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Do RV Batteries Charge When Plugged Into Shore Power

RVs offer the unique opportunity to access many of life’s basic comforts, especially those powered by electricity, when you’re away from home.

So what happens if the RV’s internal batteries run out in the middle of the trip?

Are there any alternatives to a bulky generator?

If you are wondering, “Do RV batteries charge when plugged into shore power?” then, fortunately, the answer is yes.

However, this is not simply a “plug and play” kind of deal.

You will need to turn on your battery first and connect it to a charger or converter before it can start regaining its lost “juice.”

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Below, we will explore a bit more about how RV batteries work and how to ensure they are always ready when you need them.

How Long Does it Take RV Batteries to Fully Charge

When connected to shore power, empty or “dead” RV batteries can take up to 10 hours to charge.

However, this will be affected by the type of battery your RV has, your charger or converter model, and the type of power given by the shore power or local grid.

Most modern RVs use deep cycle batteries.

These batteries can usually be discharged below 50% of their capacity without suffering any significant damage.

They tend to lose less power if they remain unused for a long time.

The capacity in these batteries can be measured with two numbers: amperage (measured in amp hours) and voltage (measured in volts).

Most RV batteries can hold over 100 hours.

Meanwhile, RV appliances are usually designed to work with 12-volt power.

Because of this, RV batteries generally provide 12 volts or come in pairs of 6 volts each.

How does this influence the time it takes for RV batteries to charge fully?

Essentially, the larger the battery, the longer they will take to charge:

  • If you use pair sets of 6-volt batteries and connect them to a high-end Energy Management System, you may be able to charge them more quickly than if you use a single 12-volt battery.
  • Batteries with larger amperage take longer to charge, but you can tweak this by investing more in a high-end charger.
  • If you don’t use a charger and plug the RV battery directly to the shore power, you will only get a “trickle charge,” which can take twice as long.

Read next: What’s The Fastest Way to Charge RV Batteries

How Do I Know When My Batteries Are Charged 

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There are three ways to check whether your RV batteries are fully charged.

You can check the battery panel’s monitor, use a voltmeter, or calculate it depending on the battery’s total capacity and your charger’s speed.

Most high-end batteries come with a battery monitor included.

These will show how much charge is left on their LED screen.

Alternatively, you can plug a handheld voltmeter directly into the battery’s terminals to see how much charge remains.

Voltmeters are harder to use than battery monitors.

Still, they do have one major advantage: they allow you to know the voltage and amperage left, in addition to a simple percentage.

They also allow you to test the energy flow, as well as the amount of stored energy.

However, when dealing with wholly spent or “dead” batteries, you may not get an accurate reading from either a monitor or a voltmeter.

In that case, you will need to divide your charger’s speed (which is in amperages per hour) with the battery’s capacity, which is measured in total amperes.

Make sure you set up an alarm! Overcharging your batteries can also bring about different problems.

Can I Overcharge My Batteries

To put it simply – yes, you can overcharge your batteries, but it is rare.

Most people tend to unplug their RV batteries ahead of time unless they stay at a campsite for several days.

However, it does happen, and it can deplete the battery’s life or reduce its capacity permanently.

How to Know if the Inverter is Charging the Batteries

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You can check if your charger is working using a voltmeter. This is what you need to do:

  • Locate the positive (red) and negative (black) reading wires attached to your voltmeter.
  • Attach them to the lead knobs on top of your battery.
  • Wait for 10 seconds and check the meter’s display.
  • If the value is above 12 volts, then the battery is charging.
  • If the value is below 12 volts, you are undercharging and may need to replace your charger.

Will Leaving My RV Plugged in Too Long Damage the Batteries

Yes, leaving your RV plugged in too long can damage the batteries.

The exact effects will depend on the type of charge you are providing.

Usually, when charging a battery at less than 80% or 90% capacity, most chargers will provide a faster type of charge known as “bulk charge.”

This will allow you to diminish the amount of time it takes to charge your batteries when plugged to shore power.

Bulk charging for too long can overheat the battery or even blow away some of its cells.

If you have a surge protector or energy management system, the power will turn itself off as soon as your batteries are charged beyond 90%.

For that last 10%, you should use your charger on “trickle charge” mode.

This takes much longer, but it will protect your battery cell.

Leaving your RV battery plugged for a couple of extra hours won’t cause any significant damage while on “trickle charge” mode.

However, doing this regularly will slowly chip away at your battery life’s capacity.

Can I Use a 12 V Battery Charger Instead

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Your RV electrical system combines a larger 120-volt AC system with a smaller 12V DC system.

The latter is not very different from a regular car battery.

Meanwhile, shore power and your local electrical grid are created to feed 120-volt systems only.

So, do RV batteries charge when plugged into shore power?

Yes, and this encompasses both the 120V and 12V sections.

This is because your charger often doubles as an inverter, which allows shore power to feed the smaller 12V section of your battery.

However, you cannot feed the 120V section with a simple 12V battery charger.

Moreover, the 120V system is responsible for running all your appliances on deck – so without it, you would only be able to operate essential lighting and fans inside your RV.

Conclusion

It is possible to charge your RV batteries when plugged into shore power.

This may be much more convenient than hooking the RV to a generator when you are on the road.

However, the process to charge your RV batteries may take over 10 hours.

You can use a voltmeter to check if everything is charging correctly – after all, it wouldn’t do to wait until you are leaving the campsite to find out something is wrong!