Battery cable is used to power electrical system and is sized according to the American Wire Gauge, or AWG for short, specification for electrically conductive cables. Battery cable comes in gauge (AWG) sizes of 6, 4, 2, 1, 1/0, 2/0, 3/0, and 4/0, with 6 gauge being the smallest, and 4/0 gauge being the largest. Battery cable must be sized to the needs of the electrical system, too small of a cable will cause excess heat that could pose a hazard. The size of cable that should be used depends on two things: needed amperage and the length of the cable. Battery Cable Selection Chart can help in determining the size of battery cable need to be used, as well as more information about how to properly size cable and information about voltage drop. Battery cable is SGT type and is available in either red or black. It is rated for use in 12 volt and 24 volt electrical systems with a maximum voltage rating of 60 volts. Cable ends can be terminated using either battery terminals or copper cable lugs.

Battery Cable Amperage Capacity Chart

  Recommended Length and Amperage for Battery Cable while maintaining a 2% or less voltage drop at 12 volts
Battery Cable Size 50 Amps 100 Amps 150 Amps 200 Amps 300 Amps
6 Gauge (AWG)  11.8 ft 5.9 ft 4.4 ft  2.9 ft 2.2 ft
4 Gauge (AWG)  18.8 ft  9.4 ft 6.3 ft  4.7 ft 3.1 ft
2 Gauge (AWG)  29.8 ft  14.9 ft  9.9 ft  7.4 ft  4.9 ft
1 Gauge (AWG)  37.7 ft  18.9 ft  12.6 ft  9.4 ft  6.3 ft
1/0 Gauge (AWG)  47.5 ft  23.8 ft  15.9 ft  11.9 ft  7.9 ft
2/0 Gauge (AWG) 60 ft  30 ft  20 ft  15 ft 10 ft
3/0 Gauge (AWG)  75.6 ft  37.8 ft  25.2 ft  18.9 ft  12.6 ft
4/0 Gauge (AWG)  95.2 ft  47.6 ft  31.7 ft  23.8 ft  15.8 ft.

When choosing the size of a battery cable to power electrical system or project, it is important that it is sized appropriately. As electricity flows through a cable, there is an inherent resistance to the flow of that electricity which will generate heat in your battery cable and manifest itself in the form of what is called a voltage drop. Voltage drop is simply the voltage seen at one end of the cable minus the voltage seen at the other end of the cable. This voltage drop is influenced by the diameter of the copper conductors inside the cable, and the total length of the cable – The longer the battery cable is, the higher the voltage drop will be, and the larger the diameter, or gauge (AWG) of the battery cable, the less the voltage drop will be.

Battery Cable

Car battery cables

Why is voltage drop important? For example, let’s say that length of battery cable is connected to a 12 volt source and has a voltage drop of 2%, which is considered adequate for almost all electrical systems. At the source, or battery, you will read 12 volts using a voltage meter, but at the other end of the cable voltmeter will only read 11.76 volts (12 volts -2%). If circuit needs 100 amps of current, the battery cable will absorb 24 watts of power because of it’s resistance. Now lets say that your voltage drop is 10%. Now your voltmeter at the other end of your battery cable will read 10.8 volts (12 volts – 10%) and that same 100 amp current draw will cause battery cable to absorb 120 watts of power.Cable will definitely get warm to the touch. This amount of voltage drop will cause other devices to not work properly – light bulbs will be dimmer, fans and motors will be weaker, and if the voltage drop is high enough computer systems can fail, and even the cable itself can be destroyed leading to a catastrophic failure and even an electrical fire.

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