There are some kinds of batteries in the market for solar lights: Lead-acid battery, AGM battery, gel cell deep cycle battery, and lithium battery.AGM battery and gel cell deep cycle battery are other types of a lead-acid battery. Let’s see the character of each of them, then we’ll know which one is better for the solar parking lot lights.
Lead-acid battery
Lead-acid batteries have been used for more than 130 years in many applications and they are still the most widely used rechargeable battery for small-medium scale storage applications.
Advantage of lead-acid battery: Low cost; It’s almost fully recyclable; Reliable and tolerant to abuse; it’s available in various shapes and sizes; withstand overcharging; low self-discharge.
The disadvantage of lead-acid battery: Heavy and bulky; not suitable for fast charging; dependence on hazardous and restricted lead, not environmentally friendly; temperatures above 20ºC reduce the lifetime of lead batteries rapidly; limited cycle life, it means short lifetime;
AGM battery
Absorbent glass mat (AGM) battery feature fiberglass mesh between the battery plates which serves to contain the electrolyte and separate the plates has been a market favorite for the past few decades, mainly used in military vehicles as a source of back up power and heavy vehicles such as long-distance trucks.
Advantage of AGM battery: Fast charging, up to 5 times faster charge than with flooded technology; maintenance-free; low self-discharge;spill-proof, because the glass mats holding the electrolyte in place; longer lifespan; durable and could withstand extreme temperature variations.
The disadvantage of AGM battery: Heavy and bulky, low specific energy; high cost; low tolerance to overcharging and high voltages; the capacity has gradual decline.
Gel cell deep cycle battery
The gel cell battery is similar to the AGM battery because the electrolyte is suspended, the difference is AGM battery is a wet cell battery, and the gel cell battery has a silica additive to set up or stiffen electrolyte.
Advantage of gel cell deep cycle battery: Save you from acid leakage and frequent maintenance; corrosion-resistant grids enable long lifespan up to 10 years; low self-discharge; more charge/discharge cycles; last a bit longer in hot weather applications.
The disadvantage of gel cell deep cycle battery: The recharge voltages are lower; sensitive to over-voltage charging; Heavy and bulky, low specific energy.
Lithium battery
Lithium batteries have metallic lithium as an anode. Over the last decade, lithium has been proven to be extremely reliable battery technology. Lithium batteries are widely used in electric cars, cell phones, cameras, laptops, and other mobile devices. Lithium batteries are even used for energy storage in the electrical grid. So it seems like there would be a lot of advantages of lithium batteries over the more traditional types of batteries such as lead-acid batteries.
For solar parking lot lights, the lithium iron phosphate battery (LiFePO4 battery) is commonly used. It’s a type of lithium-ion battery using LiFePO4 as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode
