Flat Battery vs Dead Battery: What's the Difference?
Imagine that you're all set to leave, and suddenly find out that your car is not starting due to a flat or dead battery. Well, it may seem sudden to you but is not in most cases.
It takes frequent deep discharges, leaving your car exposed to extreme climates, or other factors over a period for these issues to arise. Hence, It is crucial to maintain a car battery to prevent it from dying or going flat.
To save you from the hassle, I will discuss the differences between a flat battery and a dead battery and how to diagnose issues of each.
What is a flat battery?
A battery is referred to as flat or drained when it loses its charge because of regular use or various other factors. Simply put, a flat battery has some power left, but it's insufficient to start your vehicle.
One common reason your battery may go flat is when you try to draw more power than it can provide. Or, if it is left unused for a long time. Faulty alternator diodes and exposure to extreme temperatures can also drain your battery's life.
However, in most cases, the battery is not unusable. You can recharge a flat battery, so it can start powering your devices and vehicle again.
What is a dead battery?
When a battery has lost all its capability to store a charge permanently, it is called a dead battery. Unlike a flat battery, a dead battery cannot be revived and must be replaced.
This can be due to the battery's maintenance negligence for a long time or significant internal damage. Additionally, faulty charging systems, manufacturing defects, and corrosion on battery terminals can also cause the battery to die rendering it unusable.
So, how would you know if your battery is dead? Some key indicators could be the unresponsive engine and dim lights, and even worse no functioning at all, when you start the car.
Older vehicles or ones used in harsh environments are often more likely to have dead batteries.
Flat battery vs dead battery: What's the difference?
Are you confused about whether your battery is dead or flat? If you are about to get your car battery replaced, you must know if it's really dead or has just gone flat. This way, you may not have to get a new one and save money.
Here are the key differences between the two issues.
Charge storage
A flat battery holds some power but is not sufficient to start a car. While a dead battery has permanently lost its charge and fails to supply any power.
Potential for recovery
A flat battery, in most cases, can be revived by using a battery charger or jump-starting it. On the flip side, a dead battery cannot be recovered and must be replaced with a new one.
Electrical components functionality
If a battery is flat, some vehicle components like lights or dashboard indicators may still work poorly. A dead battery, however, will not be able to provide any power to these electrical systems, so they won't function at all.
Response to load
When connected to a vehicle, a flat battery will provide insufficient power, which results in clicking sounds or slow cranking. With a dead battery, you will see no response from the engine as you attempt to start it.
What causes flat and dead car batteries?
There are several reasons a battery may go flat or dead. There are ones you can control and some unavoidable like a very old battery. Let's dive into what causes these issues.
Causes of flat car batteries
- If a vehicle's interior lights or headlights are left on for too long, such as overnight, the battery can go flat.
- Exposure to extremely cold temperatures can impact your battery's ability to generate electricity, as it can slow down the internal chemical reactions.
- The alternator recharges your car battery while the engine is running. Improper functioning of the alternator can lead to a flat battery.
- A car left unused for a long period can also cause a flat battery.
- Taking very frequent short drives doesn't give the alternator enough time to properly charge the battery, hence insufficient power supply.
Causes of dead car batteries
- Manufacturing faults can sometimes give you a dead battery. If your new car battery has suddenly died, it likely happened because of a defect in the product.
- A defective or incompatible charger can overcharge your battery which will lead to overheating leading to significant internal damage.
- Deep discharges can cause the formation of sulfur crystals on the battery plates which reduces its ability to hold charge. Multiple deep discharges can lead to a dead battery.
- Physical damage to the battery casing such as cracks can expose internal components of the battery to environmental factors or cause a leakage of electrolytes. This speeds up the degradation of the battery.
- A common cause of dead car batteries is the end of their lifespan, which is inevitable.
How can a flat battery progress to a dead battery?
One of the reasons a flat battery can progress to a dead battery is that it is left uncharged for a long time. If you don't recharge a flat battery for an extended period, its capacity decreases, hence a dead battery.
Additionally, if a flat battery is damaged physically, for instance, its casing cracking can also result in a dead battery. Excessive self-discharge in flat batteries can damage their internal components rendering them dead.
As a battery approaches the end of its life, its internal components start dying. This degradation gradually causes the battery to lose its ability to hold a charge, leading to a dead battery.
How can you diagnose flat and dead batteries?
To test whether a car battery's dead or flat, you don't necessarily need to take it to a mechanic. This can be done at home using a voltage meter or a battery tester.
How to diagnose a flat battery?
1. Using a voltmeter
First, you'll need to measure the voltage throughout your battery's terminals. Then, compare the reading with the voltage level specified by the manufacturer. If it is lower than that specified value but within the acceptable range, your battery has gone flat.
2. Using a battery tester
You can use a battery tester to check out the battery's health and the state of charge. If the tool shows a low charge, this indicates a flat battery.
3. Visual indicators
When connected to a load or a vehicle, a battery's performance can indicate if it has gone flat. To diagnose this issue, look for dimming of interior lights or headlights, faint horn sound, or a cracking engine that fails to turn over.
How to diagnose a dead battery?
1. Voltage rating
A dead battery shows zero voltage rating on a voltmeter. Use a reliable voltmeter to see if the voltage reading across battery terminals is zero.
2. Response to load
No response to load indicates a dead battery. For instance, a car's engine shows no response when you try to start it or the electrical components such as interior lights or radio don't work at all. If your battery displays these signs and doesn't respond to jump-start attempts, it's most likely dead.
Tips for maintaining flat and dead batteries
Follow these tips to maintain your battery and prevent it from dying or going flat.
- Avoid too many short drives and take longer ones instead, as it lets the alternator recharge your car. Even if you are planning to park your car for a longer period, disconnect the battery or get a battery maintainer.
- Check your battery when you lift the car bonnet for any corrosion signs or leaks. Also, Get other battery-related systems inspected such as the alternator and starting and charging systems to diagnose any problems early on.
- If your battery has gotten old and is reaching the end of its lifespan, consider replacing it.
- Prevent undercharging or overcharging by using the correct amp settings and charging voltages.
- Regularly monitor battery health and voltage level to identify problems early.
- In extremely hot weather, park your car in a shaded area, and in very low temperatures. You may also use battery blankets or insulation.
Conclusion
Diagnosing whether you have a flat or dead battery is crucial to take appropriate measures and prevent any unexpected breakdowns. When comparing a flat battery to a dead battery, the key difference is the charge levels. A flat battery holds some charge, while a dead one does not at all.
Alternator issues and excessive discharges like leaving car headlights on for long can cause a battery to go flat. A battery can also die due to significant internal damage or overcharging.
Make sure you follow the manufacturer's maintenance guide, avoid frequent deep discharges, and don't let your battery get exposed to extreme temperatures to avoid dead and flat batteries.
FAQs
Should I replace my car battery if it is flat?
In most cases, you don't need to replace your car battery if it is flat. Simply recharge it and you'll be good to go. To recharge a flat battery, attach the charger to your car battery making sure the clamps are connected to appropriate terminals. Then, plug in the charger and turn it on.
Some chargers automatically shut off once the battery is fully charged, while others let you know when the job is done. Once the battery is charged, turn off the charger and disconnect it to avoid overcharging.
What happens when a battery goes flat?
When a battery goes flat, it no longer holds a sufficient charge, which means it cannot start your car and will need recharging.
Even though a flat battery's power won't be enough to turn over a car engine, it can provide some electricity to the car's electrical systems, such as radio, doors, interior lights, etc., which may result in dim lights and a cranking engine that struggles to start.
Will a completely flat battery recharge?
Yes, it is possible to recharge a completely flat battery by using a battery charger, push start, or jump start. However, the time it will take depends on various factors, including battery capacity, the type of charger you use, and discharge level.
