Four factors affect battery reliability

Yingkou Rijie Group is an international high-tech enterprise integrating scientific research, production, sales and service in Liaoning province.

Many factors affect battery reliability Even though the UPS uses the same battery technology, battery life varies greatly from manufacturer to manufacturer, which is important to users because the cost of replacing a battery is high (about 30% of the UPS selling price). Battery failure reduces the reliability of the system and is an annoyance. Kurt Battery Tech is here to talk to you.

1. Battery temperature affects battery reliability

Temperature has a great effect on the natural aging process of batteries. Detailed experimental data show that for every 5 degree Celsius increase in temperature, battery life decreases by 10%, so the UPS should be designed to keep the battery as warm as possible. All online and backup/online hybrid UPS operate with more heat than backup or interactive UPS (hence the need for fans), which is an important reason for the relatively long battery replacement cycle of backup or interactive UPS.

2. Battery charger design affects battery reliability

Battery charger UPS is a very important part of the battery charging conditions have a great impact on battery life. UPS battery life can be improved even more if the battery is kept at constant voltage or in a "floating" electrical charging state. In fact, the battery life in charge state is much longer than that in storage state. Because battery charging can delay the natural aging process of the battery, the UPS should keep the battery charged whether it is running or down.

3. Battery voltage affects battery reliability

The battery is composed of a single "primary battery", each of which has a voltage of about 2 volts. The primary battery is connected in series to form a battery with a higher voltage. A 12-volt battery is composed of 6 primary batteries, and a 24-volt battery is composed of 12 primary batteries and so on. When the UPS battery is charged, each primary battery connected in series is charged. The slightly different performance of the galvanic battery will lead to the charging voltage of some galvanic batteries is higher than that of other galvanic batteries, and this part of the battery will age in advance. As long as the performance of a single primary battery connected in series declines, the performance of the whole battery will also decline. The test proves that the battery life is related to the number of primary cells in series. The higher the battery voltage, the faster the aging.

When the UPS capacity is fixed, the design should make the battery voltage as low as possible, so that the UPS battery life is longer. For the battery voltage is fixed, the battery with a small number of galvanic cells in series should be selected, not the battery with a large number of galvanic cells in series with low voltage. Some manufacturers of UPS battery voltage is relatively high, this is because when the capacity is certain, the higher the voltage, the smaller the current, you can choose a finer wire and smaller power semiconductor, so as to reduce the cost of UPS. The battery voltage of a UPS with a capacity of about 1KVA is generally 24-96V.

4. Battery ripple current affects battery reliability

Ideally, to extend UPS battery life, the battery should always be kept in a "float" or constant voltage charge state. In this state, a fully charged battery absorbs a small amount of the charger's current, which is called a "float" or "self-discharge" current. Despite the battery manufacturer's recommendation, some UPS are designed (many in line) so that the battery is subjected to some extra small current, called ripple current. Ripple current is generated when the battery continuously supplies power to the inverter because, according to the principle of conservation of energy, the inverter must have an input direct current to produce an AC output. This gives the battery a small charge-discharge cycle, with the frequency of the charge-discharge current twice that of the UPS output frequency (50 or 60Hz).

Normal backup, in-line interactive, or backup/ferromagnetic UPS will not have ripple currents. Other UPS designs will have ripple currents of varying sizes, depending on the design method. Just check the UPS structure drawing to know whether the UPS can produce ripple current.

If the battery of an in-line UPS is between the charger and the inverter, then the battery will have a ripple current, which is normal for a "dual transform" UPS.

If the battery is separated from the inverter by a cutoff diode, relay, converter, or rectifier, the battery will not have ripple current. Of course, this design is not always "online," so it is called a "hybrid backup/online" UPS.

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