically switch over to draw power there.