Battery Cable Size Chart

Updated: July 21, 2023

Charts and graphs are a good way to visualize the effects of a particular component. 

Finding the correct battery cable size isn’t as easy as some make it out to be. 

You need to understand the effects of changing the size as well as what happens once you purchase a bigger cable.

Let’s have a look at a battery cable size chart and see how the values compare.

What Are the Effects of Changing the Battery Cable Size?

If you got yourself a brand new deep-cycle solar battery, chances are that it came with a set of cables. But what’s the science behind them?

When electricity is conducted through a cable, you’re bound to lose energy and have a voltage drop.

You will also always encounter resistance in the wire as you conduct electricity. 

This is due to the inverse linear proportional relationship between the cross-section area of the cable and the resistance you encounter. 

In less technical terms, as your cable size goes up, your resistance goes down. 

However, as your resistance decreases, so too does your voltage drop at the end of the wire. 

As the voltage drop decreases, the available voltage running through the appliance goes up, and as this goes up, the power goes up at your appliance.

When you have a larger wire size and a lower resistance, you lose less electricity. 

Understanding this relationship will make using any solar cable size calculator a breeze as you will have an idea of how wires work as well as the effects of changing them.

Choosing the Correct Size

When consumers are deciding on which battery cable size works best, they typically only answer one question. 

What is the maximum amperage that I can feed through my wire? 

As much as you can answer this question by looking at a battery cable ampacity chart, there are other factors to consider besides answering a single question.

With whatever size you choose, you want the end goal to be an acceptable voltage drop at the end of your cable. 

Voltage drop is a result of the amperage flowing through the cable and the total resistance of the cable itself.

If you can’t reduce the length of the cable then check for excessive ambient temperatures. Let’s say your cable is exposed to light or heat.

The temperature of the wire rises, increasing the resistance. 

So the best way to choose the correct size cable for your battery is to calculate the voltage drop.

Voltage Drop

There are plenty of calculators online that allow you to calculate voltage drops using values obtained from wire speed and voltage charts. 

When you’re calculating the voltage drop, your goal or aim should be below 3%. This is typically achieved by changing the wire size variable in the calculator. 

Voltage drop can also be manually calculated. You take the current measured in amps and multiply it by the cable length in meters. 

This value is then divided by the system’s single or three-phase amperage.

A calculator will give you a more accurate value so rather let the computer do all the work.

Reducing Energy Losses

Energy Loss is determined by 3 things. The first is the length of the wire, the second is the size of the cable itself, and the final is the amperage running through the cable.

The first and second variables are relatively easy to alter as it’s simply a matter of changing the cable.

Reducing the amount of amperage can be difficult because the load connected to your battery has a specified power input required to function. 

However, it’s not impossible. The easiest way to decrease the amperage is to double the voltage. In other words, if you’re multiplying the voltage by 4, you would divide the amperage by 4.

To do this, you increase the voltage on your power generation system, in this case, the solar panels. You can also increase the voltage on your battery bank to see results.

Battery Cable Size Chart - Explaination and Chart

The most common method of determining the battery cable size is using the American Wire Gauge.

It can be confusing at first as the smallest wire size has the biggest number. This number is 40. 

If you want to go one size up from the smallest number, it goes to 39. It continues to decrease up until the number 1. 

This concludes with the smaller cable size.

The medium and large sizes start at the number 0. If you go up one size from 0, it goes to double zero, then triple zero, ending at quadruple zero.

Every time you increment the wire size by 1, the diameter of the cable increases by 1.123.

The other standard for determining the battery cable size is using the International Electrotechnical Commission. 

This is a straightforward approach as it divides the classes of cable sizes based on the cross-sectional area of the cable. The unit used is squared millimeters.

Using a wire gauge voltage chart makes it easier to find the size you’re looking for. Wire gauges are used to measure a cable or wire’s diameter or thickness.

Battery Cable Size Chart

Conclusion

There are plenty of charts associated with all things batteries and solar. 

You can use a high or low-voltage wire gauge chart to see the amount of current flowing through or the size of your cable. 

The battery cable size chart is a good way to see the effects of changing a cable size as well as deciding whether you need an upgrade.

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