We love to wild camp in our RV, or at least as “wild” as you can call a trip in an RV. Wild camping in an RV simply means living off the grid – no water, no electricity, no sewage/drain dumping and no neighbors of the human variety. Just man, woman, child and dog with nature with one catch – all the creature comforts of home – DirecTV satellite, flat screen television, Mifi cellular internet, full-size residential refrigerator, air conditioning, heat, satellite radio, iMac, Macbook Airs, iPhone, well – you get it. The only thing wild is the location in which we park.
So how to run all of that gear without electricity? To do that, you need a DC-to-AC inverter. DC power comes from “house batteries” which all RVs have. Many newer RVs (especially Class A types) also include inverters – but not all. The inverter simply draws power from house batteries and converts it into 120 VAC power, which is normal household electric. But of course, DC batteries are only storage devices and what goes down (power storage) must come up – i.e. they need to be constantly re-charged.
And this is where it all gets confusing for most people, including me at first.
Quick power and math lesson: some power sources will use amps, others watts or volts. Generally speaking, power used (by appliances) is spoken in either amps or watts. Power generated is usually spoken in amps and occasionally watts. Power sources are almost always referred to in volts (with occasional references to amps). Once you’re beyond source (volts), it’s best to just think and talk in amps – the most common term for power in and power out.
If you get used to knowing that you’re generator is supplying 66 amps of power (per hour is the timeframe noted), then it’s easy to see that a hairdryer using 12 amps is using about 1/5 of your available power. If you use more power than you can generate/create, well then, you’re RVing up a creek without a paddle.
So these power terms, as confusing as they can be, are all related in a simple formula: Volts x Amps = Watts. So you only need to know two of these to know all three because the third can be calculated from the other two. If for example you have a 1500-watt floor heater and want to know how much power (amps) it uses, divide the 1500 by the volts (120 VAC – standard household electric) and you arrive at 13.6 amps).
Most household outlets are connected in a “circuit” which means several outlets and maybe ceiling lamps are connect to a single breaker in your electrical panel. Most breakers for outlets and lights are 15-amp. It’s the same in an RV with one exception, your lights are most likely 12-volts, which means they connect ONLY to your battery, not the 120-volt inverter.
So you can see, a floor/space heater at 1500 watts, is going to hog your 15-amp circuit. If you plugged in another heavy appliance, say a vacuum, you will trip the breaker. And the breaker is a great thing to have because if the breaker didn’t trip, your wiring would melt down and catch the house on fire. So while this all seems like rocket science, there is a method to the madness – your safety.
So you have house batteries and you may even have an inverter which can mimic 120 VAC like your normal household. But that energy comes from batteries just the same as if you don’t have an inverter and only use 12-volt lighting/appliances. And now you need to re-charge. When it comes to re-charging batteries, there are four (4) options:
If your RV is drivable, running the engine will charge the house batteries (depending on configuration) – this is great because as you drive, you charge your engine batteries and your house batteries. Even fifth wheels and campers can have an option to connect to your pulling vehicle’s engine and charge house batteries. While you are driving you can run your inverter and non-heat generating household (120 VAC) appliances. A typical engine alternator will provide 40 to 100 amps and some as high as 200 amps which is great for charging especially on longer drives. But of course, as you’re driving, you’re not going to be doing much laundry or running heat-generating appliances aside from the occasional microwave for the “rolling lunch”.
I haven’t paid too much attention to use while driving because I’m either driving or if Julie is driving, I’m working and connected to my team over the internet. You can probably run the microwave with the inverter while the engine is charging, similar to the generator running, but I’m not too sure of that. It of course, depends on the amps your alternator can create. Even if it can, it is likely more efficient to just run the generator going down the road as we often do in warmer months to run the house A/C. Our engine/dash A/C is not enough to cool the living space where the kids and our dog ride.
SHORE POWER (15-100 amps)
Connecting to “shore power” – available at most campgrounds, plugging into an electric service – will also charge your house batteries. The bonus here is that because your 120 VAC is from the “grid”, you can run almost all appliances (including heat appliances and A/C) depending on the size of the circuit you are connected to: 15-amp, 30-amp or 50-amp.
A 15-amp service is normal, typical household 2 to 3-pronged outlets. This feed is used for bare minimum use, mostly to run the refrigerator (if electric) and charge the house batteries. If you try to run heat-generating appliances or the A/C, you will likely trip the breaker and could cause permanent damage to the RV/appliance.
A 30-amp service is found at most campgrounds and will allow you to run many appliances including heat-generating and A/C plus battery charging. However, you won’t be able to run everything at once, you will have to “load-balance” or juggle priorities to avoid overloading and tripping the breaker.
A 50-amp service is also found at most campgrounds and is the best, largest output you can get. There are actually 2 lines in your heavy 50-amp cord providing a full 100 amps of power. With this connection, you can run most things in your RV simultaneously if you wish (though still not likely). And accordingly, campgrounds charge more for 50-amp service/consumption. One way we’ve overpaid at campgrounds is by always insisting on 50-amp service when, especially in cool areas, we could easily have survived on the cheaper 30-amp service. We are still learning.
Your RV’s power cord, your power needs and your budget will determine which service you use. If you have a 50-amp cord, you can buy converter-cables referred to as “dog bones” that will allow you to downgrade for 30 or even 15-amp service.
GENERATOR (16-67 amps)
Many newer RVs include a generator with either diesel, gas or propane as fuel. Generator outputs varies. Ours for instance is a Cummins Onan 7500-watt generator. So the larger wattage your generator, the more amps it can generate at 120 VAC. Our 7500-watt generator is rated/expected to create 63 amps of power (7500 watts / 120 VAC = 62.5A). In reality we get 66 amps which is great. It’s better than 30-amp shore power but not quite as nice as 50-amp shore power (which is actually, 2 x 50amps = 100 amps). You can run A/C and heat generating appliances at 63-66 amps.
UPDATE: Stupid me – I later learned that our generator is in fact the 8000-watt Onan which /120VAC = 66amps, just as we were getting. Math, it’s constant. I also learned that our 2000-watt inverter is 2800-watt inverter – DOH again. At least I am understating and not overstating. 🙂
The downside to the generator is noise. Even “quiet generators” are still noisier than quite open space in nature. When surrounded by other campers, wild or not, it can be tricky trying to find and follow common courtesy rules of thumb. We all know generators are necessary, but the goal is to run them at reasonable times and as little as needed. Generally speaking, 9am to 8pm is going to be acceptable in most areas of the country. Some areas have posted times as early as 7am and as late as 11pm. We stick to the 9am-8pm anyway, just because. Some people will run them all night in wild camp situations, even with other RVers nearby. Not every RVer is aware that other people exist. And who knows? There may be some RVers who have all-night CPAP needs. You never know without asking.
The more hours your generator runs, the more noise you listen to, the more fuel you burn, the more oil changes you need (generators are just like other engines) and the lower your resale value if you care about such things. You can run it for 2-3 hours a day, usually in 2 or 3 cycles, but the less you need it, the better for everyone.
SOLAR (3-60 amps)
When we bought our new RV last summer, I was hell-bent on installing solar after our first trip in which we wild camped several times. We hated being dependent on our generator, especially around other wild campers who don’t rely on computers/internet and at night and they are happy to read by a flashlight. So I knew we needed more power options and solar may be ideal. But frankly, I didn’t understand it. I barely understood the generator other than press a button and bam – power.
Solar has a lot more variables than other power sources and therefore can be both misleading and confusing.
Edited: I’d like to thank the two gentlemen (Doug Chartrand and Daniel Snow) who email or commented to let me know my power comparisons to shore power were off by a factor of 10. As I said, so many variables, it will challenge you to keep them straight. I hope my updates help you grasp it quicker than I did! 🙂
Most people seem to start with 1 or 2 solar panels and get anywhere from 120-watts to 200-watts on average (10-17 amps). I will write soon about our exact installation with photos (Update: here is that post with details), but for now, our goal was just higher amps. Household batteries charge between 12.2 and 12.8 volts, so we need to use that voltage instead of 120 VAC. Therefore, 870 watts on our new solar panels should generate 70 amps in a perfect world (870 watts / 12.5 average volts = 69.6 amps).
And this is where things get more confusing, solar is imperfect in many ways. Because their source of energy is light from the sun and the sun changes depending on your location and your surrounding (shadows cause a lot of problems/loss), it’s not often possible to achieve 100% or in our case, 69.6 amps. We bought a highly efficient, highly rated panel brand so we expect to do better than most. As we are still installing them, we don’t quite know yet. But I’ve read to expect a 20% loss (or 80% gain depending your optimism/pessimism) so 80% of 69.6 amps = 56 amps at peak sunlight with no shadows. I will explain more about how we optimized our system and what our real-time results are soon.
So if we achieve that goal of 56 amps peak, I will be pretty happy. That would mean we are creating around 1/10th as much energy from the sun in peak hours as we would if we ran our generator.
Update: our install (detailed here) has generated peak amps of over 80-amps, beyond our wildest expectations which is a great tribute to our MPPT solar controller. MPPT stands for maximum power point tracker which gives the amps from the solar panels a boost.
So that’s it – power in a nutshell. Your version of wild camping may be limited use, staying away from the world completely and living old-school when darkness falls – with a flashlight/lantern. Your energy usage would be conservative and needs to recharge would be minimal. A simple solar installation could keep you quiet and humming along. You can hit campgrounds a few times a month for laundry, showers and bulk charging.
If your version of wild camping is more like ours, running a full-sized, household refrigerator plus the occasional appliance, wifi, cellular signal booster and occasional tv/satellite, your energy usage is aggressive and you will need find an aggressive charging solution. Or, become a campground junkie and stay connected to the shore post as often as possible.
For us, our ideal is living quietly off the land, we’re aggressive users and took an aggressive approach to solar as our primary solution knowing we have our generator in a pinch.
Now, we only need to solve our water needs – we’ve made some great gains there and that too will be coming in a new post!