3 Easy Ways To Charge A Dead AGM Battery

Here are 3 easy ways to charge a dead AGM battery. Unfortunately, most AGM batteries will reach a point of decline and die. But, before you throw your old AGM battery away it is possible to revive it.

This guide will show you how to revive your dead AGM battery in 3 easy steps, so you can recondition your AGM battery yourself.

In a lot of cases, your AGM battery is deeply discharged rather than dead or faulty. If this is the case then your charger won’t be able to detect the minimum voltage in the battery so it doesn’t know what to do.

The design of AGM batteries means that there is minimal internal resistance and so the battery can perform high power tasks regularly and be very responsive. But, this same feature means that they can also deeply discharge when left for long periods.

Charge a dead AGM battery

3 Easy Ways to Charge a Dead AGM Battery

If your AGM battery is deeply-discharged, try these methods to revive it before getting a new one.

Use An AGM-Specific Charger

Purchasing an AGM-specific charger is the easiest way to revive a deeply discharged AGM battery. 

AGM batteries have to be charged long and slow with a low current setting. Using a standard charger can negatively affect the performance of the battery, which could end up costing you more then a AGM-specific charger.

An AGM battery charger will ensure that the battery is charged correctly and prevent any damage. It does this by intuitively adjusting the voltage and current to stop the temperature from getting too hot during charging.

An AGM-specific charger is specially designed to start the desulfation process within the battery. Sulfation is the formation of lead sulfate crystals in the cells of a battery, this occurs when batteries are not fully charged. Therefore it’s important to reverse this before the battery can be charged.

These battery chargers are becoming increasingly popular as they help maintain all lead-acid batteries with the desulfation setting.

If you do decide to purchase one of these modern chargers then you can use them as a battery upholder too. Get a model that has ring terminals (additional leads) so it can stay attached to your battery permanently. This makes it easy to hook it up to recharge your battery.

Charge a dead AGM battery

DIY Solution

If you don’t want to purchase an AGM-specific charger you can try tricking your standard battery charger into charging the AGM battery. 

To do this you will need the following:

  • Battery charger under 15 amps
  • Jumper cables 
  • Voltmeter (also known as a multimeter)
  • Another good battery that is more than 12.2 volts
  • Stopwatch

Step 1. Take the batteries, the good one and the AGM that needs charging. Connect the jumper cables to each battery, positive to positive and negative to negative. 

Step 2. Connect the battery charger leads to the good battery and turn the charger on. The charger will start charging the battery after checking the voltage, and via the cables will start to slow charge the AGM battery. Leave this on for about an hour.

Step 3. Keeping checking on the system, feel the AGM battery to check that it has warmed up. If it is warm (even just a little bit) this is a good sign, and means that it is getting charged. There is a problem if the charger or battery is hot, turn the charger off immediately and disconnect the batteries.

Also listen closely, if you hear any hissing or gas leaking turn off the charger because there is a problem.

Step 4. After a few hours of the system running, use the voltmeter to see how many volts the AGM battery has reached. You are looking for 10.5 volts before you can disconnect, it will take a few hours for it to reach this level.

Step 5. When the AGM battery has reached 10.5 volts you can disconnect the charger from the good battery. Continue charging the AGM battery until it’s fully charged.

Your AGM battery should be charged and ready for use.

Charge a dead AGM battery

Get Help From An Expert

If the above options fail or you’d rather not risk doing the charging yourself you can get expert help. 

The third option available is to seek professional advice and assistance to revive the AGM battery or buy a new one.

Most battery centers will do a free diagnostic check on your battery, they will use their specialist equipment to test the battery. Make sure that they know it is an AGM battery and it is deeply discharged.

Ask them if they can try to resuscitate it even if they say it’s dead, they will have the AGM-specific chargers to do this. This will work most of the time if the center won’t try to consider going to another one.

Final Thoughts

Don’t give up on your old AGM battery before you’ve tried these techniques to revive it. It is always worth trying to revive your dead AGM battery before you buy another one.

Once you have successfully resuscitated your AGM battery, try to keep it connected to a battery maintainer to prevent it from becoming dead again. This will increase its performance and keep it in a better condition for longer.

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