Dec 03, 2019 Pageview：62
18650 battery is the first lithium ion battery - a standard lithium ion battery model set by Japanese SONY in order to save costs. 18 means 18mm in diameter, 65 means 65mm in length, and 0 means cylindrical battery. Common 18650 lithium batteries include lithium ternary battery and lithium iron phosphate battery.
18650 lithium battery is also divided into capacity type and multiplier type. Capacity type mainly reflects large capacity, but the discharge current is generally lower than 1C, the current is small; The multiplier type can discharge at large current, but have low capacity and short service time.
Due to the fixed size of 18650 lithium battery, its maximum capacity has been concerned by many practitioners. In recent years, various manufacturers have improved their technology and capacity accordingly. Samsung, Panasonic, LG, SONY and Toshiba can achieve more than 3600mAh.
At present, the capacity of good 18650 lithium battery in the market is between 2200 and 3500mAh, and the 18650 lithium battery in this range has the best stability and consistency.
You'd better not use the highest capacity cell to make battery pack, regardless of the cost performance and the service life of the battery pack is not very cost-effective, because the larger the capacity of the battery, the worse its stability, consistency and security are, and the price is also higher. We should choose the right battery according to our product positioning, power consumption parameters (working voltage, working current, working time, etc.) and budget.
|Discharge current||Maximum continuous 4.87A||Maximum continuous 10A||10A maximum continuous current|
Large capacity 18650 battery is assembled by 18650 cells connected in series and parallel to meet the requirements of high voltage and high capacity of different devices. The more cells connected in parallel, the larger the capacity of the assembled battery is.
18650 battery connected in parallel: With constant voltage, battery capacity increases, internal resistance reduces, and power supply time is longer.
18650 battery connected in series: voltage increases but capacity is unchanged.
Therefore, there is no definite capacity for the largest 18650 battery. Different battery manufacturers can produce 18650 batteries with different capacities according to requirements. Dongguan Large Electronics Co., Ltd. can customize 18650 lithium batteries with super large capacity according to customer requirements.
10.8V 537Ah Large Capacity 18650 lithium ion battery Pack
Product number: 32AQ009-01
Battery weight: 35Kg
Product dimension: 480×280×200mm（Max）
Discharging temperature: -20～60℃
Temperature protection: 65℃±5℃
Protection function: short circuit protection, overcharge protection, over-discharge protection, overcurrent protection and temperature protection
Shock-resistant and waterproof: fill in the shock-resistant structure inside the cold pressing metal plate housing to satisfy the requirements of good security and high reliability.
Super large capacity: apply imported 18650/3.7V/3350mAh battery cell with large capacity and density, which has small volume.
Reliable connection: adopt GJB aviation connector, which is safe and reliable.
Communication protocol: have RS485 communication protocol and can read the information of battery capacity, temperature, power source, current, etc.
Safety management of the battery: when the temperature probe of battery finds out over temperature status, the protection system is on automatically.
The battery pack has long cycle life, which conforms to the principle of low carbon, energy conservation and environmental protection.
The discharge characteristics of 18650 battery determine the battery used in different application fields. According to the discharge characteristics of 18650 battery, 18650 battery can be divided into capacity battery and power battery. The discharge curves of these two kinds of 18650 battery are different under different conditions. Here take two types of Panasonic cells for example to know more about the difference of discharge curve between capacity cell and power cell.
Capacity Cell （Panasonic UR18650ZTA）
Cell model：Panasonic UR18650ZTA（High Capacity Models）
Minimum capacity: 2900mAh
Discharging temperature: -20-60℃
Panasonic UR18650ZTA Discharge Curve at Different Rates
As you can see from the discharge curve, when the discharge voltage reaches 3.0V, the capacity of this 18650 battery is about 2900mAh. When the discharge current is 0.2c, the capacity is about 2300mAh. When the discharge current is 2C, which does not reach the standard range of the battery, it shows that this 18650 cell is not suitable for high rate discharge.
Therefore, the capacity cell should be a battery with high capacity but small current discharge for a long time, which is suitable for medical equipment, power equipment, instruments, consumer batteries, outdoor equipment, etc.
Power Cell（Panasonic UR18650RX）
Cell model：Panasonic UR18650RX（High Drain Models）
Minimum capacity: 2050mAh
Discharging temperature: -20-60℃
Panasonic UR18650RX Discharge Chart
The capacity of lithium battery is the premise of equipment working hours. There is a certain deviation between the labeled capacity and the actual capacity of general manufacturers, which is the so-called fake standard of battery capacity. How do you measure lithium battery capacity accurately? Let's talk about the 18650 lithium battery capacity measurement methods.
You can find an adjustable load resistance and a DC power supply with adjustable current to calculate the battery capacity by charging and discharging time. Through the battery capacity calculation formula, you can deduce the capacity of 18650 lithium battery:
Charging test: charging current × charging time = battery capacity (from 2.7V or 3.0V to 4.2V);
Discharge test: discharge current × discharge time = battery capacity (discharge from 4.2V to 2.7V or 3.0V).
Fully charge the battery to reach the rated voltage, which is generally 4.2V;
Discharge the battery to the rated voltage, and record how much electricity is released, and the voltage is generally 3.0V;
Charge the battery to the normal capacity, which normally sets at 3.8v-4.0V;
The capacity recorded in the second step is the battery capacity.
The 18650 battery tester is an instrument to test the battery capacity by setting charging and discharging parameters. The specific functions are as follows:
1. Check Discharge Test
Discharge current can be continuously set. According to the setting discharge current with constant discharge, monitor the battery pack and cell voltage during discharge, and measure the capacity per battery pack (check capacity test).
2. Quick Measurement
According to the short-term discharge of the battery, 18650 battery tester can quickly test the internal resistance and discharge capacity of cell, and quickly check the performance of the battery.
3. Online Load Discharge Test of Battery Pack Capacity After Power Failure
During power failure/actual load discharge, the cell voltage, battery pack voltage and discharge current are automatically monitored online, and the discharge capacity of 18650 battery is recorded to ensure the judgment of the state of 18650 battery.
4. Data Management
Good analysis monitoring software of the computer management has powerful data processing function, uses the advanced mathematical model of multiple measurements of 18650 battery based on the analysis of calculation, checks the battery performance precisely, and can query 18650 battery real-time running status and historical data, including the various parameters, curves, and generate reports.
5. It can test the performance of 18650 battery, so as to identify the cell with high performance.
At present, there are a large number of 18650 battery distributors and manufacturers in China, whose products vary greatly in price and quality. It is difficult to identify 18650 battery without excellent performance detection instrument.
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