It's stone dead for one of two reasons: first they only last 4-6 years, so if it was older than 2-4 years when you parked it, it was doomed anyway. Second, leaving a battery to sit for 2 years like that is very rough service for a lead-acid battery, so even a halfway healthy battery wouldn't have survived it.
As for your spare vehicle's spare battery: a new, unused car battery can often sit unused for two to four years and still work—as long as it's properly stored and maintained. For maximum shelf life, be sure to: Store the battery upright. Keep it in a dry, well-ventilated area.
Batteries gradually deteriorate until they can no longer provide enough power to start an engine. This wear time could take three to five years and a vehicle's usage pattern is one factor contributing to the rate at which a battery will age.
How Long Can a Car Battery Sit Unused? How long does a sitting car battery last? A car battery can last about four weeks to two months before it dies. Your car battery can only last so long before it fails when you're not driving because of key-off drain.
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 answer can vary depending on your car battery age, type of vehicle, and the weather. Typically, your car can sit about four weeks to two months without driving before the battery dies.
No, you can't charge a car battery while idling. At best, it'll charge the battery a few amps, but not nearly the hundreds of amps it took to start the engine. After a few days of starting and then idling the engine, you'll steadily deplete the battery instead of charge it.
If kept in a charged state when unused, the common lifespan of a 12-volt Gel or AGM battery is up to six years. After five or six years of float voltage at an average ambient temperature of 25 ºC, the battery still retains 80 % of its original capacity.
Some cars will get up to five or six years out of their battery, while others will need a new one after only two years. In general, your car will usually need a new battery after three to four years. Replacing your car battery is another part of routine maintenance.
Extreme temperatures, frequent short trips, and general everyday use could shorten the life of your battery to two to three years. If your car battery dies quickly, even after a jumpstart, it might be time for a new one.
If your battery is 3 or more years old, it will likely need a replacement to avoid repeated failure. While you may be able to get it going with a jump-start, the catalyst for its initial failure is still threatening the lifespan of your battery. It will likely continue to die until you get a replacement.
Q: Do batteries expire? A: Yes, all good things must come to an end. To find the Best If Used By (BIUB) date of the batteries in question, please look on the uppermost section of the cells, near the battery type (AA, 9V, etc.). You will see a white box with the Best If Used By year printed within it.
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.
This voltage range means the battery is in good condition for starting the vehicle. If the measured reading is less than 12.2 volts, the battery's resting voltage is weak, which means it most likely needs to be charged or replaced.
12.0 volts or below - At 12.0 volts your battery is considered to be fully discharged or 'flat' and should be recharged as soon as possible. The lifespan of your battery will be severely affected if it remains within this voltage range for extended periods of time.
Using a Voltmeter to Test Your Battery
Start the ignition while holding the leads on the positive and negative terminals. You will notice that the voltage will drop, but it should not drop below 9.5 volts. It needs to be replaced if it drops below this voltage.
If your battery is sulfated, which results in low power and difficulty in recharging to full capacity, it can sometimes be recovered using proper pulse charging techniques. Wehmeyer warns, however, that there are an infinite variety of pulse charging techniques used by a wide variety of equipment sold for this purpose.
One common reason why a car won't jump start is because the battery is completely dead. 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.
Car batteries are expensive components in your car. A good thing is the fact you can recondition them and end up with a new battery. The main fact you should know is that a reconditioned battery will have up to 70% of the power of a brand-new unit, but this is more than your car needs.
As your car sits, the battery is still powering everything from alarm systems to your car's onboard computer systems. This is called parasitic drain. If you let your car sit long enough, this parasitic drain will use up the battery's entire store of power, leaving you with nothing to turn over your engine.
There are some reasons a car battery may not hold a charge. The most common cause is that the battery is old and needs to be replaced. Another possibility is that the battery has been damaged by heat or cold. If you think your car battery is not holding a charge, it is vital to take action.