Difference between AGM, Lithium Ion and flooded batteries

It’s the age-old question: which one is better: AGM, Lithium Ion or flooded batteries. While they are often pitted against each other, it’s important to note there are quite a few similarities. The debate often gets heated but first let’s break down what exactly all options entail, how they differ from each other and which one will serve you best on your battery back up or off Grid project.

What is an AGM battery?

Traditionally used as a car battery, with recent advanced developments have allowed deep cycle AGM batteries to be paired with solar panels. AGM, Absorbent Glass Mat, Batteries use glass mats that act as a separator that wicks electrolytes between the battery plates. This material’s design enables the fiberglass to be saturated with electrolyte – and to store the electrolyte in a “dry” or suspended state rather than in free liquid form. This sealed battery is maintenance free and unspillable.

Pros:

Known as the Maintenance Free batteries, AGM batteries require little to no maintenance to perform optimally
Great option if storing in a hard to reach area where maintenance is difficult to perform

Cons:

Very sensitive to charging. The performance of these batteries and their lifespan can be affected whether over or under charged.

Best use with solar: AGM batteries are best paired off-grid systems with weather extremities. AGM batteries are more efficient in Manitoba winters.

What is a Lithium Ion battery?

The technology dating back to the 1970’s, lithium batteries aren’t by any means new to the market. You can find lithium ion batteries in everyday rechargeable items such as your cell phone, AA batteries and electric vehicles. Lithium ion batteries may cause some initial sticker shock, however, their top notch efficiency will give you more bang for your buck as you will spend less per kilowatt-hour of capacity over its lifespan.

The recommended battery chemistry for solar is Lithium Iron Phosphate, shorted to LiFePO4 or LFP batteries. This new technology lasts longer and can be put through deeper cycles. They also require no maintenance or venting, unlike lead-acid batteries.

Pros:

Higher depth of discharge: The DoD of a battery is the amount of the stored energy in the battery that has been used, as compared to the total capacity of the battery. Most batteries come with a recommended DoD in order to maintain the health of the battery.
Lithium-ion solar batteries are deep cycle batteries, so they have DoDs of around 95%. Many lead acid batteries only have a DoD of 50%. This means you can use more of the energy that’s stored in a lithium-ion battery without having to charge it as often.
Less maintenance: A priceless feature, no regular maintenance needed here
Lifespan: While it’s no secret that all batteries degrade over time, Lithium-Ion consistently has outlasted their competitors time and time again. Factors like a larger depth of discharge make lithium-ion batteries more resilient and help these batteries go up to six times the life cycles of AGM alternatives.
Capacity: Lithium batteries contain a higher energy density which means it can store more energy per mass than AGM. Essentially systems can be smaller, and lighter but still carry the same output.

Cons:

Cost: A heftier upfront cost for long term savings.
Lithium ion batteries are very sensitive to charging below the recommended temperature.

Best use with solar: Residential battery backup system in Manitoba. Lithium batteries are generally smaller, more compact and have a higher Depth of discharge (which means you can use more stored energy). In a controlled environment, where its operational temperature parameters can be respected, Lithium Ion batteries thrive.

What are Flooded batteries?

Considered the most traditional of the three, Flooded batteries use a liquid electrolyte-containing medium to trigger a chemical reaction. When the battery is connected, the battery acid bonds to the lead plates. This causes a reaction that sends an electric current through the attached circuit. These batteries are high maintenance and must be taken care of to perform at its most optimal level.

Pros:

Most cost effective when its compared with its competitors
While flooded batteries do require maintenance, if taken care of properly this battery type will last longer than many of their counterparts.

Cons:

Unfortunately due to the fact it contains free liquid, it requires regular maintenance and inspections
Needs to be handled with extreme care
​​Extreme climates can have a greater effect on the battery life due to the electrolyte solution inside the battery having the ability to evaporate or freeze.

Best use with solar: Best paired with off grid solar projects in Manitoba. These batteries cannot handle freezing temperatures, let alone to Manitoba winter deep freeze. Therefore, they are best paired with off grid 4 season homes where the batteries are not exposed to freezing temperatures and planned maintenance is able to be carried out.

There is no tried and true answer to which battery is best for you, it really boils down to what your goals are, the application of the project, the budget you are working with and the long term plan for your solar installation. Hopefully this article provided you with a little more clarity on the different types of projects available on the market, and as always we are happy to help you navigate the best options for your project.

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