How to Resuscitate a Deeply Discharged AGM Battery?

How to Resuscitate a Deeply Discharged AGM Battery

To resuscitate a dead AGM battery that just won’t take a charge from a smart battery charger or car’s alternator, you’ll need to conscientiously follow the steps put down below. Here a complete process of restoring a deeply discharged AGM battery is given.

The problem with the AGM battery is, if you let it discharge deeply, you may probably never get them to pick up the charge again. It’s really challenging to do for a long discharged AGM battery. However, we’ve found you a solution for this problem. Follow this and you may get your AGM battery back to pick up charge again.

How to Resuscitate a Deeply Discharged AGM Battery?

The complete process of rejuvenating a deeply discharged or dead battery is shown below step by step.

This process tricks the battery charger to assume it’s charging a good battery, while the real thing is, it’s charging a dead battery though a good battery.

Tools and Equipment You’ll Need

  1. A 12 and half+(plus) Volt working-Battery (AGM or Wet Cell battery will do)
  2. Your car’s dead AGM Battery
  3. Battery Tester
  4. Smart Battery Charger
  5. Jumper Cables
  6. A Handwatch or Timer
Resuscitate a Deeply Discharged AGM Battery

Step 1: On step one, put on your rubber gloves, and put up your battery tester on the deeply discharged battery to see the condition of the battery. Showing low means there is not enough charge in the battery for the battery charger to kick in and start charging the battery.

Step 2: After determining the battery is too low on power, take a well-working battery that is at least 12 ½ + volt. You may take it from another car or any spare battery will do the job. 

Step 3: Double check the working battery with the battery tester to ensure if the voltage is on point. If it shows more than twelve point half it should be good to go!

Step 4: Now, you’ll have to connect the batteries parallelly. But before that unhook the AGM battery you have in the car. You need to unhook the negative or the ground strap first. Keep the charger disconnected when you connect the batteries.

Step 5: Use a set of jumper cables and put or black clamp first on the negative side of the working battery, and not to connect the positive end yet until you hook the dead battery. Now, connect the black wire of the opposite side to the negative side first on the dead battery, then the red wire to the positive side of the same battery.

When you’ve connected the both sides of the dead battery with jumper cable, get back to the working battery and connect the red wire on the positive pole. Make sure all the terminals are tight enough. In short, positive to positive, and negative to negative.

Resuscitating process of a Deeply Discharged Battery

Step 6: As now you have the both batteries connected to each other through jumper wire, the very next step will be to hook the smart battery charger up to the working battery before you plug it in. follow the positive to positive and negative to negative procedure, but the positive one first here.. Now plug the charger in. The charger will come to life. In short, connect the leads to the terminals of the working battery.

Step 7: On this step, you’ll have to go through the settings of the battery charger for your dead car battery. Set the charger for a medium sized battery. You may have options of 2, 10, and 15 Amps. Set it to 10 amps or whichever suitable for your car’s AGM battery. On the next row you’ll see Standard, AGM, or Gel call. You’ll have to go for the AGM battery.

Step 8: The charger will notice the voltage of the working battery and charge it. It will show the energy flow in volt, and the percentage of charge it currently has on its little red monitor. If the battery is not kicking back let it sit for an hour and get back later.

Step 9: Now, turn off the charger and disconnect from both of the batteries. Then put the tester on and measure the volt of the rejuvenated battery.

  • If the tester shows a volt less than 10.5, repeat all the previous steps.
  • If it has a 10.5+ volt, charge your AGM battery as you normally do.


***It is OK if the battery is warm at the point of charging. But if it gets too hot to touch, or if you hear a hissing, STOP CHARGING RIGHT NOW! Overheating or hissing noise indicates there might be something wrong within the battery. Let the professionals handle it.

Safety Precautions

*Use rubber gloves.

*Wear eye protection.

*Be careful while handling positive and negative wires.

Frequently ask Question about Deeply Discharged AGM Battery

What is an AGM Battery?

AGM or Absorbent Glass Material batteries are sealed Lead-Acid batteries that are spill-proof and more reliable than typical Lead-Acid batteries. These batteries are lighter than the traditional one and hazard free.

How Do You Recognize an AGM Battery?

These advanced LA batteries are leak-proof, has minimal gassing, and 

There is a label that identifies if it is an AGM battery. These labes are typically printed as: ‘AGM’, ‘Absorbed Glass Material’, ‘Dry Cell’, ‘Non-spill’, ‘Sealed Regulated Valve’, ‘Regulated Valve’ etc.

What’s a Trickle Charger?

Trickle chargers are basically used for charging a battery slowly, preventing it from overcharging. When you store a battery for a long period, it’s worth it to invest in a trickle charger to prevent the battery from deep discharge damage.


May this article have helped you to resuscitate a deeply discharged or dead AGM battery. Make sure to follow all the safety protocols to handle the dead car battery and recharging it. However, you can always call for professional help in case of emergency. So, don’t delay when you really need help.