Dear Dave,
I would like to know what kind of battery, inverter, or generator I would need for a few nights off grid in this little ham camper. I would like the option to power a 5000 A/C unit if needed. How is the best way to do that? Mostly just cell phones, lights, normal camp items. No microwave or coffee maker. Maybe a small heater if needed. What would make sense for a tiny camper? Thanks so much! —Tanya, 1967 Serro Scotty
Dear Tanya,
To get the proper setup for going “a few nights off grid” you will need to identify the 12-volt components that you will be using, how long a few nights really is, and a little more information.
The 5000 BTU air conditioner will most likely require a portable generator as it runs on 120-volt power. Although you can use an inverter with soft start RV installed in the AC unit, it would take a very large battery bank to run even a couple of hours. Also, there most likely isn’t that much room in your small trailer.
Identify 12-volt components
Next, you need to identify the 12-volt components, how many you will be using, and how often. Let’s start with the interior lights, which most likely will be incandescent in a 1967 trailer. These draw 1.5 amps per hour. The challenge is determining how many you will be using and how long you will be using them each day. I would suggest switching to LED, which draw .15 amp.
Another factor is the refrigerator, which would have been an absorption model originally and can run off LP with a slight 12-volt draw. However, if it has been swapped out with a residential or 12-volt compressor model, it will draw substantially more 12-volt power.
The original heater running on LP is a big draw of 12-volt power due to the fan motor. I would suggest getting a catalytic heater to supplement the heat, such as the Wave or Mr. Heater, which I use.
There is no “perfect science” when it comes to determining the amount of amp hours you will need, as everyone has a different idea of what they will compromise when dry camping. Other items that will draw 12-volt power include the water pump, roof vents, and any other appliance that runs off LP which also draws some 12-volt power.
Boondocking with solar
I conduct seminars at shows around the country and one of the most popular is the Boondocking—Getting Off The Grid With Solar. You did not mention solar in your question so I must ask how you plan to recharge the batteries. If not solar panels, you will need to start the portable generator or plug the unit in after a certain amount of time.
Getting back to how much battery power you will need, I like to send anyone looking to dry camp to the Go Power! website here. They have a solar calculator, which you can see is a very difficult process going through what components you will be using and how often they will be operating. It is, however, a good lesson is getting acquainted with the components and what they will draw.
What I really like about their site is the easy “Solar Sizing” page in their guide that gives a quick reference to batteries needed, inverter, and solar panels.
According to this template, a small travel trailer going out for 1-3 days would need two AGM batteries, at least, as they can only be drained to 50%, and a 150-watt solar panel. It also recommends a 2000-watt inverter, which I think might be a little high with the components you are looking at.
An upgrade would be to go with two lithium batteries and the 150-watt solar panel. I believe you could get by with a 1500-watt inverter, since you do not have a ton of 120-volt components drawing through the inverter.
You might also enjoy this from Dave
What is the best battery setup for boondocking?
Dear Dave,
Can you help draw up a new house battery system for me. I want to do a lot of boondocking, and don’t want to run the genset a lot to recharge. My house charger is pitiful—undersized. And I’d like to also install PV panels on the roof. I have four 6-volt Trojan deep-cycle batteries, which went south this year and won’t take a charge. Would appreciate all you could do for this disabled veteran. Thank you. Semper Fi. —Bruce, 2015 32-foot Precept Jayco Class A
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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I currently use 2 AGM deep cycle batteries, with 200W of solar panels, a 2000W pure sine inverter, and a 3000W quiet inverter gas generator. My batteries can also charge while my motorhome is running. I have never run short on power, but I am considering doubling my solar panel output JIC. Tanya with her small TT could get by easily with 1/2 of my system.
Thank you, Dave! I think I have been to Go Power’s website in the past. If so, I found it extremely helpful. Thank you for providing the link. I can hardly wait to revisit it. Thanks again. Best wishes and safe travels! 🙂
The Mr. Heater pictured is not a true catalytic heater as it uses Ceramic Tiles heated by burning propane at high temperature. A true catalytic heater uses platinum pads that react propane with oxygen at lower temperature of around 750F-degrees. True catalytic gas heaters are safer than gas heaters that burn propane at high temperature. A true catalytic heater like the Camco “Wave” produce no odor and are virtually silent in operation. The Mr. heater is more like a “flame” heater, producing some odor because combustion is not as complete as a true catalytic heater.
The older ones using ceramic tiles used to be called plaque heaters. And yes, they are just glorified open flame heaters.
Thanks, Dave. I always enjoy your articles. This one was great. I don’t have an RV yet, but still used the Go Solar Calculator and estimated what we would use. It was fascinating to the see the results.
What I’m curious about is the solar generators. What would you need of these to run a small AC?