When you roll up to the RV park and go to plug into shore power, you might ask yourself: do I need to disconnect my battery first? Your RV already has a battery bank after all, is it dangerous to have two sources of electricity at once?
You usually don’t have to disconnect your battery when plugged into shore power. But there are a few unique cases where you might want to disconnect.
First, let’s learn a bit more about your RV’s electrical systems. Then we’ll take a look at when you should disconnect your RV battery.
Your RV’s Two Electrical Systems: AC and DC
Your RV has two separate electrical systems, one for AC power and one for DC power. But what’s the difference?
DC Power
DC stands for “direct current.” With DC power, the electricity flows in only one direction. Most batteries, including the ones in your RV, use DC power. And in most cases, DC power has a voltage of about 12 volts.
Your RV’s DC power system is powered by your RV’s battery bank. This system powers important things in your RV like lights, slideouts, and certain appliances.
AC Power
AC stands for “alternating current.” With AC power, the current changes directions rapidly back and forth 50 to 60 times a second. In North America (and in much of South America), AC power has a voltage of about 120 volts.
AC power is what comes out of the wall outlets in a typical home. Most consumer electronics require AC power to run properly.
Your RV’s AC power system is most commonly powered by a shore power connection. This system can power your consumer electronics and any non-DC appliances in your RV.
Converts & Inverters
There are two other essential components in your electrical system we should mention: converters and inverters. These change the type of electricity from DC to AC or vice versa.
Converters change AC power to DC power, and most RVs come with one installed. When plugged into shore power, your converter can charge your batteries and provide power to your DC devices.
Inverters change DC power to AC power. They don’t come standard on most RVs but are still common and very useful. The inverter lets you use the power from your batteries for your AC devices, even without a shore power connection.
When Should I Disconnect My RV Battery?
So, should you disconnect your RV battery when you connect to shore power? Generally speaking, no.
There are some reasons to disconnect your RV battery, but being plugged into shore power usually isn’t one of them.
When you connect to shore power, your RV’s converter makes use of that power to charge your batteries. It also provides DC power directly to devices, preventing your battery from discharging.
3 Reasons to Disconnect Your Battery
There are only three real reasons you’d disconnect your battery when on shore power:
- Your RV has an old, inefficient converter without overcharge protection. In this case, disconnecting the battery can prevent overcharging.
- You want to charge the battery with a separate smart charger.
- After your battery is charged, disconnecting it while you’re on shore power can slightly improve the battery’s lifespan.
In any other situation, your batteries should stay on with a shore power connection.
But that doesn’t mean there’s never any reason to disconnect your batteries. In fact, many RV batteries come with a battery disconnect switch or have one installed aftermarket. But why would you use a battery disconnect switch?
The main reason is to reduce battery discharge when you won’t use your RV for a while. Your electronics still draw a small amount of charge, even when they’re off. Disconnecting the battery prevents this, although the batteries will still discharge, just much more slowly.
So, if you expect to be away from your RV for a long period, such as when you put it in storage, disconnect your batteries.
Bottom Line: You Don’t Need to Disconnect Your RV Batteries While Plugged Into Shore Power
Your RV’s electrical system can be a bit intimidating and it never hurts to have an abundance of caution. But in this case, there’s no need to worry. There’s no danger or issue with keeping your batteries connected while you’re plugged into shore power.
In fact, it’s perfectly normal, and your RV is probably already equipped to handle this situation. Your RV’s converter will take the AC power from your shore connection to charge your batteries and power your DC devices.
Jennifer lives with her husband in a 29′ trailer in Mexico. She is one half of DashboardDrifters.com and the founder of RVSpotDrop, a web service for full-time RVers. Jennifer Jennings has been RVing for 2+ years and writing about the RV and Van Life for 2+ years. Jennifer specializes in topics such as Lifestyle, van life, campgrounds features, destination features, and product lists.
If your trailer is in storage, but you have solar panels to charge the battery should you still disconnect the battery?
Up to very recently the converter installed on Airstreams was a straight 13.6V converter supplying power to the trailer’s 12V curcuit, including the batteries. Most will use campgrounds with shore power and thus are leaving their batteries on a 13.6 charge, no matter how fully charged they are. This is why I simply disconnect the batteries from the 12V circuit with the “Use/Store” switch when connected to shore power; my 4 year old batteries are like new (based on cell gravity) and I haven’t needed to add distilled water. It’s my MPPT solar controller that takes good care of my 4 deep cycle 6V battery bank.
If your batts are disconnected when plugged into AC , your refrigerator won’t switch to propane without DC power
You would also disconnect your RV battery(s) at the negative – terminal when any welding is being done on any part of the RV. This prevents any stray currents in the frame of the RV from damaging the 12vdc components
I have solar panels, so I leave the battery connected whether it is plugged or not. I unplug it for longer storage and the solar keeps the batteries charged.
My battery had a bad cell in it. The charger continued to charge the battery to the point it nearly caught fire. The battery was so hot I couldn’t touch it. I checked the charger output and voltage regulator and found them to be working properly. Checked the battery and found a bad cell. The battery was three months old. We were sleeping right above it. Thank God the battery was vented to the outside. Had it caught fire we might have been in a bad way.
I was told that my solar panels/controller will continue to charge the batteries even when the battery disconnect switch is off. Sound right?
“After your battery is charged, disconnecting it while you’re on shore power can slightly improve the battery’s lifespan. ”
I wouldn’t recommend doing this. Most converters aren’t designed to handle your 12vdc load. you’ll overheat the converter and could cause issues with 12v components.
Should I disconnect the tow vehicle when I hook up to shore power?