Luckily those of us in the Pacific Northwest that live on the more temperate side of the Cascades can enjoy camping in our RV throughout the year including the cooler fall and winter months.

In addition to soaking in the fall colors and winter scenery, my wife and I enjoy clamming, storm watching, geocaching and sitting around a roaring campfire with friends. If you also enjoy the freedom that comes with boondocking like we do, you will not be hooked up to shore power in a campground which leaves your batteries up to the task of powering your RV.

Boondocking in the Cooler Months

Notice I said batteries, not battery. If you only have one house battery* in your RV you can pretty much forget about comfortably camping without an electrical hook-up as you won’t have enough reserve capacity to keep the systems in your RV operating.

Let’s start with some cold weather battery basics:

FIRST: A fully charged battery has a higher percentage of sulfuric acid than a discharged battery. More sulfuric acid means less water in the battery’s electrolyte. Less water means it is less likely to freeze than a discharged battery. It’s worth noting that a fully charged battery will freeze only if the temperature drops to around 55°F below zero or more, while a discharged battery may freeze around 20°F. This is a big differential and critical if you’re camping in sub-freezing temperatures!

NEXT: You should never let your batteries discharge below 50% of the rated capacity. If they drop below that, recharge them immediately. If you let them discharge to lower than 20% capacity, they will become permanently damaged and never charge to full capacity again.

Now that we have covered the battery basics, let’s look at what can be done to maximize the power that is stored in your batteries when camping in cooler weather.  Battery usage is all about amps out and amps in, if you draw 6 amps out running your furnace, you are going to need a way to put those 6 amps back in or be prepared to head home when your battery bank is at 50% of its rated amperage capacity.

Author's Rather Dirty Battery Bank

There are several ways to put amps back in your battery bank. You can charge them via your tow vehicle or alternator on your motor. This is typically the least efficient but an option every RVer has. You can use solar panels. If your RV is so equipped, make sure to park in a place that maximizes exposure to the winter sun. Equip your RV with a built in or portable generator to charge your batteries. This can be done via the RVs converter / charger by plugging in the RVs electrical shore power cord to the generators 120 volt AC outlet or if the generator is equipped with 12 volt DC output hooking up straight to the batteries. How do you decide which is the best option? Find out what the charge rate ( Note: The charge rate is not always the same as the converter output) is of your RVs converter / charger compared to the DC output of the generator and utilize whichever puts out more amps. If you are going to become a serious winter camper I suggest upgrading to a quality three stage charger with a charge rate of 40 amps or more if you don’t already have one.

Know the Charge Rate of Your Converter Charger

Now that we know our options to put amps back in your battery bank, let’s look at minimizing the amps that are taken out.

The biggest amp draw from your batteries when camping in cold weather will be your forced-air furnace. Research the amperage draw of the furnace in your RV and make a mental note of how often and how long it runs, you can then make an educated estimate on how many amps were drawn out of your batteries and how long your charging source will need to replenish those amps. Example: If your furnace draws 6 amps for every hour it runs and it runs about 30 minutes out of every hour you will need 72 amps per day to recharge your batteries. (6 amps per .5 hours X 24 hours in a day = 72amps / day) If you have a good three stage charger in your RV it may charge at upwards of 40 amps per hour or more, so to put those amps back in you would have to plug your RV into your generator and run the generator for approximately 1.8 hours (72 amps divided by 40 amps per hour = 1.8 hours)

The next largest source of battery drain will be the 12 volt lights in your RV. This can easily be reduced by changing out the incandescent lights that likely came with your RV with LED bulbs which pull 1/10th the power.  Note: Incandescent bulbs draw about 1.5 amps where the equivalent LED pulls about .15 amps. Therefore, two LEDs running for 10 hours would draw 3 amps which would require less than 10 minutes generator run time using the example above.

Finally, you will want to take into account the parasitic loads that will discharge the battery any time you are camping, most are negligible but can add up to an amp or two per hour. Items to investigate are propane gas leak detectors, TV antenna power booster, clocks, stereos and appliance circuit boards. Plus, some refrigerators contain a heat strip to reduce condensation which can be a considerable draw.  An easy way to determine the amp draw of these items is to pull the fuse in the converter and measure the amp draw between the fuse terminals with a volt-ohm meter. Decide if any of these loads can be safely eliminated and add up the remaining balance to determine the daily amperage drain. Then take that number into consideration when charging your batteries.

Determining Parasitic Loads

With a little research and practice you will soon learn how to maximize your RVs batteries while dry camping during the cooler fall and winter months.

*Referring to a standard sized group 24 RV lead acid battery. Caterpillar, Lithium Ion batteries, are a whole other subject.

Dave Helgeson
Author: Dave Helgeson
Dave Helgeson is the MHRV Show Director. He and his wife love to travel across the west in their RV. Dave writes about all things RVing but loves to share destinations and boondocking advice.

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