In our previous post we have been examining the application of NiMH (Nickel Metal Hydride) batteries in solar lighting systems. Such an examination would not be complete without having considered the application of Lithium-ion batteries in solar lighting.

 

Both, NiMH and Lithium-ion batteries represent the most popular types of batteries used in LED solar lighting systems and undoubtedly there is a recent trend of Lithium-ion batteries becoming more popular. The main reason is the extended lifespan of Lithium-ion batteries whcih is closely connected to the cycle life of a battery.
 

 

The cycle life describes the number of charge and discharge cycles that a battery can complete before losing performance and can have different ranges from as much as 500 to 2500 cycles or 18 months to 3 years. The cycle life is affected by several factors, including the depth of discharge (mAh), time, battery material and temperature. Dragonfly Energy lithium-ion batteries can have expected life cycle ratings between 3,000-5,000 cycles , outperforming NiMH batteries by far.

 

Obvioulsly the main reason of this long lifespan of Lithium-ion batteries is their higher density, making them superior to NiMH batteries and by far superior. Needless to say that his higher density comes at a cost. Lithium-ion batteries are the most expensive ones amongst others due to lithium-ion cathodes being made of the expensive material cobalt.

 

Interestingly both, NiMH and Lithium-ion batteries require a specific charging mechanism to prevent over-charging and over-discharging which their common disadvantage compared to other batteries.