How to Wire RV Batteries?

When RVing, a lot of us wish to live off the grid.

Outside in nature, away from the people (and noise! ), savoring the serenity, stillness, and wide-open areas However, obtaining adequate electricity is the main challenge for us contemporary RVers (apart from access to water).

We have appliances like refrigerators, computers, water pumps, phones, and lights, all of which need electricity.

The first step is to have an effective battery bank that is big enough for your power requirements.

No matter whatever RV battery or batteries you choose, it is obviously not a good idea to let them entirely discharge.

For instance, lithium-ion batteries can only be depleted by 20% before harm is evident, but lead-acid batteries may become damaged when they are down by half.

Additionally, even if you use a solar panel or generator to charge your RV batteries every day, you’ll still want to have a big supply of power on hand so you can use as much energy as you need during the day and night without seriously harming your batteries.

Adding extra batteries to your RV to power it is the simplest way to solve this issue.

But how easy is it to do this?

I’ll go through the advantages and disadvantages of both a 12V battery setup and a 6V battery setup in the sections below, as well as how to properly connect numerous batteries to both.

12 Volt Battery Setup

RVs, along with travel trailers, truck camps, vans, and fifth wheels, need 12-volt electricity to operate while not attached to an electrical hookup.

The most common form of battery used in RVs is a 12 Volt marine deep cycle battery, which is easily accessible in shops wherever you go.

When purchasing from a dealer, they will often parallel-connect one or two 12 Volt batteries.

Additionally, 12V batteries often cost cheaper than 6V ones, and connecting two 12V batteries together to enhance the amp hours is fairly simple.

The measurement that provides you a general indication of how much storage an RV battery has is amp hours.

You may buy deep cycle RV batteries with much more or less amp hour storage, however the majority of RV/Marine deep cycle batteries can store between 35 and 70 amp hours.

I would advise a battery setup with at least 70 amp hours if you camp without a connection on the weekends or if you are a full-time RVer who often camps in campsites or RV parks with hookups, whether it be with one or two 12V RV batteries.

6 Volt Battery Setup

You may be asking why a 6V battery setup would be necessary for your RV.

After all, 12V electricity is what RVs need to operate.

There are two methods to connect batteries, series and parallel, which I’ll cover in more detail below.

Since you are enlarging the batteries while maintaining the same voltage, wiring a 6V battery in parallel is equivalent to connecting 12V RV batteries.

In contrast, series wiring increases voltage while maintaining the same amp hour capacity.

You need at least two 6 Volt batteries to power an RV since it requires 12 Volts to operate.

Future additions of batteries will also require that they be added in pairs.

A 6V 225ah AGM deep cycle RV battery weighs around 71 lbs, and most RVers link their two 6V batteries in series.

Combining two of these batteries yields a 12V battery with 225ah capacity.

When expressed in watt-hours, this may be easier to comprehend.

You may get a battery’s watt-hour capacity by dividing the total voltage by the amp hours.

Two 12V RV batteries with 100ah each have 2,400 watt-hours, compared to one 12V RV battery with 100ah, which has 1,200 watt-hours.

A single 6V 225ah RV battery will have 1,350 watt-hours of power.

While the amp hours on the 6V battery are substantially higher than those on the 12V battery, you may have noted that the watt-hours are quite close.

Simply said, this is because you multiplied by 6 instead of 12.

As a result, 2,700 watt-hours will be generated by two 6V batteries of 225ah.

How to Properly Connect Several 12 Volt Batteries to an RV?

Actually, wiring more than one 12V RV battery to an RV is not that complicated, and you normally don’t need to hire an expert.

There might be a few ways for things to go wrong, however.

Your goal is to properly parallel connect the 12V batteries such that the power is distributed equally across all of the batteries.

Your batteries will last longer and perform better as a result of this.

To connect the RV batteries, you will first need the correct wiring.

Copper wire in the range of 6-4 AWG is advised, with 4 AWG proving to be the most efficient due to its low resistance, which improves the efficiency of power transmission from the batteries.

You can’t go wrong with a substantial length of red and black 4 AWG copper wire with the proper sort of battery terminal connections, however each battery setup may vary based on the size of the batteries you’re using and the location where they will be kept.

The majority of deep cycle RV batteries may be used with the Windy Nation 4 AWG Cable Kit, which also includes ample wire length for common connections.

However, it’s recommended to purchase extra to be safe if you plan to wire up more than 4 RV batteries or if there will be a lot of space between the batteries connected.

A crimping tool, such as this IWISS Cable Lug Crimping Tool, is also necessary to properly wire your batteries.

Although you may try the wiring without it, it will be difficult to get tight or secure connections.

This can result in increased resistance and eventual battery failure.

Parallel wiring: Positive terminals are combined with other positive terminals and negative terminals are combined with other negative terminals when connecting batteries in parallel.

This implies that with the same voltage, you may build a bigger battery.

Although it is feasible to combine batteries using the parallel approach, you cannot mix batteries of different voltages, and I would also advise against combining batteries of various sizes and ages.

Because you want the voltage to remain constant, you must wire 12 Volt batteries in parallel.

In contrast, you want to boost the voltage with 6V batteries.

The wrong method to parallel connect 12V batteries: If the load cables that link the batteries to your RV are attached to the same battery, you’ve done it wrong.

The first battery in the line receives inconsistent pressure, whereas the final battery in the line receives insufficient pressure.

The original batteries will deplete much more quickly than the other batteries if you parallel connect your RV batteries in this manner.

Instead, the load must be split equally to allow for simultaneous charging and draining of the batteries.

The correct way to parallel connect 12V batteries: When connecting 12V batteries in parallel, each wire from each cell must be the same length.

If not, additional resistance is added to the one battery, throwing the circuit out of balance.

This approach has a drawback in that not every RV owner will have enough room for additional exterior terminal posts.

There are different methods to connect your batteries for more balanced batteries if you want to build a large solar power bank with more than 8 batteries, but you must utilize the parallel approach appropriately to maintain your batteries in excellent condition.

Wiring 2 12V batteries to an RV: One of the most common battery configurations, and the one that the majority of RV manufacturers and dealers allow for, is wiring two 12 Volt batteries to an RV.

This approach is valid since it entails connecting several batteries with the load lines from the RV.

This results in an equitable load distribution and a better balanced circuit.

Wiring 3 12V batteries to an RV: This strategy becomes less effective as soon as you start adding more than two 12 Volt batteries to an RV.

However, a third 12V RV battery shouldn’t significantly alter the situation, so you may install it in the same manner as a second.

For the central battery to transfer power uniformly, the load cables must still be attached to the surrounding batteries.

Less amps will be released by the battery in the centre than by the two batteries at the ends, but this difference should be negligible.

You may use the cross-diagonal approach, which I’ll cover in a moment, or the parallel way for three perfectly balanced RV batteries.

RV wiring for 4 12 Volt batteries: When you add 4 batteries to your RV, the wiring becomes a little more challenging.

Although it is still possible to connect the terminals together using the aforementioned techniques, the imbalance is increased.

The first step is to connect two battery pairs using a short cable.

The two sets of batteries are then combined by connecting the two pairs of batteries with a long wire.

Your next step is to attach your load RV power cables to the center terminal using the short and long wires, making sure to connect the negative and positive load wires to two different batteries.

The load cables should be connected to the batteries in the center after everything has been properly wired.

To keep the batteries balanced and the four batteries evenly spaced, each battery should have a long and short wire attached to it.

More than a typical chain of connections with load wires at the ends, adding a few various kinds of connections provides you the best balance.

However, if your battery storage space won’t allow for four batteries to be stacked side by side, you may connect them by utilizing the cross-diagonal approach.

Each battery in the cross-diagonal approach has a long and short connecting wire that are equally balanced.

Related Also: Why Does My RV No Power from Battery?

How to Properly Connect Several 6V Batteries to an RV?

6V batteries can be the best option for you if you want to power your RV with more dependable batteries and want batteries with greater overall amp hours.

There are reasons in favor of and against choosing 6V batteries over 12V batteries, as we have previously mentioned, but ultimately, the ideal batteries for you will rely on personal choice.

The wiring for 6V RV batteries differs somewhat from that for 12V batteries.

An RV cannot operate on with 6 Volts, thus the voltage must be boosted to 12 Volts.

By connecting the positive and negative terminals of two 6 Volt batteries in series, you may raise the voltage.

The voltage rises while the amperage stays the same.

For instance, you would still have 12 Volts but 200 ah if you connected two parallel 12V 100ah deep cycle RV batteries.

But if you connect two 200ah 6V batteries in series, you’ll still get 12 Volts and 200 amp hours.

Fortunately, 6V batteries allow for both series and parallel connections, allowing you to combine 4 or more batteries while maintaining a voltage of 12 and boosting the amp hours.

However, it is never a good idea to mix several amp hour 6 Volt batteries.

You must consistently employ the same kind, size, and, if possible, age.

Wiring 2 6V batteries to an RV: When wiring two 6 Volt batteries to an RV, you must first connect the 6 Volt batteries in series to create a 12 Volt battery.

A short piece of wire, such as the previously described 4 AWG copper wire, may be used to do this.

You still link the load wires to several batteries; never connect both load wires to a single 6V battery.

Wiring 4 6V batteries to an RV: If you’ve already connected two 6 Volt batteries in series to create a 12 Volt battery, wiring two or more 6 Volt batteries in series or parallel to get extra amp hours is straightforward.

To do this, combine each pair of 6 Volt batteries and connect them in parallel like you would two 12 Volt batteries.

Make sure the load (or RV power) cables are connected to various pairs of 6 Volt batteries, however.

In addition to balancing the batteries, this lengthens their lifespan.

How to connect 6 6V batteries to an RV: 6V batteries may be used to build big battery banks, but more than 4 6V batteries will be too hefty, even for an RV.

However, using the same series/parallel approach, you can simply connect six 6V RV batteries together if you need a lot of power for your vehicle.

The batteries must be properly balanced, much as when connecting three 12V batteries.

Although it won’t make much of a difference, you may utilize the cross-diagonal approach to further balance them.

A Battery Cable Is Made Of What Size Wire?

The primary supply line for your RV’s electrical system is made up of cables that connect directly to your batteries.

They often carry greater current (measured in amps) than any other cables or wires in your RV since they are powered directly by the batteries.

Your battery cable size must thus be rated for the greatest current and be the thickest possible.

Depending on how much electricity your RV needs, you must determine what size wire you need for battery wiring.

This question doesn’t have a single right response.

In the sections that follow, we’ll go through how to determine how much power your RV consumes and how to utilize that knowledge to choose the right cable size for your batteries.

Wire Gauge: What Is It?

The diameter or thickness of a wire is measured using a wire gauge.

The American Wire Gauge scale, or simply AWG, is the accepted method of measuring wire sizes in the US.

In the AWG system, the thinner the wire is and the less current it can carry, the higher the cable rating number.

For instance, the chart below shows that 12 AWG, which has a diameter of 2.05 mm, can transmit 20 to 25 amps up to a distance of 4 feet.

Only 15-20 amps can be carried over the same distance by 14 AWG, which has a 1.62 mm diameter.

Determining the Requirements for Wire Size

Longer distances may be covered by heavier cables carrying greater current.

Without going into the math, the explanation for this is that a cable’s resistance rises as its length or diameter decreases.

The amount of electricity you need to transport and the length of your cable runs determine the size of cable you require.

The AWG sizing chart provides the various current capabilities at various lengths as a result.

The needed cable thickness rises in direct proportion to wire length.

Additionally, wires have a maximum voltage rating.

However, you do not need to consider the voltage rating when choosing which battery cable size to utilize since the RV battery cables will only be 12 Volts.

How Much AWG Of Wire Should I Connect My RV Batteries With?

The ideal wire gauge for connecting RV batteries is often 4 AWG, although 6 AWG will also work well.

Where Is The Battery Charger Connected When Multiple Batteries Are Wired Together?

The same battery terminals to which the load wires are attached must always be used for the battery charger.

By ensuring that all of the batteries charge equally, all of the batteries on the same circuit will get the proper amount of charge.

Does My RV Need Two Batteries?

Everything is dependent on the battery voltage.

When utilizing 6 Volt RV batteries, you will want at least two to provide the 12 Volts of electricity required to run the RV.

If you’re using 12 Volt batteries, you just need one, although it’s advised to acquire either one larger 100 ah or two smaller 35-50 ah 12 Volt deep cycle batteries.

Recommended reading: 10 Tips for RV Battery Maintenance

Is It Possible To Combine Batteries With Various Amp Hours?

Once again, it all relies on the batteries you have and the wiring scheme you have in mind.

Batteries with differing Amp hours should not be used when connecting 6V batteries in a series.

However, you may use various battery sizes as long as the voltage is the same if you are wiring in parallel, just like you would with 12 Volt batteries.

I must, however, emphasize how crucial it is to never combine batteries of various ages.

You shouldn’t connect anything together if the age gap is more than six months.

Should an RV Be Plugged In All The Time?

Check to see whether your RV has a smart or 3-stage charger in the converter before deciding whether or not to keep it plugged in all the time.

Older RV models could just have an outdated trickle charger in the converter, which can overcharge your batteries and be just as harmful as having them entirely die.

If your RV does contain an outdated charger, you may just swap it out with a newer one.

It should be safe to leave the batteries plugged in at all times if your RV has a smart or 3-stage charger.

To determine whether the batteries are flooded with lead-acid, you should constantly check on your batteries and monitor their water levels on a regular basis.

Is Series or Parallel Wiring for RV Batteries Better?

Once again, anything will rely on the kind of batteries you are using.

The voltage remains constant but the amperage is raised while wiring 12 Volt batteries in parallel.

However, in order for 6V batteries to have the same power as a 12V battery, they must be linked in pairs and series.

After connecting two 6V batteries in series, you may connect them to another pair of 6V batteries in parallel.

What Distinguishes The Wiring Of RV Batteries In Series From Those In Parallel?

The voltage is raised when batteries are connected in series.

For instance, connecting two 12V batteries in series results in a massive 24v battery, which is a little too much for usage in an RV.

To boost the amp hours rather than the voltage, you should instead link them in parallel.

You can connect two 6V batteries since series wiring raises the voltage.

By doing this, a 12V battery is produced that can now adequately power an RV.

Are RV Batteries Wired In Parallel More Durable?

12V batteries that are connected in parallel surely have a longer lifetime when they are wired properly and with the proper balance.

The battery that is directly linked to the RV, however, might drain and lose power faster than the other batteries if the wiring is done wrong.

Batteries may be more severely harmed by wiring in series, however 6 Volt batteries are favored for their endurance, and there is really little difference between wiring two high-quality 12 Volt RV deep cycle batteries in parallel and two 6 Volt batteries in series.

Related Also: How to Charge Your RV’s Lithium Battery

What Takes Place If the Battery Cable Is Too Small?

The resistance of thicker wires is lower, as we already explained.

As current flows across a wire, resistance in the wire primarily causes two things to occur.

#1. Power Drop

The voltage drops as the initial effect.

This indicates that the voltage at the wire’s end is lower than the battery’s voltage.

Your gadgets won’t function if your voltage drops too much.

Ohm’s law, V=I*R, is used to determine the voltage drop in a wire.

V stands for voltage drop, I for current through the wire, and R for resistance through the wire.

As you can see, your voltage drop will grow if you raise the current, the resistance, or both.

Both the thickness (the gauge) and the overall length of a wire affect its resistance.

An extreme voltage drop that may prohibit your gadgets from operating might happen if your battery wires are too little.

#2. Wires Heat Up

Heat is produced when current flows over a wire, which is the second item that occurs.

More resistance in the wire causes it to create more heat, similar to how voltage drop does.

If wires are too small, they may heat up to the point where the casing melts, and a fire results.

The greatest danger of selecting a battery cable is that is too tiny fires, which may be even more disastrous than an excessive voltage loss.

RV fires often result in the total loss of both the RV and its contents.

The wire that is overrated for the amperage prevents overheating and the possibility of ignition.

When it comes to wire gauge, it’s always preferable to err on the side of caution, but going too large may also be problematic.

What Happens If The Battery Cable Is Too Large In Size?

The cost, weight, and usability of selecting a battery cable wire gauge that is too large are the three main disadvantages.

#1. Cost

Cost is perhaps the most important factor.

Costs for thicker gauge wire are higher.

The increased cost won’t matter if you are just running a short distance of battery wire.

Cost becomes a bigger factor as cable runs lengthen.

#2. Weight and Usability

Weight grows along with wire gauge, same to how price does.

Once again, if your cable lines are short, the extra weight won’t be noticeable.

The last disadvantage of thicker wire is that dealing with it is more difficult.

It’s not enjoyable to try to bend and work with excessively thick wiring in an RV’s tiny, confined compartments.

The disadvantages of picking cables that are too big are far less dangerous than those of choosing cables that are too little.

However, selecting cables that are too thick will just increase your project’s costs, weight, and annoyance.

While going with the thickest cable you can find is not the best course of action, it is safer and better to do so than to go with something too thin.

How Can I Estimate How Many Amps an RV Will Use?

Your current needs may be calculated rather easily.

The majority of the devices and appliances in your RV have a current and power rating.

You can easily calculate your overall current demand by adding the current ratings for all of your devices, provided that they all operate on 12 Volts (the same voltage as your battery system).

You will want an inverter if your gadgets and appliances operate on 120 volts, the same voltage that powers your house.

DC electricity (from the battery) is converted to AC power using an inverter (like in your house).

With an inverter, figuring out your current needs is also a simple process.

To figure out what size inverter you need, you must first add up the total power requirements (measured in watts) of all the appliances in your RV.

For instance, if all of your appliances and devices together use 2,500 watts of electricity, you definitely want a 3,000-watt inverter.

The computation to get the current draw is simple once you know the size of your inverter.

Simply divide the input battery voltage by the inverter’s wattage.

The maximum current draw in our example above is 250 amps when you divide 3,000 watts (the inverter rating) by 12 Volts (the battery voltage).

For Battery Cables, What Gauge Wire Size Should Be Used?

Consider both current and distance when determining the proper wire gauge for your battery cable size.

You merely need to determine how far you need to run your cables now that you understand how to calculate your present demand.

Always keep in mind that shorter is better.

Cable reduction reduces weight and costs.

You can quickly look up the appropriate size battery cable once you are aware of both the cable length and the current.

You can choose the appropriate wire gauge for your RV batteries using the wire sizing chart provided below.

This table makes it clear that smaller cables may be used for lower currents and shorter distances.

Cable Wire Guide: You’ll also see that the necessary cable thickness grows as current or distance do.

If anything gets unclear, see an expert; figuring out the wire gauge is not the answer to your issue.

Conclusion

To really function as a home away from home, an RV requires a lot of electricity, therefore it needs a battery that can keep up.

While a 12V battery may provide a sufficient voltage, two 6V batteries are required to effectively power an RV.

Even if your RV is powered by a 12V battery, it is still advisable to connect additional batteries to the primary one in case your primary battery fails.

Fortunately, connecting several batteries is simple using one of three approaches: parallel wiring, series wiring, or cross-diagonal wiring.

Regardless of the approach, be sure the batteries you’re using are compatible in terms of age, kind, and size, as well as their ability to transmit power evenly.

Related Video from Youtube about RV Battery Wires