7 Differences Between AGM and Lead Acid Batteries

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It’s likely that the starting battery in your automobile is either an AGM battery or a flooded lead acid battery, both of which are forms of rechargeable batteries.

What, then, are the differences between these two batteries?

We will evaluate the AGM and lead acid batteries in this post to see how they compare.

Batteries: AGM vs. Lead Acid: 7 Important Differences

The AGM battery has its roots in the conventional lead acid battery, which should be noted before we start the comparison. They do, therefore, have certain things in common.

Now let us compare the differences between each sort of battery, starting with their internal mechanisms.

1. Time to Charge

AGM batteries with less internal resistance also charge faster. It is not as quick as a lithium battery when utilizing the same power source, but it may last up to 5 times longer than a flooded lead acid battery.

2. Discharge Depth

AGM batteries have an 80 percent depth of discharge (DoD), more than a flooded cell battery’s 50 percent DoD. As a result, AGM batteries are ideally suited to deep cycle applications.

Nonetheless, unlike the lithium battery, which may be fully depleted, it is not suggested to discharge any battery type below 50% of its capacity.

Note: Depth of Discharge specifies how much battery capacity may be safely drained without causing damage.

3. Tolerance to Temperature

AGM batteries operate better in all temperatures and have higher Cold Cranking Amp (CCA) ratings.

While frozen, the electrolyte in the glass mat does not expand like a liquid. As a result, AGM batteries are resistant to cold weather damage. So, while the battery will not likely operate in a cold environment, it will not fracture.

In the cold, however, flooded lead acid batteries will freeze. The battery plates have the potential to shatter, and the casings have the potential to expand and leak.

The flooded lead acid battery will evaporate more electrolytes in excessive temperatures, exposing the battery plates to air exposure (the lead plates need to stay submerged).

4. Overcharging Sensitivity

Overcharging tolerance is substantially higher in flooded lead acid batteries than in AGM batteries.

Because AGM batteries are sealed, they are more susceptible to thermal runaway, which can be induced by overcharging. Even if thermal runaway is ignored, soaking will significantly reduce the lifespan of an AGM battery.

When charging an AGM battery, utilize a controlled battery charger to keep the voltage and current in the battery under control.

Thermal runaway occurs when a battery creates more heat than it can disperse. In extreme situations, the battery will dry out and melt, releasing poisonous chemicals and causing fires or explosions. Nearby batteries will be impacted, perhaps causing a domino effect.

5. Life Expectancy and Self-Discharge

AGM batteries typically outlast ordinary lead acid batteries. AGM batteries also live longer than flooded batteries while not in use due to their low self-discharge rate.

A well-maintained AGM battery can last up to seven years, whereas flooded batteries typically last three to five years. If your car doesn’t start, you’ll know your battery is failing.

6. Sulfation and corrosion

Because it may vent acidic vapor and spill and leak electrolyte liquids, the flooded battery is more prone to rust than the AGM battery.

Both batteries, however, will sulfate if left discharged for an extended period. AGM batteries, on the other hand, are slightly more resistant, thanks partly to a slower self-discharge rate.

If you see significant corrosion on your battery terminals, it’s time to contact your mechanic about a replacement battery.

7. Cost-Effectiveness

As a starting battery for conventional autos, the flooded battery is cost-effective and dependable. AGM batteries can cost up to 2-3 times more than ordinary batteries.

Author: Sarah Sadie