Lithium-iron-phosphate batteries have been proving their advantages in practice for several years now. They are not only 3 times lighter than their lead counterparts and do not require maintenance. Even compared to other types of Li-ion cells, lithium iron phosphate batteries are a cut above the rest.
They are distinguished by high chemical and thermal stability, excellent fire and explosion safety, frost resistance and a long service life – over 2000 charge-discharge cycles even under harsh operating conditions.
Therefore, LiFePO4 lithium-ion batteries are considered the best choice for installation on all kinds of personal electric vehicles, warehouse and cleaning equipment, wheelchairs, golf carts, electric motor boats, boats, yachts, solar power systems, UPS. LiFePO4 battery show endurance and reliability even in the harsh conditions of daily use.
Tests For LiFePo4 Batteries
But when buying, it is important to make sure that the purchased batteries or batteries correspond to the declared characteristics. To do this, a LiFePO4 test is carried out using measuring instruments and a special load stand. Quality control of lithium-iron-phosphate batteries during their pre-sale inspection includes:
- Visual inspection for visible damage, blisters and other defects.
- Measurement of internal resistance and comparison of the obtained value with the declared technical characteristics.
- Standard test at 1A.
- Testing under a load close to the declared maximum for the tested battery.
- Determination of capacitive characteristics.
Capacity Control Of LiFePO4 Batteries
Measuring the actual capacity of the purchased LiFePO4 cells allows you to find out if it corresponds to the value indicated by the manufacturer, and to assess the suitability of the batteries for subsequent use. When determining the capacity of LFP batteries, despite their tolerance for overheating, overcharging and limiting discharge, it is important to follow safety rules:
- Avoid charging voltage higher than 3.65V and discharge value lower than 2.5V;
- Charge strictly at positive temperature;
- Apply charging and discharging currents that do not exceed the limit values declared by the manufacturer;
- During charging and test discharging, monitor the temperature of the battery cells;
- In case of overheating – the cell temperature rises above 50 °C – stop the charging/discharging process;
- Do not close the contacts of the element without load;
- In the case of using non-automatic chargers, ensure constant monitoring of the process.
To measure the actual capacity of a battery, the easiest way is to use a special device that can properly charge and discharge batteries, monitor their temperature, voltage, charge duration and prevent critical operating modes. In the absence of such a device, you can use a multimeter and a load that consumes a current of 1-2 A.
Capacitance Measurement Algorithm
Let’s describe the algorithm how to check LiFePO4 batteries when buying or in another situation using a multimeter and a load:
- Fully charge the battery cell to 3.2 V.
- Turn on the multimeter in voltage measurement mode and connect it to the battery in parallel.
- Consistently connect a load of 2 A to the element and note the time.
- Discharge the cell until the voltage drops to 2.5 V.
- Multiply the measured discharge time (in hours) by the load current. As a result, we get the approximate value of the actual capacity of the tested LiFePO4 element, in ampere-hours.
In Maxpower company, batteries and batteries assembled from them undergo a thorough quality check, including monitoring at a load stand. Therefore, all batteries of production correspond to the declared characteristics. Maxpower assemble the batteries, strictly follow the assembly technology, carefully check the used elements and finished batteries. At the last stage, the quality of the products is confirmed by the results of the pre-sale check. But you can independently check the characteristics of the battery cells and batteries according to the above algorithm.