Introduction

An AGM battery voltage chart describes the relationship between voltage, current, and the state of charge using recorded values. 

Further understanding these relationships will help make sense of your solar system’s components.

Let’s go over why so many people are opting for AGM batteries to use in their solar systems.

AGM Battery Charge Voltage Chart

AGM batteries fall under the category of lead acid, along with wet or flooded cell batteries. Yes, they’re both lead-acid, but there are distinct differences between the two. 

Flooded or wet-cell batteries are the most affordable option on the market. Lots of maintenance is necessary to ensure this battery lasts its lifetime. 

This includes regular equalization charges and checking the water levels. 

These batteries are known to emit hydrogen gas, ventilation will be required to remove the fumes.

Many people use this type of battery in their portable off-grid solar system because it is so inexpensive, but they eventually switch to lithium after wet cell becomes problematic. 

So if you’re planning to use a solar panel voltage chart, you’ll notice that an AGM battery outperforms.

AGM lead acid batteries are fitted between two fiber glass mats, allowing the electrolytes to be absorbed.

Since the battery is sealed, it requires less maintenance. 

In almost every category, these batteries outperform wet cell batteries. These are the best lead acid batteries in terms of charge cycles and overall weight.

Before we get into what an AGM battery charge voltage chart, let’s look at why so many people opt for these batteries. 

Advantages of AGM Batteries 

The unique design of AGM batteries allows them to deliver faster start-ups and an increased cold cranking power compared to your conventional lead acid batteries.

Their absorbent glass mat cell offers rugged durability and improved vibration resistance, as well as being spill and leak-proof. 

This is all due to the electrolyte being held within the mat instead of moving around in liquid like the flooded cell.

AGM batteries also excel in their repeated charging and discharging capabilities, so when we have a battery discharge voltage chart, we use an AGM battery.

AGM batteries have the capacity to absorb the recycled energy from breaking quickly and handling the excess energy without overcharging. 

These batteries drain at a much lower rate than conventional lead acid batteries.

AGM batteries are designed to withstand deep and repeated discharges.

The acid cannot escape from the AGM batteries due to the glass wool, and because gas discharge is minimal, it can also be installed in living spaces. 

They require no maintenance and do not require water to be replenished. In other words, these batteries will work perfectly for your solar system.

They’re also appropriate for use in the applications like camping, motor boats, and for  uninterrupted power supplies.

AGM Battery Charging Voltage Chart

Different charging or discharging currents have an effect on battery voltage when charging or discharging.

This means that the higher the current, the higher the voltage when charging. The higher the current in a discharging condition, the lower the voltage.

The battery’s voltage can be affected by the different manufacturers and production materials used in the hardware.

The battery's voltage varies with temperature. This means the lower the temperature, the lower the voltage.

The battery voltage will be reduced after a period of use and all AGM batteries have the same voltage discharge curve. 

That is why, by measuring the voltage and consulting the voltage discharge chart, we can use the voltage state of charge charts to determine how much energy is left in the AGM battery.

12-Volt AGM Battery Voltage Chart

When looking at the 12V AGM battery chart, the state of charge voltage of a 12V AGM battery ranges from 13.00V at 100% capacity to 10.50V at 0% capacity. 

If you measure the 12.30V voltage on your 12V AGM battery, for example, you can determine that this 12V AGM battery still has 70% capacity.

24V AGM Battery Voltage Chart

In the AGM 24V lead-acid battery voltage chart below, the voltage ranges from 26.00V at 100% charge to 21.00V at 0% charge with this higher voltage 24V deep cycle battery.

The absolute voltage difference between a full and an empty battery is 5.00V.

If you use a voltage meter and measure the difference between the cathode and anode of an AGM battery to be 23.50V, you can read from this chart that this 24V battery still has 20% to 30% charge left.

48V AGM Battery Voltage Chart

The voltage ranges from 52.00V at 100% charge to 42.00V at 0% charge with a high voltage 48V deep cycle battery.

The absolute voltage difference between a full and an empty battery is 10.00V.

If you use a voltage meter and measure the difference between the cathode and anode of an AGM battery to be 47.00V, you can read from this chart that this 48V battery still has 20% to 30% charge left.

AGM Battery Discharge Voltage Chart

An AGM battery’s ability to discharge deeply without any damage to the plates is a definite advantage for those wanting to use it in a solar system.

Charts and curves are commonly used to depict discharge.

We need to look at the depth of discharge to understand it. This is the percentage of power that can be drawn from a battery.

If we have an AGM battery with a depth of discharge of 45%, the load can only use 45% of the battery's capacity.

In other words, your 300Ah battery can only produce 165Ah at a depth of discharge of 45%.

When a load is connected to the battery, the battery drains because the load draws current from the battery.

Battery discharge can be defined as the process by which a battery completely loses its charge.

The battery drains faster as the load draws more current.

Since different batteries are used for different purposes, we can use two different discharge periods to measure them.

Using the battery pack rating in the graph below, you can discover the discharge current for your battery in the same way that you’d use a 48V battery discharge chart. 

Simply get the Ah rating on your battery and look at the corresponding column.

Which AGM Battery to Choose for Your Solar System?

Choosing a battery size that works best in your system depends on its size.

If you want to power an RV, then opting for a 12V deep cycle battery for solar is perfect.

The 24V AGM batteries are perfect for home solar systems that are in relatively sunny areas. 

Lastly, the bigger 48V AGM battery will suit those with a big home or a small farm.

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