Hooked Battery Up Backwards Now Car Won’t Start: How To Fix?

Hooked battery up backwards now car won’t start? Many people make this mistake when replacing or repairing the battery by themselves because of carelessness or lack of skill.

In a worse case, this error can lead to many other problems, even making the damage more serious, and you may have to pay more for the third-party service.

What happens if you put battery in backwards? How can you fix it? Our next parts show you the answers!

What Damage Can Connecting Backwards Cause?

Hooked Battery Up Backwards Now Car Won't Start

What happens if you hook a battery up backwards? Here are some common problems that you will probably face at least one or even all of them

  • The charger’s electronic components could be damaged by the current going to the battery.
  • Its circuit could be ruined in part or entirely.
  • If the charger’s rating is lower than the battery capacity, it would overload the circuit and may trip the circuit breaker, stopping the operation of the circuit.
  • The battery may overheat and burn with ejection once the charger’s rating exceeds its capacity.
  • It could be irreparably harmed or spark discharged.
  • The damaged cover might allow acid to enter, melting delicate equipment and potentially inflicting serious issues.

Can The Battery Explode If I Connect It Backward?

Could connecting the battery backwards lead to more serious problems, like fires and explosions?

Remember when you wrongly connected the power cord of the battery? Usually, it will have a flash of electricity, which looks quite scary. And then, suddenly, the current in your car stops.

However, if the problem is only that you cannot continue to start the car, it is still considered lucky because the possibility of fire and explosion can still occur.

A fuse intended to safeguard the electronics of the car should blow in the case of the car battery connected backwards.

You will transmit electrical current backward through the ECU, ECM, and more if your automobile doesn’t have a fuse (nearly all cars do) built for this purpose.

Hooked Battery Up Backwards Now Car Won’t Start: How To Fix?

How to fix it if I hooked my battery up backwards? You need to have different solutions depending on the situation and the problem you face after doing this.

Usually, the driver will repair the system and electrical components or replace the battery with a new one.

Dead Battery

Your battery can be destroyed if you start your automobile after installing it incorrectly. Most of the time, a dead car battery will be obvious since the contents will leak out and make a mess.

It’s time to change the battery if your automobile won’t start due to a dead one.

Blown Fusible Link

Fusible links are used in many older vehicles for damage prevention. It is a thin wire with thick insulation intended to break when the system experiences an excessive current flow.

The thin wires, known as fusible links, are positioned between layers with a lot of electricity.

However, if it exceeds the limit, it will cut off the power, and the automobile will be kept from catching fire thanks to the thick insulation.

In this case, replace the blown fusible link, following these steps:

  • The negative terminal should be disconnected.
  • Cut the fusible connections on both sides with a pair of pliers.
  • Start attaching the new fusible connections to the interior of the wires and the neighboring wires.
  • Make sure the wires are tightly twisted for a solid connection.
  • To ensure that the connection remains in place, add a crimp.
  • To strengthen the connection, heat the connecting wire using a soldering iron.
  • The overhanging wire should be covered with a heat shrink tube.
  • Use a heat gun to set the heat shrink tube.

Fried Alternator

If the issue is resolved by changing blown fuses or repairing fusible connections, you’re fortunate because no crucial engine part has been harmed.

However, if the generated current is excessive, the battery put in backwards might still fry the alternator even after the fuse has been blown. That will prevent your automobile from starting.

It is quite complex and involves major components of the engine. Therefore, please seek help from experienced technicians to avoid more serious consequences.

Damaged ECU

A damaged ECU is the worst-case result of having the improper car battery terminals connected. Even though it is uncommon, the ECU might nevertheless be damaged by a current flow that is too big.

Repairing the harm caused by the electric current may work if it isn’t too severe. Otherwise, you’ll need to replace it.

Depending on your car, replacing the ECU can cost anywhere from $800-$1500. You should have certified mechanics examine it and let you know if it can be fixed.

Blown Fuse

If you connected the positive and negative battery terminals in the wrong way to safeguard other components from serious damage, a blown fuse happens and causes the car to not start.

Most fuses attached to the battery are 80 or 100 amps. When it dies, the fuse that connects to it is readily blown.

Your automobile won’t start if there is a blown fuse, regardless of your attempts to jump start it with jumper wires.

A new fuse must be used to replace a blown one, given that it has the same amperage.

To change a car’s fuse, adhere to the following instructions:

  • Take out the old fuse by removing the two screws holding it in place.
  • By stacking one fuse on top of the other, you may compare the two fuses’ sizes.
  • Use a tungsten pen to mark where the new fuse needs to be cut.
  • Cut them with scissors to make the new fuse’s edges equal those of the old one.
  • In the new fuse, drill the hole.
  • Check the two fuses once more to see whether they are compatible.
  • In the fuse box, place the new fuse.
  • Tighten the two screws.

How To Hook Up Battery Jumper Properly?

You’ve known what happens if you hook up a car battery backwards; because of the consequences it can bring, the best way is to learn how to do it properly.

The situation of crossed battery cables car won’t start is something that no one wants!

Step 1: Stabilize Your Vehicle

Step 1: Stabilize Your Vehicle
  • To apply the brake, put the automobile in the park.
  • Remove the key from the vehicle with the dead battery to prevent the jumper wires from starting the vehicle.

Step 2: Check The Battery’s Situation

Step 2: Check The Battery's Situation
  • Make sure the batteries have the same voltage.
  • Find each vehicle battery’s negative and positive battery terminals.
  • Look for corrosion on the terminals. Wipe the terminals with a rag or wire brush to clean them.

Step 3: Attach The Cables

Step 3: Attach The Cables
  • Place the cable clamps flat and separately on the ground. Keeping them in contact will create a hazardous short circuit.
  • Attach a red clamp to the dead battery’s positive terminal and the black to the negative one.
  • Avoid blunders that could harm the vehicles by connecting them one by one carefully.
  • Put the other red clamp on the positive terminal of the good battery (donor one).
  • Make sure it is fastened securely so it won’t come loose when the engine is later started.
  • If a clamp is not properly fastened, stop before starting the automobile.
  • The other black lead doesn’t connect to any terminal, but you have to clamp it on a bare metal surface, such as a clean bolt in the engine block.
  • The clamp can also be positioned on any metal part underneath the hood, as long as it is unpainted.

Step 4: Restart The Car And Check

Step 4: Restart The Car And Check
  • Run the car, then let it sit for a while.
  • Before attempting to start the other vehicle, give the battery at least 30 seconds to build up power.
  • If you want to direct additional power toward the dead one, press the gas pedal until the RPM reaches roughly 3,000.
  • Start the engine of the stranded automobile by turning the ignition key.
  • Check the cables’ alignment, turn off the vehicle, and then attempt revving the running vehicle to boost the power supply.
  • After numerous tries, if the car still doesn’t start, your car might be experiencing another issue. A fuse might have been blown, for example.
  • It is fine if the car’s lights turn on, but the engine won’t start.
  • In reverse sequence from the earlier connecting process, remove the cables. Look at the negative grounding cable you connected to the metal part first.
  • Remove the red and black clamps from the live (donor) battery, then tighten battery terminals.
  • Keep the car running so it can keep charging; otherwise, you’ll have to jump start it again.

Common Mistakes Of Using Cables

Battery put in backwards is only one of the common mistakes that many people make. It’s essential to get the knowledge about them so that you can avoid unexpected issues in the future.

  • Car battery hooked backwards: As explained in the above parts, this is extremely dangerous and will cost you money to solve the problem.
  • Cable ends touch together: Sparks can occur when the jumper wires are connected to a battery, and the cable ends are touched. The hydrogen gas escaping from it occasionally catches fire when the sparks are present, resulting in an explosion.
  • Jumping-starting a frozen battery: Never try to jumpstart a frozen one because doing so could result in an explosion. Before attempting to jumpstart the vehicle, take out the frozen dead battery, bring it inside, and let it thaw out.
  • Ignore safety protection: Gloves and goggles are the least gears you must have when performing battery operations. They will be really useful in unforeseen situations.
  • Ignore the attachment: Alligator clips that aren’t attached present a sparking risk if a cable connected to the active battery swings. Hold cables firmly to prevent loose clips from making contact with painted metal.
  • Leave the accessories turned on: Your car’s electrical system could experience a hazardous surge due to this error. Before jumping the battery, always turn off electrical equipment such as the lights, air conditioning, and other devices.

Final Thoughts

If you hooked battery up backwards now car won’t start, check our guidelines above. There are five common issues that you may have to face and fix.

Although troubleshooting at home is cost-saving, it’s dangerous as the battery can explode due to many causes.

For this reason, asking for help from experienced mechanics is highly recommended.

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