YDSL solar street light manufacturer, supplier in China

Solar light batteries:
Li-ion cell battery or LiFePo4 cell battery?

In the industry of solar light batteries, selecting proper batteries is important for guaranteeing long-term and effective energy lighting. YDSL will perform a full comparison of lithium-ion (18650) and lithium iron phosphate (32650) batteries to find out which is the best option for solar lighting applications.

What are 18650 and 32650?

It is easy to understand how to name cells by dividing numbers into three parts, as shown in the below photo:
There are four numbers that tell us about the solar light battery’s model. The first two numbers tell us about its width. The third and fourth numbers tell us about its height.
Based on what was said above, it is clear that the 18650 li ion battery cell is round, measuring 18 mm across and 65 mm tall. The base of the LiFePo4 cells are 32 mm wide and 65 mm tall. The picture on the right shows how the sizes of the graphics in two different cells compare.

solar light batteries with different type
teach people how to know the battery type

Features of 18650 Li ion battery

The rechargeable lithium battery has a voltage of 3.7 V and an energy density of 150–220 Wh/kg. The energy efficiency of these batteries is higher than that of LiFePo4 batteries.

Many major electric vehicle manufacturers use Li ion batteries, including BMW i8, Audi e-Tron, These are also used for small solar light batteries, such as lawn lights and post lights.

feature of liFePo4 32650 Battery

A lot of people like lithium iron phosphate (LiFePo4) batteries, because they last a long time, don’t get damaged by heat, and don’t self-discharge quickly. It’s important to note that batteries (LiFePo4) have a low voltage of 3.2V and a low energy density of 90–160 Wh/kg. But because they are cheaper, last longer, and release quickly, when making battery packs for energy storage systems, solar light batteries, like high power solar street lamps, green energy flood lights, or even electric cars, are the best choice. Tesla just recently said that their new Model 3 will use 32650 LiFePo4 cells.

Advantages of 3.7v li ion battery over 3.2v LiFePo4 battery

Larger energy density: If the energy density is higher, Li-ion 3.7v batteries will be smaller and lighter for packs with the same amount of power.
Single batteries that look smaller:
Due to its smaller size, the rechargeable li ion battery works better in situations that need very little power, like garden lights solar, fans, ceiling lights, and decorative lights in the sun.
Less expensive:
The lithium-ion battery 18650 is less expensive than LiFePo4 batteries for the same amount of power. This means that the Li-ion battery can be used for outdoor or indoor, economical solar lighting applications.
The higher beginning voltage: The rechargeable li-ion battery has 3.7 volts of power, while the LiFePo4 solar battery has 3.2 volts. A higher standard voltage means that fewer batteries linked in series are needed to make higher voltage battery packs. This makes the system smaller, cheaper, and easier to produce, like solar lanterns, which do not have enough space to equip solar light batteries
In other words, we want to make a 50V battery pack. 18650 li-ion battery and 32650 cell LiFePo4 both need at least 14 and 16 battery cells connected in series.

Advantages of solar light batteries LiFePo4 over Li-ion battery

More secure: Because they don’t change as much when they get hot as lithium ion batteries do. At temperatures between 280 ° C and 150 ° C, LiFePo4 batteries enter a thermal runaway state, which is almost twice as high as what 3.7 v  batteries need. During this time, LiFePo4 cells release less than three quarters of the energy that 3.7 batteries do. Because of this, the 32650 battery is a lot safer than the 18650 battery in solar light batteries. There are too many cases of lithium ion solar light battery explosions in high-temperature areas.

Longer life span: LIFePo4 cells last a far longer time. LiFePo4 solar batteries can be charged over 2500 times before they lose 80% of their original power, while Li-ion batteries need only 1000 charging cycles. Overall, this also means that LiFePo4 batteries will be cheaper to run over time and be better for long-term uses.

Higher discharge current: LIFePo4 cells can offer a discharge current of 1C, and some batteries can offer a discharge current of more than 10C. The 18650 li ion battery, on the other hand, can only offer a discharge current of 1-2C. The 18650 and 32650 batteries, on the other hand, have different amounts of capacity. At the same 1C discharge rate, the 32650 LiFePo4 cells will offer two to three times the discharge current of the 18650 life battery. At the end of the piece, there is an answer.
The 32650 battery is better for tasks that need more current, like high-power solar street light batteries for roads, high-lumen solar flood lights for stadiums, or powering big industrial equipment, because it has a higher discharge rate from solar light batteries.

Additional knowledge extensions

1. C represents the capacity of the battery itself, in AH/MAH units;

2. C: Used to represent the ratio of the charging and discharging currents of a battery, that is, the multiplier.

In other words, the battery capacity is 1000 MAH, and 1C discharge is 1000 MAH discharge.

The size of the general charging and discharging current is commonly represented by the charging and discharging ratio, which is: charging and discharging ratio is equal to charging and discharging current/rated capacity. For example, when a battery with a rated capacity of 100Ah is discharged at 20A, its discharge rate is 0.2C. The discharge rate of a battery, 1C, 2C, 0.2C, is a measure of the speed of discharge.

What are the differences between 18650 and liFePo4 Cell ?

Li-ion Battery LiFePo4 Battery
Standard Voltage 3.7V 3.2V
Operating Rang Voltage 3-4.2V 2.5-3.7
Capcity 150-220 Wh/Kg 90-120 Wh/Kg
Cycle Life 1000-1500 2500-3500
Thermal Runaway 150° 270°

Volume comparison:

The volume of a battery is an important parameter, as its capacity depends on the size of the electrodes. Therefore, volume directly affects the purpose of solar light batteries. The volume of cells is given by the following equation:

V=π r ² H
Volume of 18650 = 52.28 cm2
Volume of 32650 = 209.1 cm2
From the above data, it is clear that the volume of 32650 LiFePo4 cell batteries is almost four times that of 18650 batteries, so the energy of Life batteries should be about four times that of 18650 batteries.

Comparison capacity:

The capacity of lithium-ion batteries is measured in mAh. The capacity of a battery determines its battery life. Batteries with higher capacity have a longer duration than batteries with lower capacity. The capacity of a battery depends on the size of the electrode material. Therefore, larger batteries will have a higher capacity.

Therefore, the capacity of the lifepo4 cell battery is higher than that of the 18650 li ion battery, so it can last longer than the 3.7 voltage battery 18650 in similar green energy lighting applications.

Application campare:

The types of solar light batteries you choose depend on a number of things, like how much power and current the solar light needs. Based on what was said above, it’s clear that the 18650 is smaller and has less space, which makes it more compact. The bad thing is that its capacity and charging rate are smaller than those of similar 32650 batteries. 

Because of this, 18650 batteries are better for low-power uses like small electronics that run integrated systems or have lower current needs. In situations where a lot of power is needed, like electric tools and high-power flashlights that need a lot of current, LiFePo4 battery cells are better. The 32650 battery also works better than the other one.

different points compasion with two batteries

Conculison

It’s not fair to compare 3.7v li ion battery and 3.2v LiFePo4 deep cycle lithium batteries, but the fact that they can be used together is a key factor in selecting. Even though 18650 batteries are less expensive than 32650 batteries, they can’t be used in situations where the battery needs to last longer. The 18650 li ion battery is better for low-power uses because of its size and energy efficiency. It lasts for two to three years. There is no reason to think that 18650 lithium-ion batteries are better just because they sell more than 32650 lithium-ion batteries. When compared to 18650 batteries that have the same chemical makeup, 32650 batteries usually have more energy and drain faster, which makes them better for devices that use a lot of energy, like hig power solar light batteries.

 

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