Can I recharge a completely dead sealed lead acid battery. Agm battery dead

Can I recharge a completely dead sealed lead acid battery?

Sealed Lead Acid batteries fall under the category of rechargeable batteries and if they are ignored, not charged after use, not charged properly or have reached the end of their intended life span, they are done.

If it’s completely dead, it’s gone and you need to find a replacement. If you are lucky and there is enough juice left, you can hook it up to a Smart battery charger and get more life out of the battery while desulfating the lead plates and bringing it back around.

Complete the charge/ use cycle five times to see if this will remove the sulfur efficiently enough to restore performance to the battery. To do this, fully charge the battery, use the battery until it is depleted, then repeat this cycle five times.

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Hopefully you get lucky and can get more use out of the battery if it’s not critically damaged.

On the negative side, the longer after initial use it sits without operating or the longer into its life span, the less of a charge it will hold if any. When the battery is new, it should be at 100% capacity, meaning it is holding the full charge it was intended to.

Batteries that sit for a length of time after use without a charge or that are near their intended lifespan will perform badly as well as lose the ability to hold a full charge. Instead of holding 100% capacity, it will gradually drop down to 90%, 70%, 40%, etc. until it is dead.

The best practice to extend the life of your battery is to give it attention, especially during those winter months. It can’t sit idle for a length of time and be expected to perform when needed.

I recommend using a Smart charger (trickle charger) to allow the battery the chance to maintain itself and give you the most bang for your buck when not operating.

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How to safely and quickly recharge a dead car battery

Whether you’re on the road or still in your own driveway, realizing your car battery is dead is always an inconvenience. The risk of finding yourself with a dead battery is higher in the winter, since the cold temperatures can be very harsh on your vehicle.

If you end up with a dead battery, whatever the season, follow these tips to safely recharge it.

What Causes a Dead Battery?

Many things can lead to a dead battery, including the following:

  • Loose or corroded battery connections
  • Extremely hot or cold temperatures
  • Taking too many short trips
  • Leaving the lights on for too long

Many of these causes can be avoided, especially with proper maintenance. But a dead battery isn’t always preventable. Thankfully, unless it’s severely damaged, it’s easy to get your battery up and running again.

Inspect the Battery

The first thing you need to do is inspect the physical appearance of your battery for signs of damage. Always wear gloves when doing this.

If you notice any cracks or leaking battery acid, do not attempt to recharge it. If you see some corrosion but the rest of the dead car battery looks okay, start by cleaning it with battery cleaner and a battery terminal brush. Once the battery is cleaned off and its cables are secured, you can jump-start your vehicle.

How to Jump-Start Your Car

Before you can recharge your dead car battery, you need to jump-start it. Follow these steps:

  • Position a functional vehicle next to the one with the dead battery. The vehicles should be close enough for the jumper cables to reach between them without the vehicles touching each other.
  • Turn off the car with the functional battery.
  • Open the hood/compartment on each vehicle where the battery is located.
  • Connect one end of the positive jumper cable to the dead battery, then connect the other positive end of the cable to the charged battery. The positive and negative terminals on the battery will be indicated by plus and minus (-) symbols.
  • Connect one end of the negative jumper cable to the negative terminal on the charged battery and the other end of the cable to a grounded metal component on the car with the dead battery, like the frame or chassis.
  • Turn on the car with the charged battery.
  • Leave the cars connected for at least five minutes.
  • Try starting the vehicle with the dead battery. If the battery has enough power, it should start without any problem. If the vehicle doesn’t turn on, wait another five minutes before trying again.
  • Once the car with the (previously) dead battery turns on, disconnect the jumper cables in the reverse order you connected them:
  • Remove the negative cable first by disconnecting the grounded end from the frame or chassis, then the other end from the negative terminal on the battery. Next, remove the positive cable by disconnecting it first from the car that supplied the boost and then from the previously dead battery.

What Condition Is It In?

After jump-starting your vehicle, determine how dead the battery is before you try to fully recharge it. You can do this with a voltmeter or multimeter.

A healthy battery should read between 12.4 and 12.7 volts. Your battery’s voltage will determine how you should charge it after jump-starting your vehicle.

Above 12 Volts

If your battery is between 12 and 12.4 volts, you can recharge it using your vehicle’s alternator. Simply drive around while using as little electricity as possible. That means no stereo, no lights (don’t do this at night), and no heating or A/C. Conserving electricity this way will send as much energy as possible directly to the battery.

Avoid idling when using this charging method. After a 30-minute drive, your battery should be sufficiently charged for next time you start up.

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How to Troubleshoot Deep Cycle Battery Issues

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Maintaining your deep cycle batteries is essential to ensure a maximum life span and to prevent damage. As such, it is important to detect battery problems at an early stage. Troubleshooting deep cycle battery issues is fairly easy to do yourself with the aid of a multimeter, volt meter, or watt meter.

Inspecting your deep cycle battery

The outside of deep cycle batteries can show early signs of failure. As such, troubleshooting battery problems can begin with a simple inspection. Ensure that the top of your battery is clean and dry. When a battery is covered in dust and dirt, it can discharge across the grime. Also, inspect the battery for broken or loose terminals; they are dangerous as they may result in short circuits. Flooded deep cycle batteries will need to be checked for leaking and damaged battery cases that may have been caused through overcharging or overheating. This problem won’t occur with AGM deep cycle batteries as they are designed with glass mat technology preventing leakage, even when damaged. Generally, cracks and holes will not prevent deep cycle batteries from operating, but they can be unsafe. As such, it is recommended to discard any batteries that have reasonably damaged battery cases.

Before testing your deep cycle battery

It is suggested to test your battery’s life when it is fully charged. If you find yourself in a situation where you cannot charge the battery, let it sit for approximately one hour before testing. As a result of charging or discharging, an uneven mixture of acid and water can arise on the surface of the plates. This phenomenon is referred to as a ‘surface charge’, and will need to be removed before the testing begins as it may influence your data. Surface charge can make a bad battery look good and vice versa. To remove the surface charge you can simply leave your fully charged deep cycle battery to sit for at least four hours. Also, ensure your battery is not connected to any appliances or a battery charger as this will influence the data.

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Note: if you have multiple batteries connected together, each battery should be disconnected and charged/tested separately.

Testing the voltage of your deep cycle battery

You can test your deep cycle battery’s charge level in several ways. The most common methods use a multimeter, voltmeter, or watt meter. When you decide to test with a voltmeter, we recommend using a digital meter rather than an analogue meter as it will be more accurate in measuring millivolt differences. For a detailed guide on how to test the voltage of your deep cycle battery, you can have a look at our video ‘How to Check Your Battery Charge Level and Troubleshoot Issues’.

Analysing the test data

Once you tested your deep cycle battery’s voltage, you can analyse its state of charge. Simply compare the measured voltage with a state of charge table to discover your battery’s estimated charge level. For example, if your AGM deep cycle battery rates at 12.30V, it’s at a 70% state of charge as shown on our State of Charge graphic. This charge graphic relates to 12V AGM deep cycle batteries, but can also be used as a general guide for other battery types though keep in mind that there may be slight differences in the voltage rating.

Typically, a fully charged deep cycle battery will have a voltage of over 12.8V. 13V. Below are a few common battery problems you can identify by the voltage measurements.

If a fully charged AGM battery tests more than 20 percent lower than the fully charged voltage level, it’s probably due for replacement. This is typically a symptom of battery age, damage from over/under charging, or sulfation. You can sometimes improve a battery in this condition by using a desulfation device, otherwise you’ll have to live with the low capacity or replace the battery.

If your battery shows a good voltage when it’s fully charged, but quickly drops voltage to 11V or less when using power, this usually means the battery has a faulty cell and needs replacement. This can be caused by excessive vibration such as driving over corrugations without adequate shock absorption for the battery, or a manufacturing fault. Faulty cells are difficult and usually impractical to repair, so you’ll need to replace the battery.

When a deep cycle battery is fully discharged (dead flat), it should reveal a reading of approximately 10.5V. If your test shows that this voltage is below 10V, this typically means that the battery has been left in storage for too long without a charge or left with a load running on it that doesn’t have an automatic cut-off. Once a battery is below 10V, it is difficult to bring it back up as most battery chargers won’t recognise it as a battery due to the very low voltage. You can sometimes bring a battery back up by using an old bulk battery charger with no smarts (one that you just switch on, and it starts powering away with no stages or battery detection), but this usually depends on how long the battery has left at this low voltage.

Some final suggestions

Although you can easily troubleshoot any different battery issue yourself, accurately testing a deep cycle battery’s capacity requires a ‘deep discharge’ test. This kind of test can only be done with specialist discharge testing machines that can be found at reputable battery stores.

When troubleshooting a battery bank set up with a series or parallel circuit and one of the batteries is faulty, it will pull all the other batteries down. For example, if one of your batteries has dropped down to 8V, you may notice that the other batteries within this bank will have low voltage ratings as well. To troubleshoot this, you’ll need to disconnect and perform a full test on each battery individually. The battery with the lowest rating will be the faulty battery that needs to be replaced.

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When your deep-cycle battery nears end-of-life, it’s normal to want to squeeze as much out of it as possible before spending money on a new one. Numerous online videos show a variety of ways to revive a dead or dying battery using various substances and hacks. The truth is, there are many factors that contribute to poor battery performance and failure, and it is important to diagnose the symptoms of poor battery performance before determining a cure. It is also important to understand that many of the supposed “cures” can damage the battery, while others can be dangerous and do nothing to improve battery performance.

Fred Wehmeyer, Senior VP of Engineering at U.S. Battery, has more than 50 years of experience in rechargeable battery design and development. He says that many of these hacks claim to show some type of improvement, but the gains shown may simply be artificial. One of the more common ones is adding Epsom salt to the battery cells. According to Wehmeyer, adding Epsom salt (magnesium sulfate) to a lead-acid battery will ‘artificially’ increase the specific gravity reading (SG), but because it does not increase the sulfuric acid concentration, it does nothing to improve battery performance.

“This is because the sulfates in the Epsom salt are tied up as magnesium sulfate and are not available for discharge to lead sulfate as the sulfates in sulfuric acid are,” said Wehmeyer. “If you filled a new lead battery with a magnesium sulfate solution instead of sulfuric acid electrolyte, it would have no capacity at all.” Simply put, adding Epsom salt will not recover the battery capacity but does “artificially” increase the SG.

According to Wehmeyer, the result would be similar if you remove the dilute electrolyte from a discharged and/or sulfated battery and refill it with the electrolyte for a fully charged battery (usually 1.270). The specific gravity will be higher, but the battery plates are still discharged and/or sulfated. Doing this will probably kill a potentially recoverable battery (see below).

Baking Soda and Aspirin

Other popular hacks include adding baking soda to recover a dead battery. Baking soda mixed with water is often used to clean the tops of batteries and battery terminals because it neutralizes the sulfuric acid and acidic corrosion products. Wehmeyer says that pouring baking soda into the battery cells will neutralize the sulfuric acid in the electrolyte to sodium sulfate that cannot discharge to lead sulfate in the normal discharge reaction. This will also permanently reduce the capacity of the battery, which was most likely already low.

Adding aspirin to the battery is another hack that is often seen in videos claiming to revive dead batteries. Wehmeyer says aspirin is acetylsalicylic acid, which eventually breaks down into acetic acid. Acetic acid attacks the positive lead dioxide plates in the battery and permanently damages them, leading to short battery life. This may show a small, temporary increase in capacity but will quickly kill the battery.

Pulse Charging

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. These techniques include DC (direct current) pulses using various voltages and currents, as well as AC (alternating current) pulses with a wide range of AC frequencies. “The problem is that if not done properly, it can do more damage than good,” says Wehmeyer. “Having said that, I have tested some very complex and very expensive pulse chargers that appeared to recover sulfated batteries more quickly than traditional methods. Most pulse chargers use an external power source (wall AC) to power the device. Some, however, use the battery’s voltage to power the charge pulses. This can kill the battery if left connected for long periods of time without a separate charger.”

Ultimately the best recommendation for potentially recovering a sulfated battery is to save your money and try using a long, slow charge. If you have a battery charger that has a reconditioning or equalizing charge mode on it, that may be your best bet. “Use the equalization charge mode regularly, about once a month, on deep-cycle lead-acid batteries to extend the life of the battery,” says Wehmeyer. “Regular equalization charges prevent sulfation and stratification by balancing the individual cells and properly mixing the electrolyte. In addition, a long slow charge could help recover already sulfated batteries to make them last a little longer. If your charger does not have an equalization charge mode, simply wait until the charger completes a normal charge and then restart it by unplugging AC power and reconnecting. The charger should continue charging for an additional 1 – 3 hours. If the battery is dead from poor maintenance, worn-out from too many deep cycles, overcharging, or excessive deep discharging; it probably can’t be recovered.”

Following manufacturer-recommended care and maintenance procedures will get you the longest life and best performance from any battery. For more information on how to care for your lead-acid batteries, check out the U.S. Battery User Manual.

The content opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag

US Battery

U.S. Battery Manufacturing Company

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