Solar lights need batteries to store energy transferred from the solar panel. The rechargeable battery charges during the day to power the solar lamp during the night. 

The capacity of a rechargeable battery gradually decreases over time. While a new battery may power an LED bulb for 10 to 12 hours, an older battery may only last for a few hours. The brightness of the light may also decrease.

If your solar lighting system no longer provides illumination throughout the night, you may need to replace the battery. Here is what you should know.

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Why Do Solar Lights Need Batteries?

Why Do Solar Lights Need Batteries?

The battery stores the electricity converted from solar energy provided by the sunlight. A solar light includes a solar panel, which consists of photovoltaic cells (solar cells). The solar cell creates an electrical current when exposed to sunlight.

The electricity passes to a charge controller, which is a small circuit board used to protect from a voltage spike or current spike. The current passes from the controller to the rechargeable battery.

The solar battery slowly charges throughout the day so that it is ready to light the artificial light bulbs throughout the night.

What Types of Solar Light Batteries Are There?

You will not find a lead-acid battery or alkaline battery in your outdoor solar light. Solar lights use rechargeable batteries. The most common types include:

  • Lithium-ion batteries
  • Nickel-cadmium batteries
  • Nickel-metal hydride batteries

Each type of battery has separate pros and cons for your outdoor lighting. 

Lithium-Based Batteries

Lithium-ion batteries are commonly found in devices that require rechargeable batteries. Lithium batteries are available with higher voltages, allowing them to power bigger devices. However, they are not as efficient for low-powered devices, such as solar lighting.

Nickel-Based Batteries

Most solar-powered garden lights have nickel-cadmium (NiCad) or nickel-metal hydride (NiMH) batteries. NiCad batteries became popular in the 1990s, as they do not experience a voltage drop as the battery discharges. 

NiMH was designed as an improvement over the NiCad battery. A NiMH battery offers up to 30% more capacity and recharges easier. These features help NiMH batteries last a little longer compared to NiCad or lithium-ion batteries.

Are They Easy to Replace?

Replacing the solar light battery is quick and simple. The top portion of the typical solar garden light contains the solar panel and the battery compartment. Unscrew the top of the enclosure to reveal the battery compartment door.

Most designs include 18650, AAA, or AA rechargeable batteries. As with disposable batteries, each battery has a positive and negative contact on the ends. You simply remove the old battery and insert the new one.

Can You Replace Nickel Cadmium with Nickel Metal Hydride?

Yes, you can replace a nickel-cadmium battery with a nickel-metal hydride battery. Replacing a NiCad battery with a NiMH battery may help power your lights for a longer duration at night. 

Avoid increasing the capacity too much. A major change in capacity may damage the rechargeable battery and your solar yard light.

Quick Tip: Always choose a battery with the same voltage as the original battery in your outdoor light. The battery capacity should match or exceed the capacity of the original. Most solar lights use 1.2V batteries with a capacity between 200 mAh and 1600 mAh.

Can You Replace Nickel Cadmium with a Lithium-Ion Battery?

Yes, you can technically use a lithium-ion battery. However, lithium-ion batteries degrade faster. They also tend to cost more compared to NiCad and NiMH batteries. 

Can You Use Standard Alkaline Non-Rechargeable Batteries in a Solar Light?

No, you should never place a disposable battery, such as standard AA batteries, in a solar garden light designed to use rechargeable batteries. Regular batteries are not designed for charging.

The solar panel and internal components of the yard light act as a battery charger during the day. Attempting to charge a disposable battery could damage the battery and solar light.

How Long Do Solar Light Batteries Last?

Most solar-powered light batteries should last up to two years. However, you may notice degraded performance after just one year of using your outdoor solar lighting, especially when using NiCad or lithium-ion batteries.

Conclusion

The rechargeable batteries in your garden solar lights will likely need replacement at some point. A solar landscape light requires a rechargeable battery to store energy captured by the photovoltaic cell. As the battery degrades, it holds less of a charge, which limits how long your lights stay on at night.

If your decorative solar lights start to dim earlier at night, try replacing the batteries. Always match the voltage of the new battery to the old one, which is typically 1.2 volts.

Using a NiMH battery may help your lights stay on longer, as NiMH batteries can provide more capacity and less memory leak compared to NiCad batteries.

You may also choose batteries with more capacity, such as replacing a 200 mAh capacity battery with a 300 mAh capacity battery. 

If replacing the battery does not help improve the performance of your solar lights, you may need to clean the solar panels or try placing them in a different position. The batteries may not be charging due to a lack of sunlight.