How do I know what battery bank I need?

Batteries are an essential component of an off-grid or battery backup system, just as you use them to power electronics. This is the location where solar-generated electricity is stored. A good battery bank will meet your needs if you wish to use devices like your laptop, TV, and Wi-Fi router during load shedding. You will require more batteries the more power you require. We refer to a group of batteries that are connected to a system as a battery bank. In most cases, it is the most costly part of a power system. It’s critical that you get this properly the first time to save unwanted costs.

What kind of battery do need to I buy?

These days most people choose sealed batteries because they are easy to maintain. The following is based on the most popular sealed, reconditioned battery options.

1: Lead Acid Batteries

These are less expensive batteries, sometimes referred to as flooded or wet batteries, however, they typically have a 12-month guarantee. This battery will last for one to three years.

2: AGM Batteries

These are lead acid batteries as well, however, they are more efficient than their predecessors because of the upgraded technology known as Absorb Glass Mat (AGM) on the plates. They keep a charge quite well and charge very easily. If properly cared for, they last 4 to 10 years longer than normal lead acid batteries, while typically only having a 12-month warranty.

3: Gel Batteries

The reason gel batteries are named gel is that the acid inside the battery is changed into a thick liquid by using silica, also known as sand. Although they are more costly and highly exposed to outside factors, their performance is comparable to that of AGM batteries. A single error (overcharging or charging too quickly, for example) might do permanent damage. They have a greater depth of drain than AGM batteries, which is a plus.

4: AGM Batteries + Gel Batteries

These batteries utilize the positive characteristics of both Gel and AGM batteries to create a more efficient and longer-lasting battery. They are suitable for renewable energy systems and with long design life (8 to 12 years). They still come with the standard 12-month warranty.

5: Lithium Batteries

Lithium batteries, due to their light metal composition, have the highest energy density and can store more energy than other batteries. They can handle extreme temperatures and come with longer warranties and design lives, making them more cost-effective in the long run.

How is the AH rating determined?

I’m going to use the same load (stuff that needs to be driven) as an example of how to size a proper battery bank:

10 x 10W LED Lights = 100W

1 x LED SMART TV = 100W

2 x 30W Smart Phones = 60W

1 x Router = 20W

1 x Laptop = 65W

Total = 345W

Load shedding can sometimes last up to 5 hours per day, so 345W x 5hrs = 1725Wh or 1.725kWh. Since it is less than 2kWh, I can get away with a 12V system but prefer a 24V system so there is room for expansion.

We then use the basic Ohms Law to calculate the battery bank required:

Watts/ Volts = Amps
Watts/ Amps = Volts
Volts x Amps = Watts

Batteries are measured in Amp Hours so you will need to do the following calculation:

Watt hours/ Volts = Amp-hours
Therefore 1725Wh/ 24V = 71.88Ah
As you’ll recall, most batteries are only meant to be used at 50% capacity, so you’ll need to double the amp hours above, i.e. 71.88 x 2 = 143.76Ah.
Therefore, a 150Ah 24V battery bank would be suitable for the stuff you need to power.
As most of our Lead Acid, AGM, and AGM+Gel batteries are available in 12V cells, you will need 2 x 150Ah batteries connected in series to get 24V.
Series battery connections result in higher voltage, while parallel battery connections result in higher current.
Again, please keep in mind that these are the very basics of system design. There are many other factors that need to be considered, so please always consult a professional.

How can I efficiently maintain my battery bank?

Batteries should always be high off the ground. Battery boxes/cabinets are great for this. Plant them in a dry, ventilated area.
There should be at least 5 centimeters of space between each battery.
The inverter cables should be connected to the positive and negative terminals on both sides of the bank to ensure discharge. If it is connected to a battery, that battery will take strain and reduce the life of the rest of the bank.
Also for charge controller and battery charger cables, also for distribution of current.
You’ll need a 24V battery charger if you own a 24V bank. To prevent problems between the batteries, try not to charge each one separately using a 12V battery charger. Use a battery charger that is always the same voltage as the battery bank. Your batteries will sustain permanent damage if they are not the same.
Do not add an extra charge to the battery bank when you think there is enough storage to handle it. Battery banks are sized according to load as above. If you add additional accessories without proper knowledge of their function, and the battery discharges too low, you will damage your battery and greatly reduce its lifespan.
Investing in a battery monitor is a good way to actively monitor what is happening to your battery bank. This allows you to monitor the output state and quickly identify any issues that may arise.
Do not store batteries for more than 3 months. Batteries need to be charged so they don’t go flat. If they are being stored, take them outside and recharge them once a month to ensure longevity.

What more should I keep in mind before making a battery purchase?

Please always check the rating of the battery so that you can compare apples with apples. This is a description of the time it takes for the battery to charge or discharge. They are typically rated C10 (10 hours) or C20 (20 hours), but these vary from battery to battery. For example, a 240Ah battery rated C20 is the same as a 200Ah battery rated C10.
Check how many cycles are in the battery. Cycle refers to the number of times you can discharge and recharge the battery.
You pay for what you get. Batteries are the most expensive part of the power system and if you’re going cheap, don’t expect them to last very long.
For your own safety, please research a company before choosing its service. There are many startups that do not have the technical knowledge to effectively help you with your needs, and batteries can be dangerous if they are not suitable for your needs or installed correctly. are The Internet is not counted as a reliable source of information.

Conclusion:

Ultimately, there are many factors to consider and think about to determine the right battery bank for your needs. First, review your electrical needs, including the devices you want to charge or power and their energy consumption. Second, consider the capacity of the battery bank, making sure it can meet your needs without frequent recharging. If you plan to utilize the battery bank while on the go, you should also take its weight and flexibility into account. In order to guarantee long-term use, take into account the battery bank’s dependability and safety features. You can choose the battery bank that best meets your demands and guarantees continuous power whenever and wherever you need it by carefully considering these elements.

FAQ’s:

What is a battery bank?

A battery bank comprises interconnected batteries to provide a larger capacity and voltage.

What is the formula to calculate the battery bank size?

Battery Bank Size (Ah) = Total Wattage (W) x Number of Hours (h) / Voltage (V) x DOD (%).

How do I determine the size of the battery bank I need?

Consider the total watts and voltage of your system, the number of hours you want your appliance to run, and the depth of discharge (DOD) you prefer.

Can I mix different battery types or ages in a battery bank?

It is advised to use the same batteries in order to guarantee the best performance and durability.