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What size solar battery maintainer do I need?

Solar battery maintainers also known as solar battery tenders are essential part of a solar lighting system. They help maintain the charging speed of the battery, shuts off the charging process when the battery is full, and converts solar energy into electricity. 

When buying a solar battery maintainers, you will have to consider the size of the maintainers, and the voltage of your batteries. So how would you choose the right size of solar battery maintainer for your solar battery?

Size of the maintainers might be classified into amps, the actual physical size, and the watts produced by the batter. In this post, we will outline all the factors that affect the size you choose for your battery. We will also tell you the benefits of having a solar battery maintainers on your solar lighting system.

What size solar battery maintainer do I need?

You might be wondering why the size of the maintainers matter and if having solar batteries matter on the solar lighting system. The thing is that, solar lights are supposed to make our life easier. To achieve that, you will need to take good care of your battery. 

A properly maintained battery will last longer and offer a large power holding capacity. Solar battery maintainers will maintain the speed of battery charging and shut down current when the battery is fully charged. So what does size have to do will that?

If you are using a small solar panel , then you will need a smaller solar battery maintainer of about 5×5×1 inches and produce about 5watts. You might also be lighting a large compound with many solar lights and batteries. There you will have to get large solar maintainer of size 9×8×6 inches. 

There are people who use solar lighting for their boats and motorcycle. In that case you will need a tiny solar maintainer due to transportation. Standard size for  small solar battery maintainer is approximately 6×4×2 inches. While medium solar battery tenders are approximately 8×6×3.5 inches and a large battery maintainer are approximately  9×8×6 inches. 

 Those are just few examples of what factors you might consider  when choosing solar batteries of a particular size. Below, we will discuss the factors that determine the size of the battery. 

How do you size a battery maintainer?

There are a number of factors that you will consider when sizing a battery maintainer. This video will give you an introduction on how you size a maintainer as we continue discussing more  about battery maintainers.

Physical size

 The actual size of the solar batteries affect what solar battery maintainers you will buy. Solar battery maintainers physical size vary. You will find a smaller battery maintainer which is approximately 8×10 inches, and 26×11 inches for a large solar battery maintainer.

Determine the size of the solar panel you are going to use with the battery maintainer and portability issue when choosing a solar battery maintainer.

Wattage produced. 

The amount of wattage produced affect the amount of charge entering the solar battery. There are three types of solar battery maintainers when classified with the size of wattage produced. 

  • Low wattage: These solar battery maintainers produce about 1.8-5 watts of power. They cannot charge large solar batteries. They are slow but also affordable. 
  • Medium wattage: These solar battery maintainers produce about 7.5- 10 watts of power. They can charge many types and batteries different sizes.
  • High wattage: These maintainers produces around 18-20 watts of power. They are specifically designed for large and powerful batteries. They are the most expensive solar battery maintainers.

How many amp battery Maintainer do I need?

Solar battery Maintainers help maintain the charge in the battery. The battery voltage will determine how many watts your solar battery maintainer should have. The amount of Amps solar battery maintainer can have include:

  • Battery maintainer 1.25 Amps: A 1.25 Amps solar battery cannot charge powerful solar batteries. They are ideal for  maintaining the charge of the battery. They can however charge a battery with low voltage. Battery maintainers with 1.25 watts measure about 9×4×11 inches.
  • Battery tender 4 Amps: Solar batteries with 4 Amps can charge 6-12V batteries. It is the only battery tender compatible with large range of batteries. This battery can revive a flat battery. They measure about 6.9×3.33×1.91 inches.
  • Solar battery maintainer 5 Amps: These battery maintainers with 5Amps are ideal for powerful solar batteries with 12V. This battery maintainers measure 8.2×3.9×2.3 inches.

How many watts does a battery maintainer need?

The number of watts the battery maintainer needs is determined by the size and the voltage your solar battery have to offer. There are three types of watts range produced by the solar battery maintainers as discussed above. This different watts battery maintainers are compatible with this solar batteries.

  • Small solar battery : This batteries do not require large amount of energy to charge. Small batteries can be charged with a solar maintainer producing 1.8-5 watts.
  • Medium solar batteries:  medium batteries which measure 6.9×3.33×1.91 inches are  compatible with solar battery maintainers that produce 7.5-10 watts. 
  • Powerful large solar batteries: For batteries which measure about  8.2×3.9×2.3 inches are efficiently used with solar batteries  that produce 18-20 watts of power.

How big of a solar battery charger do I need?

To find out the size of a solar battery charger you need, measure the power produced by the solar panel and divide by the voltage of your solar battery. For example, a solar panel that produces 1kW of power charging a 12V battery requires a battery charger of 1000/12= 83.33 Amps.

Frequently Asked Questions (FAQs)

Can  solar battery maintainer overcharge a solar battery?

Solar batteries tend to overcharge if the charging process is not controlled. Overcharging a battery is dangerous as it may lead to the battery bulging or even exploding. To prevent over charging, a solar battery maintainer is  connected to the solar panel. A solar battery maintainer shuts down any current trying to reach the battery when it is fully charged.

What is the purpose of load connection on my solar battery maintainer?

Some controllers have a load output for smaller appliances and smaller batteries. The low voltage disconnects of the load connection turns off any appliances connected to the load terminal to prevent the battery from draining fully. 

Is a solar battery maintainer worth it?

Among the most helpful solar devices, solar battery tender is a vital device. Sometimes the energy produced by the sun might be too high and charges the battery faster. Your solar panel might be too powerful and harvest too much power. In those cases, a solar maintainer will be help control the charging process. A solar battery maintainer will shut off any current  from reaching the battery causing the battery to overcharge.

Are solar battery maintainers expensive?

The price of the battery maintainers depends on the quality, size, number of wattage produced and the brand of the maintainers. Generally, solar battery maintainers are affordable. 

A low wattage battery maintainer cost around $20-$30, a medium wattage $50-$80, and a high wattage battery maintainer cost around $100-$120. It is advisable to invest on a high quality battery maintainer for long term services. 


A solar battery maintainer is a vital device every solar lighting system owner should have. They help maintain the battery charge while still boosting the performance of solar battery. 

To ensure the solar battery maintainer work efficiently, learn how to size the battery maintainer. Powerful solar batteries work best with high wattage solar maintainers. Also a 4 Amps solar battery maintainers can charge a 6V and 12V solar battery. A 1.25 Amps solar battery maintainer is not ideal for powerful solar battery.

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