The size of your jumper cables will affect the amount of amperage that can pass through them to start a dead battery. It is, therefore, important to predetermine the size of the jumper cables you need before purchasing a pair.
The size or gauge of a jumper cable refers to the width of its wiring. Jumper cables with small gauge ratings are thicker in diameter and allow more current/amperage to pass through. Thin jumper cables, on the other hand, allow less amperage to pass through and take longer to charge a dead battery.
Additionally, thin wires heat up faster since they are carrying more power than they can handle and will often feel warm to the touch. This article provides a comprehensive guide on buying the best jumper cables.
Purpose of jumper cables
Jumper cables are insulated wires equipped with enough capacity and alligator clips at both ends used to interconnect the disabled vehicle with another vehicle complete with the same system voltage. They are, therefore, used to recharge a dead battery.
During the jump start procedure, both batteries are required to generate an equal voltage, meaning that the voltage between the two negative or positive terminals should remain at 0, thus no electrical flow.
Jumper Cables Size Chart
| Gauge Size | Diameter in mm | Length in feet |
| 10 | 2.58826 | 5 |
| 8 | 3.2639 | 10 |
| 6 | 4.118 | 15 |
| 4 | 5.18922 | 20 |
| 2 | 6.54304 | 25 |
| 1 | 7.34822 | 30 |
A 10 or 8 gauge jumper cable is sufficient for compact and subcompact cars due to their battery size. The six gauge falls under the ‘standard gauge’ category and will work on most vehicles. Heavy-duty trucks and diesel engines will need 4-1 gauge jumper cables due to their high compression ratios. Unlike mid-sized cars and non-diesel engines, heavy-duty trucks and diesel engines need as much as 1,500 Amps for a successful jumpstart.
Lower gauge numbers cables are more expensive and come with better perks such as surge protection. Additionally, jumper cables with small gauge numbers offer longer cable lengths (up to 25 feet long) providing you with adequate battery to battery reach for any situation. Also, jumper cables, in general, take up minimal space; as a result storage of longer and larger jumper cables is a non-issue.
What level of amp jumper cables do I need?
Jumper cables come in different amp settings and can range anywhere from 300-3,000 amps. However, the amps/current needed to restart a dead battery depends on the size of the engine. Small to midsized cars as well as small trucks and SUVs will need to draw between 300-600 amps from a working battery for a successful jumpstart.
Your vehicle may, however, need more amps if the battery is completely dead or if it’s cold. Colder temperatures adjust the electrical charge in a battery, increasing the amount of current needed to restart an engine.
Car batteries are therefore rated in Cold Cranking Amps (CCA). This number will be higher than the actual amps needed to restart your engine to make up for the instances when your battery has been completely dead for a while and or freezing temperatures.
Your engines CCA should guide the amp range you select for your jumper cable. Also, it is recommended for you to wait a bit after connecting your jumper cables to a working battery before starting the ‘dead’ car. This will allow the dead battery to charge up.
Heavy-duty trucks usually have diesel engines that need a significantly higher amperage than petrol engines — also, the more cylinders, the more current needed. You should always look at the size of your engine, whether it is diesel/petrol or gas and the number of cylinders when deciding what level amp jumper cables you need.
Lower gauge jumper cables allow more current to flow through them. Truck drivers should be at ease with a jumper cable that has a peak of 1,500-3,000 Amps. Also, the car will regulate and draw the amps it needs to restart, so you don’t have to worry about using a 1,000 Amp jumper cable on an engine that only needs 400 amps.
Other considerations you need to make before purchasing a jumper cable include:
- Insulation
A heavy insulated wire will allow more electric current to pass through and generate less heat in the process. Trying to visibly identify a heavily insulated cable is near impossible, especially when all the jumper cables are labeled ‘heavy duty.’ You should always check the gauge number lest you end up with a thin wire wrapped in thick insulation. The smaller the gauge rating, the thicker the insulation and wiring.
- Length
Longer cables are better since they’ll have further reach. This comes in handy in situations where the vehicle with the working battery cannot pull up next to the ‘dead’ vehicle and has to remain parked behind the ‘dead’ vehicle. Purchasing a 20 or 25 feet jumper cable guarantees you easy battery to battery access for any possible scenario and comes highly recommended by DIY enthusiasts.
- Clamps
Jumper cables with gauge numbers that range from 4-1 have larger clamps with twice the grip space keeping your fingers a safe distance away from any sparks. Cheap clamps will not be made of solid copper and have poorly insulated handles. They get worn out much quicker and transmit electricity less effectively. Heavy-duty clamps, on the other hand, are made of solid copper which allows them to last longer and transmit power much faster. They come fitted with ergonomic handles that are thickly insulated for shock protection and better conductivity.
- Price
Jumper cables with lower gauge ratings are more expensive. Though an eight gauge will probably work on your vehicle, it will have poor insulation and cheap clamps. Poor insulation will cause your jumper cables to heat up while cheap clamps will have poor conductivity, and this will either prolong or disrupt the jumpstart process. Purchasing expensive jumper cables is an investment, so get the best and longest you can afford to buy.
Charging the car battery
The first thing that you should establish before recharging a dead car battery is how dead it is, you should, therefore, get hold of a voltmeter and measure the volts, a healthy battery should have at least 12.4 to 12.7 volts across both terminals. But if you get a reading that is lower than the above then you will encounter starting problems.
So the above results will then decide which method will best recharge the battery after jumpstarting and getting it back on the road.
Driving
Did you know that your battery gets charged when you drive around, but here you will have to switch off everything that will burden the battery such as the lights, the heating and cooling devices, and the stereo system? The car battery is normally charged by the alternator, and even more interesting is that if you can keep your engine RPM up then the alternator will charge the battery at a faster rate.
Also, keep the car as idle as possible because higher revolutions have been known to add more power to the charging circuit.
Invest in a dedicated charger
A dedicated charger can be used either before or after charging as it will charge your battery at the convenient rate that will neither damage it but deeply charge it. Remember that it’s not the function of your alternator to charge your battery especially if it has below 12 volts, as it risks getting damaged. It can, however, maintain your battery with the right charge if the battery is without issues.
Frequently Asked Questions
Is it safe to jumpstart another car?
Jumpstarting another car is a very risky affair because you risk damaging either one or both of the cars. The major problem in this scenario is the possibility of an overvoltage that will most likely damage the headlights if they are on and other electronic equipment that will be on during the procedure.
When jumpstarting another car, how long should it take?
If the car being given a boost won't start then you will have to let the savior car run for at least 10 minutes while hooked up to the dead battery. you can also rev the engine slightly, which may encourage a change in the dead battery and enable it to restart. Be mindful however that if you give it up to four trials and it still doesn’t pick up then its best to find other alternatives.
Does idling a car in any way drain the battery?
If your battery is faulty and cannot hold a charge for long then idling will drain the battery, also, if you have high-energy consuming electricals in your car, idling will definitely drain or kill your battery. However, if your battery is not struggling with any of the above issues then idling will not have any effect on your battery.
Does driving short distances affect the car battery?
There isn't a better way to kill your car battery than driving short distances and the simple reason is that short trips don’t give your battery time to fully recover, as your battery alternator rarely gets time to recharge the battery after it has been started.
Conclusion
Some may say that the size of a jumper cable doesn’t matter as much as the engine size since your engine will only draw the amount of current it needs to restart. But this cannot be further from the truth. Jumper cables with higher gauge ratings (10-8) have thinner wires.
Thin wires can only carry a small amount of electrical current at a time, and this increases the time needed for your engine to draw enough power for a restart. Also, they will not be able to jumpstart a semi-truck or diesel engine. Size, therefore, matters when it comes to jumper cables.
