NICD NOT A PRIME CHOICE FOR SOLAR LIGHTS
NiCd (Nickel Cadmium) batteries are not one of the best solar battery choices on the market for use in solar energy lights. There’s a debate in the “battery community” about what’s called the “memory effect” with NiCd–these kinds of batteries are meant to be charged fully and depleted fully.
That isn’t what happens often with batteries meant for solar lights, where there’s a constant charge-discharge with the cycles of day and night. The memory effect alters the battery’s voltage levels to shrink over time, where the battery “forgets” the highs and lows it doesn’t often charge to. Typically, the best battery for solar lights (with a properly-sized system) will discharge about 15% every day.
Plus, cadmium is a highly toxic metal which defeats one of the purposes of solar lights–to reduce the environmental impact that the use of energy may have. Many NiCd batteries even have “POISON” stamped across the top. We know most project managers just prefer something that saves money over time, but why not go both routes of cost-effective and environmentally safe?
NIMH CLOSER, BUT STILL NO CIGAR
NiMH (Nickel Metal-Hydride) technology is a better choice over NiCd batteries when it comes to the environment, but there are still some pain points with this selection. There’s a lot of maintenance required with NiMH batteries because they need a full discharge from time to time–we’re sure someone doesn’t want to get the task of discharging every battery in a solar parking lot light configuration.
The best application for these batteries are for small electronics like flashlights and toys since they operate best with high energy consumption and demand instead of small, cyclical power drains or low-energy applications. Still not the best battery solution for solar street lights.
lead-acid battery plate composed of lead and lead oxide, electrolyte for sulfuric acid aqueous solution. Its main advantages are voltage stability and low price. The disadvantage is that the specific energy is low, resulting in a relatively large volume and short service life, about 300-500 deep cycles, requiring frequent routine maintenance. The battery is still widely used in the solar street lamp industry.
Colloidal battery（gel battery）
In fact, lead-acid battery is an upgrade of the maintenance free version, through the colloidal electrolyte instead of sulfuric acid electrolyte, in terms of safety, storage, discharge performance and service life than ordinary batteries have been improved, the price of some even higher than three lithium batteries. It can be used in the temperature range of -40℃ to -65℃, especially good performance at low temperature, suitable for the northern alpine region. Strong seismic performance, can be used safely in harsh environments. The service life is about twice as long as the ordinary lead-acid battery。
Ternary lithium battery
higher than the energy, small size, fast charging, but the price is higher. The number of deep cycles is about 500-800 times, the life of the battery is about 1 times longer than that of the lead-acid battery, and the temperature range is -15℃ to 45℃. However, less stable, unqualified manufacturers of ternary lithium batteries may explode or catch fire when overcharged or too high temperature.
lithium iron phosphate battery(LifePO4 battery)
Hgher than the energy, small size, fast charging, long service life, good stability, the price is the highest. The number of deep cycle charging is about 1500-2000 times, long service life, generally up to 8-10 years, strong stability, wide temperature range, can be used in -40℃ to 70℃.
To sum up, solar street lights of course use lithium iron phosphate batteries best, although the price is higher. At present, the market solar street lamp using lithium iron phosphate battery price is very reasonable product, the life of this product can reach 10 years, the price is also very attractive.
Luxman’s solar street lights are all powered by lithium iron phosphate batteries.