Flooded Lead Acid Batteries: The Best Lead Acid Battery?

Flooded lead acid batteries are the most commonly used solar battery. First used for vehicles like golf carts and forklifts, flooded lead acid (FLA) is one of two types of lead acid batteries used in solar power systems.

The other type of lead acid battery is the sealed lead acid battery (SLA). Both batteries have the same size, weight, efficiency and performance.

The key difference between flooded lead acid batteries and other batteries is that they’re the only battery that requires maintenance to keep them working properly.

If you’re new to lead acid, check out my beginner’s guide to lead acid batteries for the basics.

Are flooded lead acid batteries a good solar battery?

Flooded lead acid batteries are the cheapest solar battery. They have the lowest cost per amp-hour and cost per kWh cycle of all deep cycle batteries. The upfront cost is up to 2-3 times less than lithium batteries.

Features of flooded lead acid batteries.
Flooded lead acid battery features.

Flooded lead acid is a “wet” battery. This is because the battery’s cells are submerged in distilled water. The water needs to be replaced about once a month as it depletes when you use the battery. Not topping up the water reduces the battery’s lifespan.

The battery also needs an equalizing charge once every three months. This is a controlled overcharge that research shows helps extend the battery life.

An equalizing charge and refilling the water is the key maintenance you need to perform on a flooded lead acid battery.

Another key thing to know about a flooded lead acid battery is gassing. This is a chemical reaction that happens in the battery in which it releases hydrogen as a by-product.

Flooded lead acid batteries must be kept in a well-ventilated area to allow the hydrogen to escape. The hydrogen is potentially explosive in an enclosed area.

Gassing happens about once a month and it’s the reason the water in the battery gets depleted.

If properly cared for and discharged to only half of their capacity, FLA batteries can last from 4 to 8 years.

Check out this guide to sealed lead acid batteries to find out how long they last.

Should you get a flooded lead acid battery?

Flooded lead acid is cheap. This makes it an attractive option if you’re looking to buy solar batteries. But should you choose them over sealed lead acid or a lithium battery? There are certain specific situations where it’s worth it to go with flooded lead acid over the other options. These are:

  1. If you just want battery backup in case of load shedding or blackouts.
  2. For everyday use in an off-grid home.

Pros and Cons of flooded lead acid

To summarize, let’s look at the pros and cons of flooded lead acid.

Advantages of a flooded lead-acid battery

  1. They’re cheaper than lithium.
  2. Longer lifespan than sealed lead acid batteries.

Disadvantages of flooded lead-acid battery

  1. Require maintenance.
  2. It can only be installed upright. Sealed lead acid can be installed on its side which can sometimes take up less space.
  3. Gassing poses another potential safety problem.

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