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HomeTips & GuidesBattery cable 6 gauge: Is it enough for a battery-to-starter connection?

Battery cable 6 gauge: Is it enough for a battery-to-starter connection?

About Battery cable 6 gauge, An automotive wiring harness has many electrical connections; however, one of the most important is the battery-to-starter wiring. Whether replacing old wiring or upgrading your starter to power-upgraded components, you need battery cables with the correct gauge.

Vehicles use different gauge cables for battery connection (6-gauge, 4-gauge, 2-gauge). In this article, we will read about whether battery cable 6-gauge is good for battery-to-starter connections.

Table of Contents

What is the battery cable 6-gauge?

Battery cables 6-gauge have flexible stranding, which has a longer lifespan than other types of battery cables in the market.

Generally, battery cables use a 4-gauge cable for the battery’s positive terminal to the starter connection and a 2-gauge wire for the negative terminal.

However, which gauge wire you must pick always depends on the current drawn by the starter motor and the distance between the battery and the starter.

Factors determining battery cable 6-gauge:

Two factors help determine the correct gauge wire for the battery to starter connection.

Ampacity or current carrying load:

A vehicle starts mainly because of the starter and the battery. The battery supplies power to the starter, which cranks and starts the engine. If the engine is large, it will need more amperes to start the vehicle.

The table below gives you an idea about the ampacity or current drawn by the starters of different engines. You can also check the label for more precise information.

Vehicle/engine TypeStarter draw (Ampacity)
Big trucks and other powerful engines125-150 amperes
V6 or six-cylinder engine175 amperes
V8 or eight-cylinder engine225 amperes
Sports Utility Vehicle200-300 amperes
Huge trucks and very powerful enginesUp to 1500 amperes and more

Further, the current drawn also depends on whether the engine is cranking or spinning freely. The same starter may draw around 80-90 amperes current when you are testing it on your workbench but will draw around 250-300 amperes while starting an engine.

Besides, the battery condition, ambient temperature and viscosity of engine oil, and the corrosion around terminals also determine the drawn current.

The cable length between the starter and the battery:

The cable length is the distance between the battery and the starter. As the distance increases, you may face a higher voltage drop, thus requiring thicker wire.

The table below shows the battery cable gauge at 12 volts for a certain length and amperage while maintaining a voltage drop of 2% or less.

Which gauge wire you must use?Length of wire in feet (starting from battery to starter)
0-44-77-1010-1313-1616-1919-22










Ampacity of the starter
0-2012121212101010
20-35121010101088
35-501010108886 or 4
5-651010886 or 46 or 44
65-8510886 or 4444
85-105886 or 44444
105-125886 or 44442
125-15086 or 444222
150-2006 or 444221/01/0
200-25044221/01/01/0
250-3004221/01/01/02/0

Here is another table that shows the battery cable gauge at 24 volts for a certain length and amperes while maintaining a voltage drop of 2 % or less.



Which gauge wire you must use?
Length of wire in feet (starting from battery to starter)
Less than 5 feet5-10 feet10-15 feet15-20 feet20-25 feet25-30 feet
Ampacity of the starter0-3014 1410886
30-5012 108664
50-7510 86442
75-10064421
100-125444221
125-150221100

From the tables above, you can easily find when the battery cable 6 gauge is suitable.

Jumper cables

Jumper cables

What if you pick a thinner one than the battery cable 6 gauge?

Thin wires lead to two phenomena in the cable while the current passes.

Voltage drop:

The formula for calculating voltage drop in a wire is V= I*R.

Where R refers to the resistance, I refers to the current, and V refers to the voltage drop.

With this formula, it is clear that as the current and the resistance increase, the voltage drop in the wire also increases.

Resistance is inversely related to the wire thickness and the cable length. If you take too thin cables, high resistance will lead to excessive voltage drop. As a result, your electronics may not function as intended.

Most manufacturers specify a bearable total voltage drop on positive and negative terminals around 0.5 volts for a 12-volt engine and 1.0 volts for a 24-volt engine. If the voltage drops below this threshold, it may be a concern.

Apart from length and thickness, the corrosion around terminals, incorrectly crimped connectors, and loose connections can also affect the voltage drop.

Hot wires:

Higher resistance in the wires will also lead to heat generation. Thus, too thin cables may lead to increased heat generation, further melting wires. Sometimes, they can also lead to fire accidents. 

What if you choose a thicker one than the battery cable 6 gauge?

You may face three drawbacks of using a thicker battery cable:

Cost:

Thicker wire will cost more than their thinner counterparts. You may not feel the cost difference for a few feet of cables, but if the cable length increases, the cost difference is significant.

Weight:

As the wire becomes thicker, it increases its weight also. The added weight may be insignificant for short cables, like the cost difference.

Ease of use:

Installing thicker wires becomes daunting as you may face difficulty bending the wires in cramped spaces.

Exact Battery Cable Gauge Calculation:

Besides referring to the table above for determining the right wire gauge, you can also do the same by determining the cross-sectional area with this formula:

A (cross-sectional area) = I (current) * conductor resistivity * { L (length)/ D (max allowable voltage drop)}

  • The cross-sectional area (A) is determined in square meters.
  • The current (I) is the maximum current that flows in the wire in amperes. The amount of current depends on the oil viscosity, motor condition, temperature, and engine size. In a typical four-cylinder engine, this current draw comes around 125-150 amperes. For other engines, please refer to the table mentioned above.
  • A standard polyvinyl-coated copper cable has a conductor resistivity of around 1.7* 10-8 ohms.
  • The length (L) is the wire length in meters measured from the battery to the starter.
  • D or maximum allowable voltage drop for a 12-volt battery is 0.5 volts.

The above formula helps you calculate the cross-section area in square meters. You can convert this into square millimeters with this formula.

Area (in meter square) * 1,000,000 = Area (in millimeter square).

Once you convert this, use the table below to find the corresponding value in the AWG system.

Gauge numberInchesMillimeters
2/00.3647979.266
1/00.3248618.251
10.2892977.348
20.2576266.544
30.2294235.827
40.2043075.189
50.1819414.621
60.1620234.115
70.1442853.665
80.1284903.264
90.1144242.906
100.1018972.588
110.0907422.305
120.0808082.053

Conclusion:

So, using oversized or undersized wires is not a good strategy if you want a durable and functional system. 

Although an oversized one won’t give you a multifunction problem, always pick the correct size cable with the right cable connectors.

If you have questions regarding the battery cable assemblies, disconnect switches or battery boots, contact Cloom

Our professional team is ready to address all the related issues and will help you get the best battery cables.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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