Hello, I am excited to begin my campervan conversion! The difficulty I am running into is how the heck to store enough power to be off-grid most of the time. 2018 Mercedes sprinter van. I will need A/C, fridge, computer for working, lights, plugs, etc. I need to keep expenses low for now, and option to add more later - add solar, more battery storage, etc. Is it possible to plug into shore power say one night, and store enough power for several days after?
Generally a/c is going to be off the table without shore power or a generator, but a swamp cooler uses basically no more power than just a fan. Inverters can also result in fairly big power losses.
A 3-way RV fridge/freezer can be run on propane to conserve power, and if the fridge is mounted on a gimbal like on a boat, you won’t have to level the van.
Computers can vary widely in their power usage. A power frugal laptop should be okay.
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What about a DC powered A/C unit that is small (850btu)? Could that be run on x amount of battery storage? 800 AH?
The specs show that the smallest sprinters come with a 13.5k BTU A/C, medium has 26k BTU, and large has two 26k BTU units, one in the front & one in the rear.
Next we should keep in mind that a traveling vehicle will take much less to cool than a parked vehicle, due to the wind constantly cooling the exterior.
BTU’s can be very misleading, due to so many variables. A BTU (British Thermal Unit) measures the amount of energy used to raise the temperature of 1 pound of water by 1 degree Fahrenheit at sea level. Also noteworthy is that they’re using the term “energy” and not electricity. Energy can come in many forms, and it’s anybody’s guess what type of energy they used. It appears that BTU’s started with steam engines, not electricity, in the mid 1800’s.
So if we’re not at sea level, and the ambient temperate is highly variable, we’re talking about heating/cooling air, not water, and using electricity for the “energy”, just how accurate is it…
Many people believe that CFM (Cubic Feet per Minute) is a far more accurate way to measure it, and indeed CFM plays a huge role in both air heating & cooling. Air circulation plays a huge role in the effectiveness of both heating & cooling, yet the manufacturers choose to use BTU’s. Perhaps to confuse us.
Getting back to power, according to google, 1 Watt is equal to 3.412141633 BTU/h. So a 5,000 BTU a/c would use 1465 watts per hour, which translates to about 145 amps per hour @ 12vdc considering inverter losses. Now multiply that by the number of hours you’ll be running it. Not very practical on battery power, so we’re back to shore power or generator. Some generators can run 8-12 hours on a gallon of gas, but even that can get pretty expensive.
Evaporative coolers, swamp coolers, or Peltier coolers are the most popular alternatives, due to their low power consumption. All three can also be run without electricity if we get creative.
Some choose to follow the weather, go up in elevation, or near water to avoid the heat. These alternatives can work too, although not always convenient.
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I really appreciate this advice! Thank you. I have been thinking that just trying to stay out of the heat as much as possible will be a good idea.
When you’re free to travel, that’s often a good solution, and if it get’s unbearable, go to a campground with power.
If we’re staying stationary for while, it’s often possible to create our own shade if none is available too.
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