When Is A Dead Car Battery Truly Dead? A car battery is considered fully discharged at 11.9V. However, if the voltage drops to around 10.5V, the lead plates are likely almost entirely covered by lead sulfate. Discharging below 10.5V can permanently damage the battery.
As such, a dying battery puts a big load on the alternator. This will overload the alternator and damage it. As a result, the battery and alternator generally need to be replaced together.
"If your car does not start after a jump, your battery is likely completely dead and will need to be replaced. Your choices are to call for a towing service to bring your car to a repair shop or your residence, or roadside assistance, which may make their own attempt at jump-starting.
If a battery is completely dead but has been revived by a jump start, there are ways to fully recharge your battery. The first is, as mentioned, by driving around. If that does not seem to work, however, car battery chargers can regenerate all of the charge into a battery.
Even though 80 percent of the capacity remains when a car battery dips to around 10.5 volts, the battery is considered to be fully discharged because taking the cycle any deeper will cause irreversible damage to the plates through excessive sulfation.
Typically, your car can sit about four weeks to two months without driving before the battery dies.
A battery might need replacement if its volts suggest it's gone bad. As your battery ages, it loses its capacity to hold an electrical charge. An old battery can cause some identifiable issues, especially when you're starting your car.
Driving with a dead battery is only recommended if you are driving it straight home and It's always best to get a battery replaced before any issues can arise.
If the battery is completely dead, it won't have enough power to turn over the engine, even with a jump start. In this case, you'll need to replace the battery to get your car running again. Another reason why a car battery won't jump is because there is a problem with the charging system.
The most common way to deal with a dead battery is by jump-starting it. All you need to jump-start a car is a set of jumper cables and another car (a good Samaritan) with a functional battery. Keep in mind that you should never try to jump-start a car if its battery is cracked and is visibly leaking acid.
If your battery is over 4 years old we'd advise replacing it with a new one. You may find you're able to temporarily recharge a battery this old, however it's likely to lose its charge again very soon. Older batteries do deteriorate over time and naturally lose their ability to hold a charge.
What if your car won't jump-start? First, try running the other engine for five more minutes before trying again to start yours. If your car still doesn't start, you may need a new battery — or it could be a sign of a more serious problem.
Your car battery could die.
Unfortunately, when your car sits idle for weeks or months, the battery has nothing to charge it and it could eventually die as a result. Need help jumpstarting your dead car battery? We've got you covered.
The battery will charge faster if you rev the engine faster. Why? Because the faster the crankshaft turns, the faster it turns the belt that runs the alternator. And the faster the alternator turns, the more electricity it produces to run all the electrical stuff in the car — and recharge the battery.
“Electrical devices or lights left running, a defective charging system or alternator, and extreme weather are some common reasons but maybe it's just time to get a new battery.”
Can I Recharge A Dead Car Battery? Often, a “dead car battery” simply means that it's fully discharged and the voltage is below functional 12V. You can jump-start the dead vehicle and drive it to let the alternator replenish the battery charge. Alternatively, you can attach the dead battery to a battery charger.
Since cells do not produce energy, they do not have any other mechanism to charge themselves. Simply put, no car battery, whether healthy or dead, can charge itself. It always requires an external power source to get charged.
If you have jump-started your car, it is recommended to let your vehicle run for at least 30 minutes because it would typically require at least half an hour to charge a dead battery entirely or at least sufficiently.
Although most car batteries are sealed and maintenance free, they do usually have a water level indicator that will allow you to observe if the water level is good. Low water level means the electrolyte will be out of balance and the battery cells will become too acidic resulting in sulphation on the battery plates.
Overwatering. Not only can your battery have too little water to function properly, but it can also have too much. Overwatering can cause the electrolytes to become diluted, which results in diminished battery performance levels.
A battery with low battery fluid levels also gives signs you shouldn't ignore. Slow crank/no crank starting condition, dimming lights, alternator or battery light flickering on, other electrical problems or even the Check Engine Light illuminating can point to battery problems.