Backyard Wind Turbine Batteries

Now that your wind turbine is up and running let’s look at how to connect batteries to your backyard wind turbine. This is the system that will store the clean energy produced by the wind turbine. Then convert it into useful electricity you can use. Making the system is pretty simple. All you need to do is source the batteries and connect them to each other. Then connect one end to your charge controller. The other end is connected to a power inverter. This converts the stored energy into useable electricity.

We will cover the charge controller and inverter in another post which you can find here. This section will help you with the more difficult part. Like what type of battery to use, what voltage and capacity to use and what orientations to arrange them in.

Battery Types


Let’s start with what type of battery you should use. The different types of chemical energy storage you can consider are lead-acid, lithium-ion, hydrogen and flow batteries. Here’s a brief overview of each of the different technologies that can be used to connect batteries to your backyard wind turbine.

Lithium-Ion

Lithium-ion batteries are one of the most popular energy storage options. Today they are widely used in phones, laptops and cars. They have a high round-trip efficiency of about 99%. An energy density in the range of 250 Wh/kg and capable of withstanding just under 2000 cycles before fading. The popularity of the Lithium-Ion battery has led to advances in technology. It now is outperforming the other types of battery with respect to energy density, power density and round-trip efficiency. The image below shows a schematic of a typical lithium-ion battery.

Schematic of Lithium-Ion Battery



Lithium-Ion batteries are one of the most expensive types of batteries. They are nearly six times as expensive as lead-acid batteries. If you choose this option your investment cost will be high. The higher costs are associated with the materials use and the manufacturing process. There are also concerns about the disposal of spent lithium batteries as can release toxic material. So if you’re trying to be environmentally conscious with your project this is something to consider.


Lead-Acid

The lead-acid battery is the oldest, cheapest and most mature form of chemical energy storage. Deep-cycle lead-acid batteries are ideal for small-cycle renewable energy integration applications. These batteries can be discharged repeatedly by as much as 80% of their capacity. So they are suited for grid-connected systems where users sell power back to the grid. They have low investment costs and relatively low maintenance. Making them one of the most suitable batteries for small-scale wind energy projects. The image below shows a typical lead-acid battery.

Schematic of Lead Acid Battery (Photo credit: circuitdigest.com)


Limited cycle life and poor performance at low and high ambient temperatures are a pitfall of this technology. But it is the cheapest and most widely available battery and can be bought in your local motor factor store. Like lithium-ion, lead-acid batteries are environmentally unfriendly and toxic materials make it a hazardous product to dispose of when spent.


Hydrogen Energy Storage

A hydrogen fuel cell uses electrolysis of water process to produce hydrogen and oxygen. Excess electricity from a power generation source supplies the electrolyser (reverse fuel cell), splitting water into hydrogen and oxygen). The hydrogen can then be stored in compressed gas or liquid form. When electricity is needed, H2 is supplied to a fuel cell which converts the hydrogen and oxygen back to electricity and water. Or directly to a gas turbine as a combustible fuel. A schematic of a hydrogen fuel cell is shown below.

Schematic of a hydrogen fuel cell


Hydrogen-based energy storage systems are receiving increasing attention today, particularly in relation to their integration with renewable power sources. Hydrogen fuel cells have several advantages including high energy density and large storage capacity. It is still a costly method of energy storage. But has one of the lowest round-trip efficiency ranges of 20-50%. It would be hard to source for a small-scale energy storage system. You can consider this battery and make use of if you can source them priced reasonably.

Connecting your batteries

Once you’ve decided on a battery technology the next thing to look at is the voltage and amperage. The most easily sourced battery sizes are 12V and 24V which are perfect for your single backyard wind turbine project. Now let’s consider the amperage. The batteries can come with a range of storage capacities. The capacity of a battery is measured in amp-hours. Say if you get a battery that is 12 volts and has a capacity of 10 amp-hours. You’d probably want to connect 10 together in parallel to up the storage capacity to 100 amp-hours. This would be perfect for your small-scale project. The higher storage capacity of your system the more energy you will readily have on hand. So there really should be no cap on the storage capacity of your system. The next image shows how batteries can be arranged in parallel to increase the storage capacity.

Batteries connected in parallel


The batteries should be connected positive to positive and negative to negative using jumper cables. They can be purchased online or in hardware stores. The last positive and negative output in the series must be connected to the inverter to turn the DC voltage into useable AC power. Make sure you source an inverter with a plug adapter output, so you can run an extension cable with a multi-plug adapter away from the system to where you want to use it. Inverters can be quite expensive and will most likely be the most expensive item for this project. But you want a good quality inverter for the safety of yourself and the products you’re using your clean energy to power.

Conclusion

So that’s how to connect batteries to your backyard wind turbine. Now you have all the knowledge and tools to go out and source the best type of batteries for your wind turbine. At the end of the day, it is up to you to decide your budget. So make sure you do your own due diligence before you commit to buying your batteries.

Then it is as simple as connecting your batteries to the generator of your turbine through a charge controller. Then you’ll be able to collect the energy your wind turbine is producing. We’ll cover this in another post here.

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