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How to Jump Start a Diesel Truck With 2 Batteries

When you jump into your diesel truck, you expect it to start the moment you turn the ignition. But when you hear a simple “click-click-click” noise and nothing happens, your heart sinks as you realize you’re not going anywhere any time soon. 

This clicking noise means one thing. You have a dead battery. You can fix a dead battery with a simple jumpstart. 

But what happens when you have two batteries in your vehicle? How do you know if one battery is going bad? And exactly how do you jump-start a truck that has more than one battery? 

By the time you finish reading this article, you will know how to jump start a diesel truck with 2 batteries as well as how to maintain your truck batteries. 

Do Trucks Have Two Batteries?

Not all diesel trucks have two batteries. With that said, many do. The dual-battery setup allows the engine to have extra power and thus overcome resistance more easily. 

Gas engines do not need the same amount of power to start as diesel engines. This is why you typically only see one battery in a gas-powered vehicle but see two in a diesel-powered vehicle. 

How to Jump Start a Diesel Truck With 2 Batteries

Charging a dual battery truck does not look much different than charging a vehicle with one battery. You only need a willing individual to give you a jump start with their perfectly good battery. You also need some jumper cables. 

Here’s how you jump start a diesel truck with two batteries. 

  1. Make sure both vehicles are in either park if you have an automatic transmission or neutral if you have a manual transmission. 
  2. Turn off anything that would take up battery power such as lights and radio. 
  3. Connect the red jumper cable clamp to your dead battery’s positive terminal, the one that has a red cover or a plus symbol on it. 
  4. Connect the other red clamp to the good battery’s positive terminal
  5. Connect a black clamp to the negative terminal on the good battery. 
  6. Connect the other black clamp to some unpainted metal on your vehicle or the vehicle with the dead battery. 
  7. Start the vehicle that has a good battery, and just wait a few minutes for your dead battery to charge. 
  8. After a few minutes, crank the engine on your diesel truck. 
  9. If this doesn’t work, wait a few minutes longer for the battery to charge. 
  10. Remove the black cables first, one at a time. 
  11. Remove the red cables one at a time, being careful to not allow the cable ends to touch while they’re still connected to the battery. 

Do not turn your truck off immediately. Instead, let it run. This allows the alternator to recharge your batteries. 

If you can, take the truck for a drive, and let it run for at least 20 minutes. Then stow your jumper cables in a handy spot so you can help someone else out when they need it. 

Signs of a Dying Battery

The novice driver cannot tell immediately that their battery is dying. They just know that their car is doing bizarre things. Here are a few of the common signs that your battery is beginning to die. 

  • Sluggish engine
  • Dim headlights
  • Clicking sound when you try to start the battery
  • Basic functions like radio and globe light stop working

Your battery controls many parts of your vehicle. Thus, when your diesel truck starts to act bizarre, take it in to see if you need a new battery before you find yourself on the side of the road with a dead battery.

Safety Tips When Jumpstarting a Battery

Any time you work under the hood of a car, you’re putting yourself at risk. You’re working with fast-moving parts and a fuel-operated engine. Follow these basic safety tips when you’re jumpstarting your battery to protect yourself from danger. 

Before you jumpstart your battery, turn on the heater. This keeps your electric system from frying if a voltage surge takes place when you jumpstart the vehicle. 

Clean off the connections and battery terminals before you hook up the battery cables. A wire brush does the job well. 

Always read the owner’s manual first. This will tell you if you have jump-start plugs instead of access to your battery. 

Make sure your cables cannot easily touch each other.

Turn on the heater for the vehicle with the dead battery. This will protect the electric system in case of a surge in voltage during jumpstarting. Also, verify the voltage in the batteries before you begin. 

Make sure your vehicles are in park, and then put on protective gear. Ideally, you should wear protective eyewear and rubber gloves. 

Avoid These Things

Do not light up a cigarette or any other apparatus while you’re working on your jumper cables. A single spark will cause all kinds of problems. 

Also, check the battery before you begin. If it has a crack or leaking fluid, leave it alone. Do not jump start this battery. 

In extremely cold weather, move with caution. You should not attempt to jump-start a battery with temperatures below freezing. 

Protect your face and head by not placing it over the battery in the process. 

When you rev your engine, accelerate steadily. Do not gun the engine by pressing on the accelerator quickly. 

Never ever let the jumper cable ends touch each other.

Jump Start and Move On

Now that you know how to jump start a diesel truck with 2 batteries, you can drive your truck with confidence. Keep an eye out for the telltale signs that your battery is beginning to fail. When the lights dim and the radio doesn’t work, you usually have a battery problem. 

Remember also that an electrical problem such as this could mean bigger issues such as a problem with your alternator. Begin with the battery, and then move on to the more complicated possibilities. 

Do you need a good diesel truck mechanic? If so, contact us. Our experts are ready to help you with all of your diesel truck problems from helping you maintain it to fixing the biggest of issues. 

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