Because most RVs have two electrical systems – a 12V DC system as well as a 120V AC system – there can be some confusion about some matters related to the two systems and how they function, both together and separately. For example, we’ve often heard the question “Should I disconnect my RV battery when plugged in?” And that’s a great question. So, we thought we’d dedicate a post to the topic in hopes of clarifying a few important points.
Many rigs have an RV battery disconnect switch, and that’s a useful thing. But should you disconnect your RV’s battery when you plug your RV into shore power?
Let’s dig in and find out!
What is an RV Battery?
An RV battery – sometimes referred to as a “house battery” – runs the 12V systems in your RV, providing DC power to your rig’s electronics and devices.
Your RV’s 12V system (your rig’s house battery or battery bank) is capable of providing power to your RV’s lights, 12V outlets, vent fans, slideouts, water pump, and some appliances. That’s true even when you’re parked in the middle of the desert or forest, or on a beach with no way of plugging into a separate power source.
Your RV’s battery bank is one of the greatest things about your rig because it frees you to camp anywhere you want, while still having many modern conveniences that require electricity to function.
What is Shore Power?
The term “shore power” refers to any external power outlet that allows you to access the 120V AC portion of your RV’s electrical system. (AC power is what you typically find in the wall outlets of a house.)
When you have access to shore power, typically via a power pedestal at an RV park or campground, you can run a number of appliances that are more power-hungry, such as your microwave, air conditioner(2), and 120V power outlets.
When your RV is plugged in to shore power, you’re able to power all of the appliances and outlets in your rig.
The same 120V AC power can also be available from an onboard or portable generator. While a “genny” isn’t normally referred to as “shore” power, it does provide the same 120V AC power as you get from plugging into a power pedestal.
Even though shore power is 120V AC, it can also power all of the things your 12V DC system can run. But how can 120V AC electricity power 12V DC accessories?
That’s where your RV converter comes in!
What is the Function of an RV Converter?
As the name implies, the function of an RV converter is to “convert” power. In the case of an RV, that’s converting 120V AC power to 12V DC power. This allows something very important to happen in addition to allowing you to power 12V appliances and devices using 120V AC power.
Your RV converter allows your 12V RV batteries to be charged when plugged into shore power. Those charged batteries are the reason why you’re able to use your RV’s 12V electrical system to power your RV when you’re NOT connected to shore power.
So, this is how you’re able to boondock. It’s why you can run the water pump when you’re parked on the beach, run your vent fans when you’re in a parking lot, and even turn on the lights late at night when you’re camping in the middle of the forest.
So, your RV converter is needed to recharge your batteries when you’re plugged into shore power, and also to power all of the DC components of your RV.
For more in-depth information, see our post on RV power converters.
Is My RV Battery Required to Run the 12V System When My RV is Plugged In?
Thanks to the job your converter is doing, you may not need to have a battery connected to run the 12V system when your RV is plugged into electricity. Some converters can work without one in the system (they separately supply 12V DC to the RV’s electrical system).
However, if you want your RV battery/batteries to charge while you’re plugged into shore power, your battery system does need to be connected.
But it’s also possible for a camper to have a converter in it (or that’s wired in a way) that doesn’t allow the system to work without a battery connected. In these situations, the RV’s 12V electrical loads are wired directly to the battery, and the converter/charger simply provides the power to maintain and/or charge the battery as needed. Your RV converter’s (and/or your RV’s) manual should note whether or not it will continue to supply 12-volt power to the RV’s 12V systems even when the battery is disconnected.
Should I Disconnect My RV Battery When Plugged into Shore Power?
So here we are – back at our original question: “Should I disconnect my RV battery when plugged into shore power?”
And generally, the answer is “No” for short periods of time, (say a month or less). However, for long-term storage, it may be a good idea, or even necessary, to disconnect your RV battery. That’s particularly true if your RV has an old converter/charger (or one that’s cheap/inefficient) that could overcharge the batteries while the rig is stored. In this case, you’d want to prevent overcharging by completely disconnecting (and, ideally, properly storing) the battery.
If you store your RV for a long period of time (over the winter, for example), you may want to completely disconnect your house batteries. In very cold temps, you may even want to store them in a warmer location for the winter.
Even if you have a battery disconnect switch, you’d also want to disconnect your RV battery (at the terminals) under two other circumstances:
- If you don’t have access to shore power to maintain the battery’s charge while the RV is stored. Disconnecting the battery completely
- Your battery disconnect switch doesn’t stop ALL parasitic drains.
Many of your RV’s electronics will continue to draw a small amount of power (known as “parasitic drain”) even when they’re turned off. Disconnecting your battery/batteries will prevent this power draw. Your batteries will still discharge, though more slowly.
You may also have the option to keep your battery charged with the use of a separate smart charger.
But in most situations, your batteries should remain connected when your RV is connected to shore power, so that the battery remains fully charged. That’s how we handle it, since our RV is equipped with a charging system that we can depend on to safely trickle charge our batteries, even over long periods of time… we almost never turn our batteries off or disconnect them.
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John
Wednesday 27th of September 2023
If I change from Lead-Acid batteries for the house battery to LiFePO4 batteries, do I need to be worried about changing the charging unit too? How can I determine if I need to or not?
TheRVgeeks
Wednesday 27th of September 2023
Possibly, John. Depends on the year, make, and model of your charger. Newer RVs typically (though not always) come with units that can handle lithium (as future proofing), but even then they may need a setting changed in order to enable it (not all of them are auto-sensing). So you'd need to identify the make & model # of your charger (or converter/charger) and then look it up to see (1) IF it's capable and (2) how to configure it for lithium.
A couple other items you may need to check are (1) any solar charge controllers if your RV has solar and (2) any connections to a towing vehicle if you have a towable RV. That second one has to do with any 12V charging line that is enabled between your towing vehicle and the RV. IF that's there, you CAN end up draining the RV's lithium battery while you're towing it... instead of charging it, like you'd expect. That has to do with the different charging & float voltages of the two different battery chemistries. Cars/trucks assume lead acid... so their charging & electrical systems are setup for that. Since lithium charges and floats at higher voltages, if there's not the correct protections (diodes or DC-to-DC charging equipment) in place between the truck & trailer, the lithium in the trailer can end up SUPPLYING power to the truck while towing, instead of the other way around.
These same issues can also on all classes of motorhomes, since the alternator is often used to charge the house batteries while driving. So some care/consideration is required, depending on how the RV is setup (not all provide charging of the house batteries when driving).
Hope this all makes sense (and helps)!
Larry
Tuesday 6th of June 2023
I have a 2016 Entegra Aspire, the inverter has been kicking in often lately. Called the manufacturer and we set perimeters on the inside Magnum energy screen and it continued with the same issue. Called Magnum directly and there again set new perimeter and it still kicks in, runs and shuts off.
Is there something else I should be looking at?
TheRVgeeks
Tuesday 6th of June 2023
Sorry to hear about that, Larry. When you say "the inverter has been kicking in often"... do you mean that you're hearing the cooling fan come on and off? Or is the inverter literally kicking on to take over the load for the circuits it manages?
If it's just the first, it could be a faulty temperature sensor... or it's just particularly hot where you are and so the fan has to kick on more often.
If it's the second, it could be something causing the inverter to think that shore power isn't available... so either a faulty circuit breaker that feeds the inverter (check in your RV's circuit breaker box for a 30-amp breaker labeled as "Inverter") or it could be an issue with shore power (possibly voltage dropping due to heavy air conditioner usage by all the RVs in the park). If you have a means of monitoring the voltage on the incoming power, that may help you identify the root cause.
Hope that helps!
Don Curton
Wednesday 8th of June 2022
On my travel trailer, I used to store it plugged into a 120v 15 amp circuit just to charge the batteries (with all appliances off). I would use a regular extension cord with various adaptors to get to the 50 amp RV plug. Unfortunately, the RV converter in my RV is either cheap or defective. It over-charged the batteries, boiled all the fluid out and ruined them. I've since replaced the batteries and installed an aftermarket disconnect switch that completely eliminates parasitic drain. I also use a separately (quality) battery charger hooked directly to the batteries when in storage. I'm very careful to never have both batteries and shore power going at the same time. I also check battery fluid and charge level before and after each trip. If you rely on the stock RV converter to charge your batteries, I'd suggest verifying the amp draw and charge level first because replacing batteries is very expensive.
Pat Parker
Sunday 5th of June 2022
Thanks for the clarification on this issue
Ben Hill
Sunday 5th of June 2022
Do Extended Warranty policies cover DIY repairs or do I have to go to a mechanic.
TheRVgeeks
Sunday 5th of June 2022
Good question, Ben. Unfortunately, it varies A LOT by policy. Some will. Some won't. If they do, they will likely have some fairly strict requirements for documenting the repair (since, otherwise, they wouldn't know if you just bought parts so you'd get the receipt, submitted it for the claim, and then returned the parts). Many handy RVers who prefer to DIY will either "self insure" (i.e. not have an extended warranty at all), or get a lower-level plan to cover catastrophic repairs (engine or transmission failure, for instance) that they don't use for claims for the stuff they can handle themselves. Reduces the cost of the extended warranty plan, but protects you from having to foot the bill for the big stuff.