Best Jumper Cable Sizes

Here’s a little advice for the best size jumper cable size to keep in your car or truck.

You do have jumper cables in your vehicle, right?

Did you know that cold temperatures will greatly reduce your car’s battery capacity? And that’s one reason why it’s a good idea to keep jumper cables for just in case. Another is being a good Samaritan.

As a car battery ages, it will become even more susceptible to poor starting during cold weather. In fact, a car battery can freeze solid in cold weather if it becomes too weak!

If a car battery has a full charge, it will not freeze unless temperatures get to 76 below zero. Unless you’re living on Mars, your car should start in cold weather if the battery is in good condition and fully charged.

On the other hand if a battery is fully discharged (dead as a door nail), it will freeze solid at 32 degrees F! As you can see, a partially charged weakened battery will be susceptible at cold temperatures.


Best Jumper Cable Size (Gauge)

The thing with wire size is this:

Size matters.

– The smaller the wire diameter the less power it can handle.
– The larger the wire diameter the more power it can handle.

When starting a car engine it is amazing how much power gets sucked from the battery. In other words, a typical car starter requires a lot of DC Current (Amps) to start the engine.

How much current flow? How many Amps to start a car?
It varies depending on the engine. Generally, a typical car requires about 300 – 500 Amps from the battery while starting.

Diesel engines require more because they have a very high compression ratio. A diesel truck engine may require as much as 1,000 Amps during start up.

Note: The colder it is, more Amps are pulled from the battery. Cold temperatures reduce the electrical charge voltage in a battery and increases the amount of current (Amps) needed to start a vehicle.

Note: Car batteries are rated with Cold Cranking Amps (CCA). It is a rating for the amount of Amps a battery can discharge in 30 seconds at 0 degrees Fahrenheit while maintaining full charge voltage. The higher the CCA the ‘beefier’ the battery.


Wire Gauge For Jumper Cables

Now that we know how many Amps may flow through jumper cables, we can consider the wire gauge size.

It’s all about gauge. Jumper cable gauge refers to the thickness of the cable’s wiring.

Note: When looking at wire gauge numbers, the higher the gauge (numerically) the thinner the wire. The lower the gauge number the thicker the wire.

The best jumper cables will be those which are able to flow the most energy from one battery to another. Thicker jumper cables (lower gauge) can transfer more power than thin jumper cables.

For Most Cars

For most cars I recommend 4 gauge jumper cables.

The following set will crank 500 Amps and is 20 feet long:

4 Gauge x 20 Ft 500A Heavy Duty

For Trucks

For heavy duty trucks, especially diesel I recommend 1 gauge jumper cables.

This set of cables will crank 800 Amps and is 25 feet long:

1 Gauge x 25 Ft 800A Heavy Duty

I posted this because yesterday I had to jump a vehicle, and I was glad that I had heavy duty jumper cables in my truck!

Tip: There’s also something called a Jump Pack which has a built in battery designed to jump start a vehicle:

Jump-N-Carry JNC660 1700 Peak Amp 12V Jump Starter

More: Battery Voltage State of Charge Chart

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