The small battery testers you find on battery or battery packaging are an excellent illustration of combining technologies. Many of the technologies that exist are merged in a new manner! The battery testers rely on two distinct kinds of inks which are thermochromic and conductive. Thermochromic ink change colors based on the temperature, and conductive inks can conduct electricity. By putting the inks and an ordinary ink on a typical printing press, it’s possible to produce a cheap printed design that can change in proportion to the amount of power it is exposed to.
There are two kinds of thermochromic inks, Leucodye and liquid. Liquid crystal-based thermochromic ink is extremely sensitive to fluctuations in temperature, but it’s a bit difficult to make. This makes it ideal for applications such as thermometers, where you require the ability to detect temperature changes. However, it is problematic when it comes to items that have to be low-cost and where a huge abrupt temperature change is likely to occur. Leucodyes are specially designed substances that can change from a certain hue, such as blue, to a white state upon temperatures that fluctuate by five to 5 F and above. Thermochromic inks are formulated to change color at specific tem+peratures. In the case of battery testers, the ideal temperature is typically between 100 and 120 degrees F.
For a battery tester, begin by laying down a layer of conductor ink, which becomes thinner as you go from your tester, between “good” and “bad.” The image above shows that the tester is made up of three bars. In other testers, the ink has a wedge shape. The smallest area indicates the charge with the lowest strength; the biggest area is an entire charge. If the current passes over the thin layers of conductive ink, the ink’s resistance creates heat. A small amount will generate enough heat to change the color of the smallest amount of thermochromic ink. However, as the ink’s area expands, the area gets larger, and it will require more current to alter the color.
In the middle of the conductive ink, there is the normal ink that reflects the design. For most battery testers, this will be a “fuel gauge” image or text that tells you that the battery is functioning properly. The design may be anything since an ink-like layer cannot alter how the thermochromic and conductive layers work together.
Then, there’s that thermochromic layer. In the picture of the battery tester, the thermochromic layer turns black when it’s cool. A connection between the negative and positive terminals is formed by rubbing a battery against the ink that is conductive on the back of the paper. When a current is created, and the ink is heated, it becomes transparent. This shows that the design is printed with normal ink. When there’s enough electricity majority or all of the thermochromic inks will reach the temperature required to turn transparent.
One question you may have now is, “Doesn’t test the batteries draw some of the battery’s power?” The answer is “yes; however, it’s not enough to make a difference.” If you test the battery every five minutes, there could be a problem; however, most people do not.
A particular type of battery tester currently available has a tester directly on the battery. Pressing two dots on the bottom of the battery for testing is easy; these dots complete the circuit connecting the battery to the tester. Then, electricity can flow through the ink in the same manner as it does in the tester mentioned previously.
Impedance Battery Testing
This test is non-invasive and intended to establish the performance history of every battery cell. The test is usually conducted annually since it permits performance measurement over time. This allows you to spot any indications of wear or damage or cells with an excessive internal impedance, which could require replacement.
Impedance testing is conducting the AC electrical current through each of the batteries with probes connected to the block terminals. The measured impedance is measured in milliohms.
It provides a general overview of the battery’s condition without putting the batteries under stress or having to take them off.
Another non-invasive test analyzes data from batteries with algorithms used for typical battery conditions, like electrolyte dry-out and sulphation.
Traditionally the tests were conducted in laboratory facilities to determine the likelihood of battery failure on spacecraft and satellites. Today, these tests can be performed with portable handheld devices.
The procedure employs probes at the terminals to measure the frequency response of the current and voltage signals pumped through the battery. The results are compared to performance information for “healthy” batteries.
Since electrochemical testing can measure dry-out of electrolytes and sulphation and not just impedance, it is believed to give an in-depth report of the battery’s state. Blocks that are failing can get recharged with a faster rate to lessen sulphation or completely replaced.
Load Bank Testing (Discharge Testing)
It is the complete battery test and the only real test that determines the battery string’s true capacity.
Tests on the load bank audit the batteries under the normal and peak load conditions. This shows which cells have the charge and which are nearing the final phase of life.
It is recommended that the Institute of Electrical and Electronics Engineers (IEEE) recommends conducting discharge tests before installation and then conducting the test each year.
The major drawback to load bank tests is that UPS batteries need to be removed from operation during the test. The batteries usually are operational for use within 24 hours; however, in the worst-case scenario, they could last for a few days.
Partial Discharge Battery Testing
The name suggests that it is an alternative. Partial discharge testing involves charging the batteries to a maximum of per cent. When they are taken off the market, similar to the load bank test, they will be back in action within 8 hours.
If there’s an issue which requires the UPS to be powered by its batteries, it’s possible to do this, though they’ll only be able to use only 20% capacity.
UPS Battery Monitoring
Alongside battery testing, Monitoring systems for battery performance also monitor the performance of UPS batteries. It is suggested that to use monitoring systems that incorporate the specifications of the widely-known IEEE 1491 standard, including:
String and cell floating voltage
Changes in string and cell voltage and discharge voltage
AC ripple voltage
AC ripple current
The charge for the string is current
String discharge current
Ambient temperature and cell temperature
Internal resistance to cells