How To Resuscitate A Deeply Discharged AGM Battery?

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You’ve got a deeply discharged AGM battery. What now? If you don’t want to pay $100+ at the auto parts store, then you’ll need to try some DIY methods to resuscitate it.

A deep discharge occurs when a battery has had its charge depleted too far. This means that the electrolyte inside the battery has dried out and become unusable. The result is that the battery won’t start or run properly anymore.

AGM batteries are used in vehicles and many devices, including cell phones, cameras, laptops, tablets, etc. They are also known as deep-discharge batteries because they are designed to hold a charge for years before being fully discharged.

Most people will tell you that AGM batteries are dead. But that’s not the case! In fact, they are very resilient and can last for years with proper care.

To fix a deeply discharged battery, we’ll go over how to revive these old batteries and bring them back into action. 

3 Ways To Resuscitate A Deeply Discharged AGM Battery

If you’ve ever had a deep discharge problem, the solution is to resuscitate them. Here are three ways to fix an AGM battery. These methods work well. Let’s dive in!

1. DIY Solution

This method lets you charge an old battery without damaging it. The main principle is to trick the charger into thinking there is still enough charge left in the battery.

For this purpose, you need some tools that are probably in your garage. You will need a timer or watch, a voltmeter, 12V+ another working battery, a battery charger under 15 amps, jumper cables, and a discharged AGM battery.

  • Firstly, Check the voltage of the deeply discharged battery with a voltmeter to evaluate its condition before starting the work.
  • If you find the battery power is too weak to operate, now take the fully charged working battery and connect it with the discharged one in parallel, positive to positive and negative to negative terminal with jumper cables. Now check whether the voltage level is high enough to charge the second battery.
  • Now you must connect the 10-amp charger to the working battery and turn it on. It will check its voltage and start charging the deeply discharged AGM battery. 
  • After an hour, check if the AGM battery is warm or hot. If it is too hot to touch or produces a hissing sound, then stop the charging process by removing the charger. There could be some issues with the battery. However, if you find it’s warm, that means all is doing well.
  • Check the voltage of the AGM battery. If it’s above 10.5V, it’s a normal process.
  • After getting a good voltage reading, disconnect the charger from the good battery and then connect it to the AGM battery only. 
  • Continue the charging process until your discharged AGM battery is fully charged. To avoid damage, don’t overcharge the battery.

That’s it. You’ve resuscitated the AGM battery at home.

2. AGM-Specific Charger

If you want to recondition your AGM battery without having to buy a whole new one, there are several options out there. One of the most popular ones is the AGM Battery Reconditioner Kit. However, while it does work well, it is expensive. If you don’t mind spending a few extra dollars, here are three alternatives that cost much less.

The first alternative is the AGM Battery Recharge Station. While it doesn’t come with a specific AGM battery charger, it does include a universal charger that will recharge almost any type of lead-acid battery. You just have to make sure that the battery is compatible with the charger.

Another option is the AGM Battery Maintenance System. This system includes everything you need to keep your AGM battery charged and ready to go. It also includes a maintenance tool that allows you to clean and check your battery.

Finally, Smart AGM chargers are the perfect solution if you want to save money and still enjoy great performance. These chargers are very versatile and will help you achieve maximum output from your batteries.

There are many different smart and specific AGM chargers available, so shop around and see what works best for you.

These AGM-specific chargers are designed to provide maximum performance. They can initiate the desulfation process to regain power. They work as both battery maintainers and trickle chargers. Some have ring terminals, so you don’t have to worry about connecting them permanently.

They charge deeply discharged batteries faster than traditional chargers. Charging rates depend on the charger’s ampere output. This is a good way to figure out how much time you’ll spend charging if you buy a new car battery charger. Most chargers have a maximum ampere output of about 12 amps.

3. Find a Professional Battery Specialist

If you’ve got a deeply discharged or dead battery, the easiest thing to try is to simply replace the battery yourself. There are plenty of DIY options. Most people aren’t qualified to do a proper job. But even the most basic car repair shops won’t be able to do it properly.

Well, the best option is to find a professional battery specialist who knows AGM technology and can recover it or replace your battery safely and effectively. These specialists usually offer a wide variety of services, including charging, testing, and replacement.

They can also tell you whether your battery needs to be replaced entirely or if it just requires a simple charge.

But how does an expert know exactly which tools to use? Well, he has access to a variety of equipment, including a defibrillator, a suction device, and a tool called a sump pump. These items allow experts to perform their jobs safely and effectively.

The same goes for AGMs. An AGM battery is made up of two cells connected together. Sometimes, these cells discharge too quickly and cause damage to the battery itself. This can lead to a dangerous situation where the battery explodes and causes serious injury. So, how do you prevent this from happening?

Well, you can use a tool like a sump pump to remove excess water from the battery. Then, you can replace the battery with a fresh one. Once this process is complete, you can charge the battery using a charger designed specifically for AGMs.


How long does it take to charge a completely dead AGM battery?

The average time for charging a completely dead AGM battery is about 5 to 6 hours. This depends on how much power is left in the battery, and whether the charger has been used previously. It also depends on the type of battery, its age, and its size.

How to tell if an AGM battery is bad.

If the AGM battery has been stored for a long time, then it may be damaged. The best way to check whether the AGM battery is working properly is to charge it up and test it. If it shows a 20% lower voltage than the fully charged voltage level, it may be due to replacement. Also, If the charging process takes longer than normal, then the battery needs to be replaced.

If you need to know how to test a car battery, then you should check out our guide here.

Can an AGM battery be rejuvenated?

Yes! The best way to rejuvenate an AGM battery is to charge it at least once a month for 30 minutes. This will ensure that the electrolyte remains fresh and the cells do not dry out. If you want to learn how to recharge your batteries safely, check out our guide here.


In conclusion, batteries are incredibly useful devices. They store energy and provide power for our devices, like charging our phones or powering our cars. However, like anything else, batteries eventually wear out. When that happens, they become useless and must be replaced. Fortunately, there are plenty of ways to revive a deeply discharged battery without having to replace it entirely.

The first step is to ensure that the battery has sufficient charge left to last through its normal lifespan. This can often be done by using the charger provided with the device. If this doesn’t work, however, you can use a trickle charger instead. These chargers slowly drip a small amount of current into the battery for hours, gradually restoring its capacity. Once the battery is fully charged, it can be used normally.

Another option is to remove the battery from the device and connect it directly to a wall socket. While this won’t restore the battery’s original capacity, it does allow the battery to recharge itself. Depending on the type of battery, this process can take anywhere between several days and several weeks. Afterward, the battery can be reinserted into the device and used as usual.

Lastly, we can call upon the services of an expert to help us resuscitate our AGM batteries.