Last Updated on July 19, 2023 by Bernard Juchli
Car trouble can come from various sources, and the causes are often intertwined. However, the battery and the alternator play key roles in the operation of your vehicle and are often sources of problems. Therefore, this post addresses the signs of a bad car battery Vs alternator to help you determine why your car won’t start.
While a car battery provides power to start the vehicle, the alternator generates power to keep it running, while also charging the battery. So, you want to identify the signs of a bad car battery versus an alternator to help diagnose and fix the issue before it results in more serious problems.
Difference Between Car Battery and Alternator
Your vehicle’s battery and alternator function in power delivery, yet they serve differently. Although there is some overlap in their roles, each is vital at different phases of your car’s operation.
What Does a Car Battery Do?
Consider your car’s battery to be akin to a morning cup of coffee — it provides the necessary energy to kick-start your vehicle. When you insert and twist your key to ignite the engine, it is the battery that transmits power to your starter, ignition coils, and other critical parts.
While batteries are capable of providing a considerable burst of electrical energy, they cannot typically maintain a vehicle’s operation independently. This is where the alternator steps in.
What Does an Alternator Do?
After your vehicle has started, the alternator assumes the responsibility of recharging your battery and powering nearly all of the vehicle’s electrical systems. It simply converts mechanical energy into electrical energy through a belt and pulley system.
Inside the alternator, a set of magnets attached to a rotor spins within a stator whenever the alternator’s pulley rotates. This action generates direct current (DC) electricity, effectively overcoming the constraints of the battery’s limited capacity.
Signs of a Bad Car Battery Vs Alternator
Here is an easy way to think about starting your car: first, your battery gives power to the starter, which gets your engine going. Next, your engine running triggers the alternator. Last, the alternator charges up your battery again.
Now, how do you find out if there’s a problem with your battery or alternator? Try jump-starting your car. If your car starts but then stops right away, it might be your alternator not charging your battery properly. If jump-starting gets your car going and it stays on, but it won’t start again later by itself, it might be your battery that’s dead.
So, let’s consider the signs of a bad car battery Vs alternator by breaking it into two sections, one for each component (battery and alternator).
Signs of a Bad Car Battery
When your vehicle refuses to start, the battery is often the primary suspect given its pivotal role in the vehicle’s electrical circuit. Think about whether you’ve encountered any of the subsequent indicators recently.
1. Difficulty in Starting Your Car Regularly
Should your car display a pattern of cranky starts, evident through a clicking noise and a delay in the ignition, your battery is likely losing its charge.
However, extremely cold weather can hinder your car’s prompt start-up. If you’re living in a colder climate and observe difficulties in starting your car, it might be the weather and not the battery at fault.
2. Evident Battery Corrosion
Acid leakages can lead to corrosion in car batteries. This acid comprises hydrogen gas which, upon interacting with the air under your hood, transforms into a green, blue, or white substance.
This corrosion can obstruct the startup of your car since it serves as a barrier between the battery and the rest of the vehicle’s electrical system. This leads to two primary problems regarding signs of a bad car battery Vs alternator:
- The battery can’t dispatch sufficient energy to ignite the engine.
- The alternator fails to deliver enough energy to recharge the battery.
On the bright side, you can prolong your battery’s life by cleaning the corrosion until you can procure a new one. This involves detaching the battery and using a battery cleaner and wire brush to remove the corrosion. You can purchase the cleaner from a store or make a concoction of baking soda and water.
However, remember that if you notice corrosion, your battery is leaking, signaling an imminent replacement need.
3. The Car Fails to Retain Charge Over Time
You might have noticed that your older mobile phone doesn’t retain its charge as efficiently as when it was new. That’s due to the natural degradation of batteries over time, and your car battery is no exception.
The age of the battery is a significant determinant, but another aspect is whether you’re adequately recharging your battery every time you drive. Short drives might not provide enough time for the battery to recharge, impairing its future charge retention ability.
If you’ve recently relied on a few jump-starts, it’s a strong sign that your battery is on its way out.
4. Flickering Electrical Systems in Your Car
When your vehicle is switched off, the battery continues to power the electrical systems. A faulty battery will find it hard to maintain these systems, leading to potential issues like dimming or flickering lights or inconsistent radio signals.
5. Vehicle’s Low Voltage Indicator Turns On
Modern vehicles are equipped with computer diagnostics to alert you when the electrical system is underperforming. Still, keep in mind that the activation of this indicator denotes a malfunction in the electrical circuitry, which is not necessarily linked to the battery alone. The issue could stem from the alternator or another element of the electrical grid.
6. You Detect a Smell of Rotten Eggs Emanating from Your Battery
In normal conditions, your battery should not emit any odor. But if the battery’s sulfuric acid overheats, it transforms into hydrogen gas, which produces a smell akin to rotten eggs.
If you pick up on this scent, it’s crucial to seek immediate professional assistance. This is not just a sign of a failing battery but also an explosion risk that could potentially harm nearby individuals.
7. Battery Appears to be Bulging
Car batteries contain hazardous substances, such as sulfuric acid, which are generally safe unless overheated. Overheating could cause the battery’s casing to bulge. If you observe this upon opening your car hood, refrain from touching it.
Instead, promptly call a tow truck and avoid trying to replace the battery yourself, as it may explode. While battery replacement is generally a straightforward task, this situation demands professional intervention.
8. Car Battery Has Exceeded Its Lifespan of 3-5 Years
Typically, car batteries last between three to five years – Capital One. The presence of extra electrical accessories like subwoofers, auxiliary lights, or alarm systems can affect this lifespan. If you’re aware of the last time the car battery was replaced and it’s been beyond this typical lifespan, the aging battery is likely the reason behind your car struggling or failing to start.
Signs of a Bad Alternator
Having considered bad battery indication in relation to signs of a bad car battery Vs alternator, let’s consider those signs of a failing alternator:
1. Vehicle’s Low Voltage on the Dashboard Turns On
Just as with your battery, if your vehicle has a low voltage icon, it may light up if there’s a problem with the alternator.
2. Car Vibrates While Driving
The alternator has the crucial task of generating the electricity needed to ignite the spark plugs. These spark plugs are essential for igniting the fuel, creating the energy that propels the car’s wheels. If a spark plug fails to ignite, the engine falters, leading to a palpable vibration while driving.
3. Electrical System Problems
The alternator is bad if you notice peculiarities with your vehicle’s electrical system, particularly affecting the radio and both interior and exterior lights. If your car’s electrical system starts to malfunction, your alternator may be the culprit. You might spot one or more of the following irregularities:
- Dimmer or excessively bright interior and exterior lights
- Exterior lights brighten as your speed increases
- The radio, particularly on the AM setting, produces a whining or static noise, or intermittently cuts in and out even within a station’s range
4. Car Fails to Start With a Jump-start or Initiates but Shuts Down Shortly After
The alternator maintains the car’s operation once the battery completes its initial function. If a jump-start does not work, or if the car starts but shuts down within 10-15 minutes, this could signal that the alternator is failing to support the electrical system or not recharging the battery.
5. Squealing/Growling Noise from Your Engine
A squealing or growling sound from your engine, especially when electrical systems like the radio or headlights are operational, suggests an issue with the alternator.
However, when you hear such noises, you want to consult a professional for a thorough examination. that’s because these sounds can also be symptomatic of other problems, such as a deteriorating serpentine belt or another malfunctioning component, such as the power steering pump or air conditioning compressor.
6. A Burning Rubber or Hot Wire Smell from the Engine
In some cases, a faulty alternator might overcharge the battery rather than neglecting to charge it altogether. This scenario is often accompanied by the smell of burning rubber or hot wires while the car is running.
7. Alternator is Between 7-10 Years Old
Contemporary alternators generally endure for about 7 to 10 years before requiring replacement. According to the Savannah Toyota, most alternators will last between 80,000 and 150,000 miles — or about seven years.
If you’re aware that the alternator hasn’t been replaced during this period and you’re noticing some of the aforementioned signs, have a professional inspect your alternator before your car begins to stall or develop starting issues.
What if the Car Won’t Start?
If you prefer not to conduct your own diagnostic tests, initiate a jump start (while ensuring the vehicle stays running) and let a technician perform an inspection of your electrical system. Both the start and charge systems warrant examination.
Standard wet-cell battery assessments should encompass a review of the fluid level, an inspection for corrosion on the terminals (the posts marked + and -), and a check of the cables for secure connections and corrosion-free conditions.
An electronic battery test is recommended as it provides more data than a typical load test, by measuring the voltage and cold cranking amps (CCA). (Note: Battery inspections and charges are complimentary at Les Schwab Tires.)
Additionally, the service center should evaluate the alternator’s voltage and current output and inspect for any signs of faulty diodes, which are responsible for transforming the electrical current from AC (alternating current) to DC (direct current). If it’s time for a replacement and your vehicle is equipped with power-demanding aftermarket accessories such as a sound system, consider inquiring if a higher-capacity alternator is needed.
If the alternator is functioning correctly, the investigation will progress to other components of the starting and charging system.
Can You Drive with a Bad Battery or Alternator
It is simply not safe to drive with a bad battery or alternator. While your car might drive temporarily, it can trigger a chain of problems affecting other areas of your car, including the engine and electrical subsystems.
Moreover, the battery will eventually exhaust its reserves, leading to your car’s failure. If you don’t have the necessary equipment to jump-start your car or if you’re in a secluded location, this could result in getting stranded.
The vehicle’s power steering could also fail, causing you to lose control. Therefore, for your safety and that of others on the road, address any battery or alternator issues ASAP.
Contact Your Local Mechanic
Now you know the signs of a bad car battery Vs alternator. If any of the symptoms surface, or if your vehicle has surpassed its recommended maintenance period, turn to the expert technicians in your local community. You need professional evaluation to get to the root of the issue. Professionals can typically also help with replacing your battery or alternator, if needed. So, make sure to secure your appointment ASAP.