Which Size of Battery Cable Is Best for Me?

Which Size of Battery Cable Is Best for Me?

Upgrading their battery systems is one common improvement made by boaters and RVers. Selecting the appropriate battery cable size for your system is crucial, regardless of whether you’re building a new solar power setup or adding an extra battery. Let’s get started by discussing the significance of choosing the appropriate cable size and, more importantly, how to accomplish it!

What Is The Battery Cable's Wire Size?

An RV’s electrical system is mostly powered by cables that are directly connected to its batteries. Your battery cable size must therefore be rated for the maximum current and, in the end, the thickest.

The amount of power your RV needs will determine what size wire you need for your battery wiring. This question doesn’t have a single right response.

We’ll go over how to calculate your RV’s power consumption below, and how to utilize that data to choose the right cable size for your batteries.

Wire gauge: what is it?

The American Wire Gauge scale, or AWG for short, is the accepted US standard for measuring wire gauges.

According to the AWG system, a wire’s thickness and hence its maximum current carrying capacity decrease with increasing cable rating.

With a 1.62 mm diameter, 14 AWG can only transport 15-20 amps over the same distance.

Requirements for Wire Size: Factor Identification

Longer current transmission distances are possible with thicker cables. This is because, without getting into the math, a cable’s resistance rises with decreasing diameter or increasing length.

As a result, the amount of current you need to carry and the length of time your cable runs need to be relies on what size cable you require. The necessary cable thickness rises with the cable’s length.

Additionally, wires have a maximum voltage rating. When choosing the size of battery cable for your RV, you don’t have to worry about the voltage rating because the cables will only be 12 volts.

Cables for batteries

If the battery cable is too small, what happens?

Thicker wires have less resistance, as we have already discussed. There are two basic effects of resistance on current flowing through a wire.

Drop in Voltage

A wire’s resistance depends on its overall length as well as its thickness, or gauge. One problem that might arise from undersizing your battery cables is an extreme voltage drop, which could stop your electronics from functioning.

Wires Heat Up

Heat generation is the second thing that occurs when current flows through a wire. More resistance in the wire causes more heat to be produced, just as voltage loss. Undersized wires have the potential to heat to the point where their housing melts and starts a fire. The greatest risk associated with selecting a battery cable that is too small is fire, which can be even more disastrous than excessive voltage drop.

What Takes Place If the Battery Cable Is Too Large?

Selecting an excessively large battery cable wire gauge has three main disadvantages: expense, weight, and convenience of usage.


Cost is arguably the most important factor to take into account. Gauges with thicker wire cost more. The additional expense will not be noticeable if the battery wire you are using is only a few feet long.

Weight and Usability

The weight increases with the wire gauge, much like the expense does. Once more, the additional weight won’t matter if your cable runs are short.

Working with thicker cables is more difficult, which is the last disadvantage. It’s not enjoyable to try to bend and work with excessively thick wiring in the tiny, confined spaces of an RV.

The disadvantages of picking too-small battery cables are far greater than those of choosing over-sized ones. On the other hand, selecting overly thick wires can make your project heavier, more expensive, and more frustrating. Choosing the thickest cable you can find isn’t a sensible idea either, even if it’s safer and wiser to go too big than too thin.

How Can You Estimate How Many Amps an RV Will Need?

Finding out what you currently need is not that difficult to do. In your RV, the majority of devices and appliances will have a power and current rating. Assuming that your battery system and all of your gadgets operate at 12 volts, you may calculate your total current draw by adding the current ratings of each device.

Power bank setup for Maxworld Power batteries

You will require an inverter if your gadgets and appliances operate on 120 volts, which is the same voltage as the power in your house. For example, you should get a 3,000-watt inverter if the total power consumption of all your electronics and appliances is 2,500 watts.

Just divide the input battery voltage by the inverter’s watt rating. The maximum current draw in the aforementioned example is 250 amps, which is obtained by dividing the inverter rating of 3,000 watts by the battery voltage of 12 volts.

What size gauge wire is appropriate for battery cables?

Recall that shorter is usually preferable. Less cable equals less money and less weight.Knowing the current and cable length will allow you to rapidly determine the appropriate battery cable size. It is evident from this table that smaller cables are possible due to lower current and shorter distance.

Guide to Wire Cables

You’ll also see that the necessary cable thickness grows with current or distance. If something starts to get difficult, get help from an expert; figuring out which wire gauge to use won’t solve the issue.

Selecting the Appropriate Size of Battery Cable

RV battery cables are a tiny but crucial component of a large and intricate system in your vehicle. Selecting the incorrect size battery cable might result in additional expenses, annoyance, and sometimes even a fire.


Choosing the appropriate battery cable size for your system doesn’t have to be difficult, though. Make sure your RV battery upgrade job is a success by using the above advice or by contacting a Maxworldpower with any queries!

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