AGM Vs. Lithium Batteries

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The last few decades have seen a rise in battery technology. This has given us several different choices when it comes to choosing the right types of batteries for various applications. While there are a lot of different types of batteries to choose from, two of the most popular choices are lithium-ion and AGM. While these are both great battery choices, they do have some significant differences. Before choosing a battery, you need to know what they are and how they differ.

AGM

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AGM batteries are based on the older lead-acid style of battery. However, they are not quite the same. Old-school lead-acid batteries worked by converting water to sulfuric acid, which is contained within the battery. These batteries were heavy and prone to leaking if left for too long. AGM batteries are based on a similar principle, but they are built differently. The acid is stored in fiberglass fibers within the battery – in fact, AGM stands for “absorbent glass mat.”. This fiberglass mat means that there is no liquid to spill, and no liquid to weight down the battery.

Lithium-Ion

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Lithium-ion batteries are batteries that work by passing lithium ions back and forth between electrodes. These batteries were developed as a fossil fuel-free alternative to the traditional battery. They are lighter and more efficient than most batteries out there.

Between these two choices, there are some significant differences. Although lithium batteries tend to outscore AGM batteries in many applications, it doesn’t mean you should blindly choose one over the other without first knowing what to look for.

The Differences Between AGM and Lithium-Ion

1. Charge Efficiency

Charge efficiency refers to how long it actually takes to charge a battery. Due to internal resistance, charging a battery is not an even, steady process. Batteries begin charging quickly, but the fuller the battery gets the slower the charge. This means that a battery can become partially charged relatively soon, but it takes a much longer time before the battery will approach 100% capacity.

In this area, lithium-ion batteries are superior. With all other things being equal, and AGM battery can take up to four times as long to charge fully. This is due to a much higher internal resistance that significantly slows down the charging process in AGM batteries as the battery begins to fill. Lithium-ion batteries, on the other hand, also have internal resistance, but much less. So, in this case, lithium batteries are the clear winner. 

2. Weight

This is another area where lithium batteries win. While different batteries have different weights, when you compare similar batteries based on usage needs (in other words, how many batteries it would take to perform a task) it becomes clear very quickly that lithium batteries are much lighter than their AGM counterparts.

For single-battery applications, this weight difference might not matter too much. However, when you are requiring an entire battery pack for larger applications, the difference in weight really adds up.

3. Capacity

Energy capacity is another important factor to consider. In this case, “energy capacity” refers to how much energy a battery can actually hold, and ultimately deliver, on a single charge.

Again, the lithium battery wins. When looking at similar battery set ups, it becomes clear very quickly the lithium-ion batteries can store and delivery more energy on a single charge. This might not matter quite as much is you are using a battery for a stationary application where you can easily recharge it again, but if you are on the go, or hoping to get the most use out of a battery on a single charge, then this becomes increasingly important.

Not only does this mean you can get more out of your battery, it also means that you don’t need a more complicated, multiple-battery setup that can weigh more and drive up your costs.

4. Cost

So far, everything we’ve seen points towards lithium batteries as being the clear winner, but there is one area where AGM batteries are better, and that’s cost. Much like other lead-acid batteries, AGM batteries cost quite a bit less than lithium-ion batteries do. 

However, this is where you have to take your battery needs into consideration. If you only need one battery, then the cost difference might be enough to go with the AGM. However, if you need multiple batteries, or are going mobile, then you have to look at how many batteries you will end up needing. Since lithium batteries are lighter and more efficient, you can get away with taking less batteries with you. This can also impact your cost quite a bit.

Conclusion: Which Is Better – AGM or Lithium?

So, now that we’ve looked at the differences, we come back to the original question:which is better. All in all, it’s almost not even a contest: lithium batteries win in almost every category worth looking at. The one major advantage AGM batteries have over their lithium-ion counterparts is cost, but even that might not be as much of a factor when you start looking at how many batteries you need, and what you are going to be doing with them.

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