A UPS backup battery is a commodity with a fixed service life that is further reduced or influenced by many external factors.
There are several things that one can do to ensure that the UPS backup battery is kept in optimal condition and delivers the best battery service life:
- All batteries are susceptible to high temperatures, some battery technologies more than others. For example, lead acid-based products, where temperatures above 25 to 30 degrees C, can halve the service life. Keeping a battery cool at less than 20 degrees C is an effective way of preserving its service life. An effective demonstration of this is the high-end car manufacturers that place the battery anywhere but in the engine compartment. This is done to prevent the negative impact of the massive heat in the engine compartment on the battery and thereby increase battery service life.
- All “sealed” type technologies, which is the normal type of battery used in a UPS system for emergency backup power, are equipped with a valve to protect them should the battery ‘gas’ under abnormal charging conditions. Instead of the battery pressure getting so high that the battery bursts, the valve will release small amounts of gas to stop this. During “sealed” battery operation, there is a condition known as recombination efficiency, whereby a very small amount of gas created during charging or discharging the battery will never recombine back into the battery electrolyte (Acid solution). This gas that never recombines will periodically need to be purged to prevent the battery from exploding. Therefore, it is important to ensure that your batteries are kept clean and dust-free and that the valve doesn’t get blocked.
- Depth of discharge is also a very important factor when sizing a battery. The more power you take out of a battery, the deeper the discharge, especially long slow discharges of more than 30 minutes. Long discharges of hours use up all the available energy in the battery, while short quick discharges only use up a small amount of the total available energy. This is because a battery is a chemical process, so during a high rate discharge of up to 30 minutes, the chemical reaction on the plates is limited. This hinders the battery power delivery due to the chemical efficiency being poor. The opposite occurs on long slow discharges where the chemical efficiency is of no consequence. If a battery is required to do a long discharge of hours, it is important to ensure it will recharge to 100% capacity before the next discharge. Therefore, after a 4-hour discharge, under rolling blackouts, it is important not to take out so much capacity that the battery will not be fully charged before the next discharge. Normal UPS applications are sized for float applications, i.e., a discharge once a month, maybe. In this case, batteries need about 72 hours to be fully charged – also called top of charge or TOC. Therefore, in battery sizing, the depth of discharge, i.e., the amount of capacity you remove during a discharge, must be factored in if the application is more frequent discharges than a float application, also called cyclic application.
- UPS battery charge and discharge settings are very important as the type of backup application will determine the battery manufacturer’s requirement for charging the battery after a discharge. Under cyclic battery discharge applications, the charging current and voltage settings on the rectifier are much higher than under a float charge application. This is to ensure the battery gets to TOC as fast as possible. But at higher recharge settings, the battery service life is drastically decreased.
- UPS rectifier available recharge current is another very important factor when choosing a UPS. Not all UPS systems have big battery chargers. A high-quality Riello UPS from Italy will ensure the user of an effective battery recharge current. Otherwise, the battery will never get fully charged in time for the next discharge under cyclic conditions.
- UPS rectifier quality and build are also very important as a good quality UPS like Riello will provide clean and pure DC power to the battery due to its high performance, high-end, and, therefore, more costly rectifier. Poor quality rectifiers deliver DC power to the battery that is full of electrical “noise”. This “noise” damages the battery internally over time, causing premature failure of the battery.
- A high-quality and in-depth Battery care system, like that offered with Riello UPS units, is another excellent way of ensuring the maximum service life out of a battery. This may include a battery monitoring system or BMS that is usually external to the UPS unit, but only economical to consider with very large battery banks worth hundreds of thousands of Rand as a decent BMS is very expensive. Don’t be caught by a cheap BMS system; you are wasting your money. A decent BMS must measure block voltage, current, temperature, and impedance as well as have a detailed event history with discharge curves and data.
Elite Batteries are the chosen UPS Batteries supplied by Standby Systems