How to choose a battery for UPS

    The battery is the most important component of the UPS. And the most expensive. In addition, also having a certain life cycle. So, sooner or later, the question of replacing the battery will certainly arise.
    Good batteries serve for many years, why not look into tomorrow to understand what will happen to our investments in hardware? It often happens when something good is very expensive, and after a while it becomes easily accessible.
    When choosing a UPS, the question arises: which battery is used in it, and which one is suitable for replacement?
    Therefore, for a start we will talk a little about technologies and types of batteries.

    What are the battery UPS
    "Stuffing" from the battery is different. Let's start with the most common - with lead-acid batteries .

    Their advantages have long been known: they hold the voltage well, have a small self-discharge and a high duration of work cycles. Some of them withstand up to 1000 recharge cycles, are able to work at a wide temperature range. Yes, and their technology is well developed, which makes the battery more reliable.
    But there are drawbacks. First of all it is low specific capacity, large weight and size. And they need to be changed after a complete discharge.
    But nickel-cadmium batteries are the opposite: small and light. They are also quite reliable, resistant to temperature fluctuations, can withstand up to 1500 charge-discharge cycles, have a low percentage of self-discharge and a fairly significant energy density. In addition, these batteries are inexpensive.
    But there is a minus - these batteries lose their capacity due to the "memory effect".

    In addition, the price may not always be an indicator of high performance characteristics. Take for example, nickel metal hydride batteries. These are expensive devices with high energy density and specific capacity, which practically does not decrease during operation. However, battery data is little used just because of operational difficulties. This battery is full of flaws. First, it is a high level of self-discharge and a small load capacity. Secondly, there is dysfunction during full discharge and a small number of recharge cycles. Thirdly, charging such a battery is not an entirely trivial task. Fourth, temperature sensitivity.
    But the small temperature range is a trouble not only for nickel-metal-hydride batteries, the same “suffer” andlithium ion batteries. Which, by the way, can only be stored in a charged state.
    With that, lithium-ion batteries have a lot of advantages. The main ones are increased specific capacity with small dimensions and weight, high energy density and low self-discharge rate, fast charging, number of charge / discharge cycles, ability to work at high temperature - up to 40 ° C. In addition, they are quite reliable and inexpensive to maintain.
    Previously, “uninterruptible power supplies” on lithium-ion batteries were used only in expensive solutions, but this year Schneider Electric launched the first low-cost single-phase UPS models with lithium-ion batteries with a capacity of 1 kVA and 1.5 kVA with a pre-installed network card - SRTL1000RMXLI-NC and SRTL1000RMXLI and SRTL1500RMXLI with and without it - SRTL1500RMXLI-NC.

    After the battery types became clear, it is worth mentioning that the most popular lead-acid batteries may differ in the type of electrolyte used. These are usually AGM or GEL batteries or liquid electrolyte devices. What are the features of different options?
    In batteries with a liquid electrolyte , dilute sulfuric acid is used. And the danger is that the devices are not tight, there is a risk of harmful substances in the environment. Accordingly, maintenance and charging of such batteries is possible only in special rooms. But they are inexpensive, what explains their popularity.
    In a GEL battery, the electrolyte aggregate has a gel structure. During the work, it does not produce volatile compounds, their shells are completely sealed and gel batteries are completely harmless to humans. In addition, these batteries are powerful, reliable - service life up to 12 years, capacious, can often recharge and operate in almost any temperature conditions. But there are also drawbacks: they are contraindicated for complete discharge and they are quite expensive.
    Compared to GEL, AGM batteries are relatively inexpensive. They are also produced on a gel basis and have low electrical resistance. In addition to the price, AGM-batteries have a lot of advantages: they are durable, have a large capacity, resistant to vibration and are ready to be placed in any position.
    At the same time, AGM batteries work in a buffer mode, because they have a large number of recharge cycles and low self-discharge rates. Plus - they do not have the “memory effect” already mentioned.
    But AGMs have their drawbacks. They are little susceptible to recharging and are not adapted to compensate for part of the electrolyte lost.
    In general, the comparison of GEL and AGM is given in the table.

    Compatibility of UPS Batteries
    Knowing the advantages and disadvantages of the different types of batteries mentioned above, APC by Schneider Electric develops and supplies to the Russian market UPS with lead-acid AGM batteries. There are exceptions to this rule: the recently launched SRTL UPS with lithium-ion batteries. Also, large three-phase UPSs can be configured to work with any batteries, depending on the conditions of use and the wishes of the customer.

    For different UPS, the manufacturer implies the use of different batteries, full information is given in the compatibility tables of batteries, which are produced by the manufacturers themselves. Here, for example, a table on the battery from APC by Schneider Electric.

    It is worth noting that some simple UPS series "Back-UPS", replacing the battery yourself, the user's hands are not provided. To replace, you must contact the authorized service centers. Visually, such a UPS can be distinguished by the yellow battery connector on the back side.

    Advantages of using original battery cartridges
    After discussing the issue of compatibility, you may want to use not original battery cartridges, but the so-called counterparts - products from other manufacturers.
    The advantage of such an acquisition will be only the size of one-time costs. But the risk is added to the whole car.
    Let's start with the main thing - the lack of warranty. APC by Schneider Electric guarantees the proper operation of the manufactured cartridges. The rest is a question. None of the system administrators are not eager to take off and go on their own to change the battery, suddenly out of order, or God forbid, leaked.
    By the way, about compatibility - also another question. The design of the UPS incorporated the parameters of a particular battery. Replacing it with another one can lead to a decrease in its service life, incorrect behavior, and in some cases entail danger. Not to mention that the documentation of "gray" products, as well as on the websites of sellers can be a lot of errors.
    Therefore, it is better to once again recall the advantages of the original batteries. This is a long service life, safety and reliability with a minimum of connectors, compliance with all environmental requirements, confirmed by many tests and certificates. And also, the possibility of easy installation and guaranteed compatibility with your UPS.

    Battery life, how to store, how to maintain
    The life of the batteries with which single-phase APC by Schneider Electric UPSs are completed is 3-5 years, and depends on compliance with the conditions of storage and use, as well as the number of transitions to UPS for battery operation, depth battery discharge in each case, as well as the duration of being in a discharged state.
    In general, the temperature regime is quite critical for battery operation. Practice shows that the battery life for each 8 ° C decreases by 50% when the temperature rises. Be sure to keep in mind that the temperature inside the UPS is always greater than the temperature outside. Also, UPS with online topology and hybrid online sources heat up more than backup or line-interactive ones.

    In the case of storage of batteries at ambient temperatures from -15 ° C to + 30 ° C, it is recommended to recharge the batteries at least once every six months. In conditions when the ambient temperature is between + 30 ° C and + 45 ° C, the batteries must be recharged at least every three months. In order to increase shelf life, batteries should be stored at a temperature of 10 ° C or lower.
    If we talk about large, three-phase UPS, the maintenance and replacement of batteries is critical for the reliability of the entire source. Periodic preventive maintenance not only prolongs the service life of battery chains by preventing loose connections and corrosion, but also helps to identify faulty batteries before they completely fail.
    By the way, although sealed batteries are called unserviceable, this term has got accustomed because they do not need to update the electrolyte. And so, they still require regular maintenance.
    It should also be borne in mind that recharging the battery with a small current leads to a depletion of the chemical life of the batteries and reduces the expected service life by almost half.

    Availability of original battery cartridges and prices for them.
    Returning to the topic of discussion of the benefits of the original cartridges, it should be noted that leading brands also monitor the market. So Schneider Electric has announced a significant reduction in prices for replacement battery cartridges designed for the most popular APC uninterruptible power supplies. Up to 60% cheaper now sold a number of models of battery cartridges.

    There is no universal battery selection board. To solve any problem, you can choose several options: from inexpensive to super-clever. And here it is very important to understand what the initial one-time investments will be and how much the total cost of ownership will eventually be released. The latter is more important in the future, because the UPS are not purchased for one year. The current trend in the development of batteries suggests that batteries on lithium-ion will be cheaper and penetrate all niches, including home use.

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