Best AA Rechargeable Batteries For Solar Lights

AA rechargeable batteries are very often used to power small solar lights commonly used in the garden, backyard, along the pathways, and similar.

Rechargeable batteries for solar lights should feature broad charging and discharging temperature range, should support a large number of charging/discharging cycles, should support charging with various currents, must be safe for use, and similar.

Published: December 14, 2022.

AA Battery Chemistries

AA batteries are very popular cylindrical batteries featuring physical dimensions of (D x L) 14.5 x 50.5 mm (0.57 x 1.99 inches).

They also feature a large number of different battery chemistries, with each chemistry being at least slightly different than the other one.

The following comparison chart lists some of the most popular AA battery chemistries, with their most important features and specifications.

As one can see, rechargeable AA batteries include the following chemistries:

• NiCd or Nickel Cadmium batteries,
• NiMH or Nickel Metal Hydride batteries,
• Li-Ion or Lithium-Ion (14500) batteries,
• LiFePO₄ or Lithium Iron Phosphate (IFR14500) batteries,
• NiZn or Nickel Zinc batteries.

Although Lithium and Nickel-Zinc batteries offer various benefits over Nickel Metal Hydride and especially Nickel Cadmium batteries, the most popular AA rechargeable batteries for solar lights are Nickel Metal Hydride batteries, with Nickel Cadmium also being offered.

Note: When replacing your old solar light batteries with new ones, always use batteries of the same chemistry, preferably with the same or slightly larger capacity. But, new batteries should be advertised as solar light batteries since they must withstand both high and low outdoor temperatures.

Nickel Cadmium (NiCd) Solar Light AA Batteries

First of all, NiCd batteries are being phased out in favor of NiMH batteries due to their Cadmium content and the fact that NiMH batteries generally feature larger capacity and support a larger number of charging/discharging cycles. Also, modern NiMH batteries don't suffer from memory effect like NiCd batteries, and they have a lower self-discharge rate.

Having said that, NiCd batteries are reliable (as long as they work) and relatively cheap, and their self-discharge rate is not important for applications where they are being charged and discharged daily.

With their nominal voltage of 1.2V, good NiCd solar light batteries feature a nominal capacity of 800-1100 mAh - they are not required to provide huge currents and as such are offered as high-capacity NiCd batteries.

Nickel Metal Hydride (NiMH) Solar Light AA Batteries

As said before, NiMH batteries offer many benefits over older NiCd batteries.

NiMH batteries feature a nominal voltage of 1.2V and a nominal capacity in the 700-2800 range. However, NiMH solar light AA batteries typically feature a capacity in the 1000-1500 mAh range since they have to be hardened for outdoor use.

If You are tempted to place large-capacity NiMH batteries in your solar lights, especially during long summer days, these batteries will probably be fully recharged in the evening and will power solar lights through the night easily.

However, such batteries will not last for a long time - sometimes a few months, and during periods of really hot weather, they will last a few weeks since the batteries will be simply cooked.

Thus, when looking for NiMH solar light batteries, always go for the models labeled as such.

Note: if You find NiCd batteries in your solar lights, check the documentation, and if supported, replace them with new NiMH batteries. Of course, always recycle old batteries properly, regardless of their chemistry.