How to Make an Older RV Boondock-Ready with Just One Battery

You may have read about Mike Wendland’s and Campskunk’s field testing fancy new Roadtrek CS Adventurous XL models with a gazillion amps of lithium-ion batteries and ungodly large inverters and acres of solar panels on the roof with envy. And you may be thinking that boondocking (camping with no hookups) is beyond what you can do with your less sophisticated rig.

Not so!

Sure Mike and Campskunk have some neat features and can pretty much act like they are plugged into Con Edison, an infinite source of electricity, but chances are your current rig can handle boondocking quite well with some relatively simple mods and paying close attention to the resources you do have.

Compartment Onan)

Our Onan generator

Our 20 year old Roadtrek is a perfect example. We have an Onan generator (installed 5 years ago, but the Roadtrek was “generator ready” from the factory) and a single Group 24 battery with a mere 80 amp hours of capacity (20 times less than what Mike has). If you boondock much, a generator is important, but if you only do it occasionally or after a long day of driving, it is not needed.

Trimetric at 100

Trimetric showing battery at 100%

The first thing you should do if you plan to sit in one place without hookups for more than one night is to install a battery monitor.

Those idiot lights on the control panel are not quite worthless, but very close. We highly recommend the Trimetric battery monitor. We wrote an article on how to install one here. Trying to guess capacity of your battery by voltage readings is difficult and since you can’t remove all loads and let it sit for hours (as required for accurate voltage readings) you will have to calibrate to a fixed small load (using a hydrometer). Campskunk did this for his old rig, but it is far easier and more valuable to install a battery monitor.

The battery monitor will tell you the amps going into and out of your battery and will tell you the battery % full. You want to avoid letting your batteries go below 50% (assuming a lead acid battery – whether a wet cell, gel, or AGM). Once you have the monitor installed you can figure out how much power your electrical items are using. Then you can figure out how to minimize the power use. Make yourself a list of how many amps each item uses.

Magnetek Converter (upgraded)

Magnetek Converter (upgraded)

Your camper (ignoring the fancy new technology) has 2 electrical systems, a 120 VAC (volts alternating current) system which is like your sticks and bricks home. And it will have a 12 VDC (volts direct current) which is like your car.

The 12 VDC comes from your house battery. Your house battery is recharged several ways. 1) The camper’s alternator will recharge the battery while you are driving (this is typically the fastest way to recharge). 2) When plugged into shore power the converter/charger or inverter/charger will recharge the batteries. 3) If you have a generator it will supply 120 VAC to the converter/charger or inverter/charger to recharge the batteries. If you have a camper with an older Magnetek Converter consider upgrading it to get a multi-stage charger (see article here).

Once you know what your appliances use in terms of amps you will know what you can operate and how long you can operate it and not drop your battery below 50%. Generally this means avoiding running any 120 VAC appliances by using an inverter. Sure it can be done, but the power required is high. If you need to run the microwave or coffee pot, fire up your generator (or use the propane stove). Immediately switch your fridge to propane if you are not moving. If you have a compressor fridge (12 VDC only) you are going to need more batteries to run it.

LED Light

Convert lights to LED

Another amazing hog is incandescent lights. And even fluorescent lights use more power than LEDs. Convert your lights to LED lights. And when you are boondocking, don’t turn on more than you need.

If your TV /entertainment system is a 120 VAC system requiring an inverter, considering replacing it with a 12 VDC TV with a built in DVD. There are decent TVs built for the trucker market that run off 12 volts and can handle the tremendous voltage range of an automotive system (might be 15 volts from the alternator when driving at freeway speeds). Many of these TVs have built in DVD players which also help reduce power consumption. Our Skyworth TV uses 1.5 amps playing a DVD. Lacking in 12 volt outlets? Add some!

Laptop Charger

12 VDC to 20 VDC adapter for laptop

Our biggest power hog is the laptop computers. Most use 20 volt input. Instead of using an inverter to convert 12 VDC (volts direct current) to 120 VAC (volts alternating current) and then plugging in your laptop cord with its brick that converts the 120 VAC to 20 VDC, you can save a lot by getting an adapter cord that goes from 12 VDC to 20 VDC without as much wasted energy. You can find one on Amazon or eBay for your particular computer model. We make a point of always charging the laptops while driving or when running the generator when we have power to spare. We also wired a USB multiport charger directly into the 12 VDC system for recharging iPod, Kindles and phones. These require a surprising small amount of power to recharge – unlike laptop computers.

Keeping warm. The furnace uses about 3 amps when running. How often it runs is a function of temperature and how well your camper is insulated. Use Reflectix in the windows and consider blocking off part of the camper (especially the cab area) to keep the heat in the area where you are sleeping. Also invest in a warm sleeping bag for winter travels – you will need less heat when sleeping. On our wimpy 80 ah battery we can still manage 2 nights running the furnace with no opportunities to recharge the battery.

Rear Fan - front visible in Mirror

Sirocco Fan

Keeping cool. You aren’t going to have A/C (air conditioning) while boondocking unless you have a generator (or those 1600 amp hours of lithium batteries), so you have to keep cool other ways. Park in the shade. Use your awning to shade the side of your camper.

Use Reflectix in the windows (see article here) – the heat load from sunny windows is huge. Spend the hot days somewhere besides inside your RV. Night is different. The Fantastic Fan in the roof can create a wonderful breeze. You want to be sure a window between you and the fan is open just the right amount to create a good breeze. Too many open windows result in no breeze. Our Fantastic Fan uses 0.9 / 1.5 / 1.9 amps on the 3 settings. Since the fan can be on all the time, that is a big load. Running the Fantastic Fan on high for 12 hours would be 22.8 amp hours – and we only have 40 amp hours to use before we reach the 50% point on our battery. So we seldom run the Fantastic Fan on more than the low setting when boondocking – at least not for long.

We have added some Sirocco Fans which are great for moving air around inside the Roadtrek (see article here). They have 3 settings and timers to shut them off if desired. They use 0.1 / 0.2 / 0.25 amps on their 3 settings. If it is really beastly hot and humid, it is time to go looking for a campsite with hookups!

Recharging your batteries. We really can’t manage more than 2 days without recharging our battery and that is with being careful. Our boondocking typically looks like this. First morning the battery will typically be down to 80-85%. We fire up the Onan to run the Keurig coffee maker and the microwave for breakfast. We also watch the battery monitor it see the amps going into the battery. It starts out around 10 amps but steadily drops. We typically let it run thorough breakfast and clean up. By then the amps going into the battery is down significantly and we shut it off. Getting batteries above 90% via generator is a long process with a generator. This is where solar panels excel. We will run the generator again for a little while at dinner time. But we will often start the evening at a charge level below the first day.

Solar On Top

Our 100 watt solar panel

If you boondock for more than a couple of days at a time (in sunny locations), consider solar. We added a decent basic 100 watt solar system (see article here), and when the sun is bright our battery is charged by 1pm and we can plug in the laptops (on 12 volt adapters) and charge them up in the afternoon while still keeping the house battery at 100%.

Most RVers  have more than 80 amp hours of battery – if we can boondock for a week, so can you. Just  pay attention to how much power you are using and conserve power in appropriate ways.




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  • Eagle Driver

    Thanks Roger. With a dual battery system, any recommendations on how best to monitor battery levels? It is my understanding the Triametric will read amps/volts from one battery, but volts only from a second? Since the dual batteries run in parallel, does the amp/volt portion show the total of the two? Thanks for any advice you can offer.

    Dave
    07C 190P
    Celebration, FL

  • Josiah Hooten

    Thanks this was very helpful, prepping for a summer of work/camp/living in my ’91 dolphin.

  • Ross Broughton

    Great article, thank you!
    We get by just fine with 1 coach battery and 1 solar panel, like your setup . We seldom boondock more than 3 days. Besides, we have to empty our tanks by then anyway. A bunch of extra batteries and panels would be overkill in my opinion . They just add a lot more weight, not to mention the hassle in keeping tabs on everything. And have you heard how loud a 2-3000 watt inverter is in the middle of the night? My 500 watt unit is hardly noticeable, and all we require at night, in both hot and cold climates. And as you say, if weather is really, really nasty, it’s time to find a plug, or turn on the gen. Happy travels!

  • gtegbert

    Roger,
    This is a great review on managing power needs in our RVs. Did the Trimetric come with the 500 amp shunt and cables or did you have to order them as options.