How do you extend the life of your battery? Take care of comprehensive diagnostics
The increasing use of batteries as main or emergency power sources increases the need to ensure their safety and optimum performance. How to properly diagnose and maintain batteries to minimise the risks associated with their operation and extend their life?
Versatility and use of batteries
Batteries, or rechargeable batteries, are used not only as energy sources for electronic devices or power tools but also in emergency power systems, internal combustion engines, electric cars, and forklift trucks.
The development of renewable energy technologies such as solar and wind technologies brought about the need for efficient energy storage in energy systems. This makes batteries an increasingly important element of the electricity supply. Their importance as an energy source keeps increasing, both for electromobility and for the stability of electrical grids.
Threats associated with the use of batteries
Batteries, despite their versatility and benefits, can pose some threats. One common problem is the risk of a battery fire or explosion. Overexposure to high temperatures, mechanical damage, manufacturing defects or incorrect charging can lead to uncontrolled temperature rise and related problems.
Another problem associated with the use of batteries is their limited life and capacity degradation due to charge and discharge cycles. Despite the technological advancements, and the development of new types of batteries, the problem of batteries losing capacity still exists. This requires monitoring the performance of the battery and its eventual replacement.
Proper recycling and disposal of damaged and degraded batteries is also a significant challenge. Due to the presence of such substances as lithium, lead or sulphuric acid, improperly disposed batteries can pose a threat to the environment. Proper recycling procedures are essential to minimise the impact of used batteries on the environment and public health.
Types of batteries - a comparison
There are many different types of batteries, each with its own characteristics, purpose and problems. Among the most popular are lead-acid, lithium-ion (Li-Ion) and lithium iron phosphate (LiFePO4) batteries.
Lead-acid batteries are heavier and take up more space – while having the same capacity – than Li-Ion and lithium iron phosphate (LiFePO4) batteries. Moreover, lead-acid batteries tend to self-discharge more quickly and have a lower life-cycle durability than Li-Ion and LiFePO4 batteries.
Lead-acid batteries are simpler and cheaper to manufacture. They can deliver high starting current. Lithium iron phosphate batteries, on the other hand, are more resistant to deep discharges and Li-Ion batteries have the best electrical efficiency.
It should be borne in mind that in order to select a battery well, it is necessary to correctly define your needs such as the intended use and operating conditions, and then choose the right equipment based on the manufacturer's data.
Battery diagnostic methods
All batteries, regardless of their type, have one thing in common: a specific, limited life expressed by the number of charge and discharge cycles. How can you be sure that the battery you have in your car or home energy bank is safe and efficient? When should a battery be replaced?
Assessing the condition of a battery requires diagnostic tests that provide a comprehensive analysis of its condition and performance. Such tests include:
- visual test,
- current and voltage measuring,
- pulsed voltage measuring,
- verification of power supply parameters,
- capacity testing,
- internal resistance tests.
The visual test is a basic but very important part of assessing the condition of a battery. It consists of a thorough inspection of the external surface of the battery to detect visible damage, such as cracks, electrolyte leaks, corrosion on terminals, deformation of the casing or signs of overheating. This process does not require sophisticated equipment, but it does require knowledge and experience to correctly assess the condition of the battery based on the visible symptoms.
Another diagnostic test is voltage verification. This measurement provides information about the condition of the battery's charge. It is particularly important that batteries have the correct nominal voltage level prior to capacity and internal impedance tests. The resting voltage is measured when there is no load, which means that the battery is not connected to any energy-consuming device or system at the time of measurement.
Besides the resting voltage, an important parameter to measure is the pulsed voltage, which is the alternating voltage (AC) superimposed on the direct voltage (DC). Pulsed voltage can originate from several sources. One major source may be insufficient filtering in charging systems, where unsmoothed currents from chargers or converters can lead to voltage fluctuations – so it is very important to verify the battery's charging parameters.
A key step in assessing the performance of a battery is a capacity test. This process starts with fully charging the battery using a suitable rectifier/power supply system – verification of the battery's power supply parameters is also very important. It is important to verify that the current and voltage parameters of the charging system are in agreement with the power supply requirements – as specified by the battery manufacturer.
Photograph 1. Battery diagnostics using a Sonel BT-120 tester
Test your battery with the Sonel BT-120 tester
Measuring equipment capable of accurately measuring voltage, current and time is used to carry out a capacity test. The Sonel BT-120 battery tester is one such device. The procedure starts with fully charging the battery and then discharging it using a controlled load. The load most commonly used for this type of test is resistive in nature, but other external loads of inductive or capacitive nature can also be used, depending on the test specification.
During the test, the device records voltage, current and time data, producing a charge and/or discharge curve. Analysis of the curves in comparison to the original curve provides information about the battery's efficiency at different stages of its duty cycle. This data is used to determine the actual capacity of the battery, which is compared to the manufacturer's rating. Results below 80% of the rated capacity indicate significant degradation of the battery, suggesting the need to replace it.
Photograph 2. Battery diagnostics using a Sonel BT-120 tester
Measurement of internal impedance of the battery
An important element in diagnosing the technical condition of a battery is the measurement of its internal impedance. If it is performed regularly, it can indicate the condition of the battery as it allows to assess its ability to supply energy. Internal impedance refers to the resistance that a battery places on the flow of current within it. High impedance can be indicative of such issues as sulfation, electrode degradation or electrolyte problems.
Internal impedance is usually measured using a four-point method (the so-called Kelvin method). The Sonel BT-120 battery tester measures the internal impedance of batteries by generating and introducing an alternating current (AC) signal at a frequency of 1 kHz ± 30 Hz into the tested battery. This frequency is for one thing high enough to minimise the influence of the DC components of the resistance, and for another to detect changes in impedance caused by battery degradation. It is worth considering that an increase in impedance, for example in energy storage systems, can be caused by a deterioration in the resistance of the inter-block (inter-cell) connections, rather than a reduction in battery capacity. It is thus important to verify the value of the inter-block connection resistance when an increase in internal impedance is detected.
Photograph 3. Battery diagnostics using a Sonel BT-120 tester
Summary
Comprehensive battery diagnostics is based on a variety of protective measurements. Visual tests, capacity assessment, measurements of internal resistance, pulsed voltage, current and voltage, and verification of power supply parameters are all essential to check the condition and operational safety of devices. By regularly performing these measurements, it is possible to detect potential problems such as material degradation or operating instabilities at an early stage, which helps to ensure optimal battery performance.
Photograph 4. Battery diagnostics using a Sonel BT-120 tester
Author:
Michał Cichoń
Product Manager Sonel S.A.
