Methods of effectively prolonging the life of UPS battery pack

Methods of effectively prolonging the life of UPS battery pack

Regular inspection

Check the terminal voltage and internal resistance of each cell regularly. For 12V cell batteries, if the terminal voltage difference between cells is more than 0.4V or its internal resistance is more than 80m Ω, the cell batteries should be charged evenly to recover the internal resistance and eliminate the terminal voltage imbalance between cells. The charging voltage is 13.5-13.8v during equalizing charging. Most of the batteries with good balanced charge treatment can recover their internal resistance to less than 30 m Ω.

During the operation of UPS power supply, the above imbalance caused by the change of battery characteristics of each unit over time can no longer be eliminated by the internal charging circuit of UPS power supply, so the imbalance degree of batteries with obvious imbalance of this characteristic will become more and more serious if the off-line equalizing treatment is not taken in time.

Re float

The UPS power supply is shut down for more than 10 days. Before restarting, the UPS power supply shall be started without load to use the charging circuit in the machine to float charge the battery for more than 10-12h and then operate with load.

UPS power supply is in floating charge state without discharge process for a long time, which is equivalent to "storage for use" state. If this kind of state lasts for a long time, the battery will fail and be scrapped due to "too long storage". It mainly shows that the internal resistance of the battery increases, which can reach several Ω in severe cases.

We found that at room temperature of 20 ℃, after storage for one month, the usable capacity of the battery is about 97% of its rated capacity, if it is not used for six months, its usable capacity becomes 80% of the rated capacity. If the storage temperature increases, its usable capacity will also decrease.

Therefore, it is suggested that the user should deliberately unplug the mains input every 20 ° C months to make the UPS power supply work in the state that the battery provides energy to the inverter. However, this operation should not take too long. When the load is about 30% of the rated output, it can discharge for about 10 minutes.

Reduce deep discharge

The service life of electricity is closely related to the depth of its discharge. The lighter the load of UPS power supply is, the larger the ratio of its available capacity to its rated capacity is when the mains power supply is interrupted. In this case, when the UPS power supply automatically shuts down due to the low battery voltage, the battery is discharged deeper.

How can the actual process reduce the occurrence of deep battery discharge? The method is very simple: when the UPS power supply is in the state of mains power interruption, and the battery supplies power to the inverter, the vast majority of UPS power supply will ring a periodic alarm sound with a gap of about 4S to inform the user that the battery supplies energy now. When the alarm sound changes rapidly, it means that the power supply is in deep discharge, and emergency treatment shall be carried out immediately to turn off the UPS power supply. Generally, do not let the UPS power supply work until the battery voltage is too low and the automatic shutdown is finished.

Peak charging with power supply

For users whose UPS power supply is in low voltage power supply or frequent power outage for a long time, in order to prevent premature damage of battery due to long-term insufficient charging, it is necessary to make full use of power supply peak (such as late night time) to charge the battery to ensure that the battery has sufficient charging time after each discharge. Generally, it takes at least 10-12h to recharge the battery to 90% of the rated capacity after deep discharge.

Pay attention to the selection of charger

The maintenance free sealed battery used for UPS power supply cannot be charged with a silicon controlled "fast charger". This is because this kind of charger will cause the battery to be in a bad state of charging, which is both "instantaneous over-current charging" and "instantaneous over-voltage charging". This state will greatly reduce the available capacity of the battery, and in serious cases, the battery will be scrapped. When using UPS power supply with constant voltage cut-off charging circuit, pay attention not to set the working point of low battery voltage protection too low, otherwise, it is easy to produce over-current charging at the initial stage of its charging.

Of course, it is best to choose a charger with both constant current and constant voltage to charge it.

Guarantee the ambient temperature of power supply

The available capacity of the battery is closely related to the ambient temperature. Generally, the performance parameters of the battery are calibrated at room temperature of 20 ℃. When the temperature is lower than 20 ℃, the available capacity of the battery will decrease, while when the temperature is higher than 20 ℃, the available capacity will increase slightly. Different types of batteries from different manufacturers are affected by different temperatures. According to statistics, at - 20 ℃, the available capacity of the battery can only reach about 60% of the nominal capacity. The effect of visible temperature can not be ignored.