youtubeForecasters predict La Nina conditions for the Pacific Northwest for the winter of 2020 / 2021 which means colder and wetter conditions. Before winter arrives be sure the proper precautions are taken to protect your RV. In a previous entry we reviewed tips for storing your RV over the winter. One of the tips (#9) addressed protecting your batteries during winter storage. Protecting the batteries is one area RVers tend to overlook when prepping their RVs for storage which can result in ruined lead acid batteries.

In this entry we will look at why this can happen and what you can do to prevent it.

Most RVs have parasitic 12-volt loads like gas detectors, stereo clocks, circuit boards, etc. that are constantly draining your house* battery(s). Even without these loads the house battery (start battery ** too) will self-discharge slowly over time.

* This is the battery(s) that supplies power to the living portion of the RV.

** Motorized RVs (motorhomes) also have a separate battery for starting the engine.

Why is this bad for your batteries while in storage? Well, unless you have the luxury of leaving your RV hooked up to shore power or have an above-average solar charging system, your batteries will become discharged.

Completely discharging your batteries is undesirable for two reasons:

1) Every time your batteries are drained below 50% of rated capacity, it shortens the life span of the battery due to sulfation.

2) The fluids in a discharged battery can freeze as the electrolyte inside the car battery is made up of about 25 percent sulfuric acid and 75 percent water. The acid interacts chemically with lead plates to create electricity. When the electricity is depleted (discharged) mainly water remains making batteries more susceptible to freezing. The expansion of the fluids due to freezing will often cause the plastic housing of the battery to swell and crack, ruining the battery.

Per the folks at Progressive Dynamics“All batteries, regardless of their chemistry, will self-discharge. The rate of self-discharge for lead acid batteries depends on the storage or operating temperature. At a temperature of 80 degrees F. a lead acid battery will self-discharge at a rate of approximately 4% a week. A battery with a 125-amp hour rating would self-discharge at a rate of approximately five amps per week. Keeping this in mind if a 125 AH battery is stored for four months (16 weeks) winter without being charged, it will loose 80 amps of its 125-amp capacity. It will also have severe sulfation, which causes additional loss of capacity. Keep your batteries charged while not in use!”

What you can do to protect your RVs batteries while the RV is stored for the winter:

Keep your batteries charged as a fully charged battery can withstand extreme subfreezing temperatures. This can be done via a battery tender, solar charger or other sources. Note: If you rely on solar to keep your batteries charged be sure the solar panels remain free of snow accumulations.

Use a battery kill switch to eliminate the added battery drain from parasitic loads.

Store your RV in a climate-controlled space that remains above freezing.

Remove batteries from your RV and store them in your garage (provided your garage stays above freezing). Note: Contrary to popular belief, it is okay to store your 12-volt lead-acid batteries on the concrete floor in your garage.

Periodically check the state of charge of your battery(s) over the winter.

Regardless, if you remove your batteries during the off-season storage or keep them in your RV, it is a good time to service your batteries by making sure they are clean and cells are filled to the appropriate levels with distilled water.

Learn how to safely charge and handle lead acid batteries by clicking here.

If you remove the battery(s) from your RV over the winter it is a good idea to take a photo of how the wires are connected before removing them. The photo will serve as reference when you return them to the RV in the spring. When disconnecting a battery always remove the negative lead first. Polarity: On house batteries white is typically the negative and black is the positive. On start batteries black in typically the negative and red is the positive. Here is a short video demonstrating the correct way to remove a battery for winter storage. Here are more tips on how to safely remove a battery.

Take Note of Wiring Connections Before Removing for the Winter

By taking the steps listed above, you can protect your RV batteries from becoming a casualty this winter.

Dave Helgeson
Author: Dave HelgesonEmail: This email address is being protected from spambots. You need JavaScript enabled to view it.
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.


0 #2 Dave 2020-12-01 18:28
The advantage is your batteries stay charged and aren't at risk of freezing. If you have a motorhome keep in mind the converter/ charger won't keep the start battery charged.
The disadvantage is: If your RV doesn't have a quality 3 or 4 stage converter / charger, it is likely to overcharge (boil) your batteries shortening their life span.
0 #1 Andreas Tsirco 2020-11-30 21:54
What are the advantages/disadvatages of leaving your rig plugged in over the winter and letting the rigs charging system keep the batteries charged up?

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