UPS Battery maintenance
How to maintain the battery, what is the normal life?
- Under normal conditions, the battery should be charged and discharged every 3 to 6 months, and the charging time of the standard machine should not be less than 10 hours after discharge.
- If the UPS is not used for a long time, it should be charged once every 3 to 6 months.
- The battery operating environment requires a temperature between 0°C and 40°C, avoid direct sunlight and keep it clean.
- Generally at room temperature, the floating charge life of Panasonic sealed maintenance-free lead-acid batteries is 3–5 years in normal use.
- Can the UPS use water-filled batteries?
Yes, but users are advised to use maintenance-free batteries. Because the user forgets to add water, the battery acid water leaks or the battery gas discharge is not good, etc., it may cause the battery to die or affect the normal operation of the UPS load. In addition, the charger of Santak UPS is designed for the characteristics of lead-acid batteries, so it is not suitable for other types of batteries.
- Is there a formula for calculating the specific discharge time of the UPS?
Because the battery discharge time is related to many factors such as discharge current, ambient temperature, load type, discharge rate, battery capacity, etc., the actual discharge time cannot be directly derived from the formula. The formula for the maximum discharge current of the battery is now provided: I=(Pcosφ)/(ηEi)
where P is the nominal output power of the UPS;
is the load power factor, generally 0.6~0.7 for PC and server;
is the efficiency of the inverter, which is generally taken as 0.8 (Sant 10KVA takes 0.85);
Ei is the end-of-discharge voltage of the battery, which generally refers to the voltage of the battery pack.
Substitute the specific data into the above formula, and after obtaining the maximum discharge current of the battery, the corresponding discharge time can be found from the relationship diagram between the discharge current and the discharge time at each temperature of the battery. Please note that what is calculated here is the total discharge current value of the battery. When multiple sets of batteries are connected externally, the discharge current value of a single set of batteries is required.
- Can UPS choose alkaline batteries?
This problem is divided into two situations: one is that users need to use Santak’s monitoring software. In this case, after using alkaline batteries, the battery parameters displayed by the monitoring software will be different from the actual situation. This will bring trouble to users. The second is that users do not need Santak’s software. Because the discharge characteristics of alkaline batteries are quite different from those of acid batteries. The time from the battery discharge to the alarm point (the UPS beeps every second) to the automatic shutdown of the UPS is very short, and the user must pay special attention during use; in addition, alkaline batteries usually need to be refilled (usually every two years). inconvenient.
- How to maintain the battery after dual-system hot backup?
- During hot backup, the main unit and the backup unit can use battery packs of different capacities, but you need to pay attention when discharging.
- A large-capacity battery should be matched with the backup machine. Once the main machine fails, the backup machine can continue to supply power for a long enough time. In actual situations, the probability that the host machine is usually powered by batteries due to changes in the mains is significantly greater than that of the backup machine, that is, the backup machine is rarely able to automatically switch to battery power. Therefore, the battery maintenance of dual-machine backup is mainly for the backup machine. The specific methods are as follows: Backup machine battery maintenance:
(1) In the mains mode, press the main engine power button for 1S, the main engine will switch to the inverter bypass state, and both the bypass indicator and the inverter indicator will be on. (2) Press the power button of the standby machine for 1S, the standby machine will switch to self-check until the battery low voltage mode. LINE, BYPASS, BATTERY, INVTER LEDs will cycle.
(3) There are two ways to release the battery maintenance status of the backup machine:
A: Manually, press the power button again for 1S respectively, then both the main and standby machines will switch to Line INV-Mode.
B: Automatic, when the backup machine discharges to the cut-off protection voltage, the active and standby machines will switch to Line INV-Mode; when the utility power is abnormal or interrupted, the active and standby machines will switch to BAT INV-Mode (battery power supply mode).
Use and maintenance of batteries
(1) Types of batteries and their advantages and disadvantages
The battery is an important part of the UPS system. Its pros and cons are directly related to the reliability of the entire UPS system. However, the battery is the device with the shortest mean time between failures (MTBF) in the entire UPS system. If the user can use and maintain it correctly, it can prolong its service life, otherwise its service life will be significantly shortened. The types of batteries are generally divided into lead-acid batteries, lead-acid maintenance-free batteries and nickel-cadmium batteries, and their respective characteristics are shown in Table 3.
Type Overview Advantages and Disadvantages
Lead-acid battery 1. General battery, also known as automotive battery
- Need to add water for maintenance
- Expected life is 1-3 years 1. Hydrogen will be generated during charging and discharging, and the placement site must be equipped with an exhaust pipe to avoid danger
- The electrolyte is acidic and will corrode metals
- Need to add water frequently for maintenance
Lead-acid maintenance-free battery 1. New battery
- No need to add water
- Expected life is generally 5-7 years 1. Sealed, no harmful gas will be generated when charging
- It is easy to set up, and there is no need to consider the ventilation problem of the placement site
- Maintenance-free, maintenance-free
- High discharge rate and stable characteristics
- Higher prices
Nickel-cadmium battery 1. Advanced battery, used in special occasions and special equipment
- Need to add water
- Expected life is 20-40 years 1. Water is the medium, and no harmful gas will be generated by charging and discharging
- The water loss rate is low, but it takes a fixed time to add water and maintain
- The best discharge characteristics
- Can be placed in any harsh environment
- Extremely expensive
Considering factors such as load conditions, use environment, service life and cost, lead-acid maintenance-free batteries are generally selected. Users must not choose inferior batteries for cheapness, because doing so will affect the reliability of the entire system and may cause greater losses.
(2) Inspection of the battery
Batteries have self-discharge phenomenon. If they are not used for a long time, energy will be lost, so they need to be charged and discharged regularly. Engineering and technical personnel can judge the quality of the battery by measuring the open circuit voltage of the battery. Take a 12V battery as an example. If the open circuit voltage is higher than 12.5V, it means that the battery has more than 80% energy storage. If the open circuit voltage is lower than 12V, it means The energy storage of the battery is less than 20%, and the battery is already at the point of “running out of ammunition and food”.
Because the maintenance-free battery adopts an absorption electrolyte system, no gas will be generated during normal use. At this time, the internal pressure of the battery will increase, which will open the pressure valve above the battery, which will seriously cause the battery to swell, deform, and deform. Leakage or even rupture, these phenomena can be judged from the appearance, if the above situation is found, the battery should be replaced immediately.
(3) Use and maintenance
Although maintenance-free batteries do not require special maintenance work by humans, there are still certain requirements for use. Improper use will affect the service life of the battery. The factors that affect the service life of the battery are as follows: installation, temperature, charging and discharging current, charging voltage, depth of discharge and long-term charging.
· Battery installation
Batteries should be installed in a clean, cool, ventilated, dry place as much as possible, and should be protected from sunlight, heaters or other radiant heat sources. The battery should be placed upright and not at an angle. The connections between the terminals between each battery should be firm.
· Ambient temperature
The ambient temperature has a great influence on the battery. If the ambient temperature is too high, the battery will be overcharged and gas will be generated; if the ambient temperature is too low, the battery will be undercharged and the service life of the battery will be affected. Therefore, the ambient temperature is generally required to be around 25°C
· recharging current
The battery charging current is generally expressed as a multiple of the battery capacity C. For example, if the battery capacity C=100Ah and the charging current is 0.1C, it is 0.1×100=10A. The optimal charging current of lead-acid maintenance-free battery is about 0.1C, and the charging current must not be greater than 0.3C. Too large or too small charging current will affect the service life of the battery.
· Charging voltage
Since the UPS battery belongs to the standby working mode, the mains is in the charging state under normal conditions, and will only discharge when the power is off. In order to prolong the service life of the battery, the charger generally adopts the constant voltage current limiting method, and the battery will turn into a floating state after being fully charged. , For a battery with a rated voltage of 12V, the float charging voltage is set to about 13.7V. If the charging voltage is too high, the battery will be charged, otherwise the battery will be insufficiently charged. The abnormal charging voltage may be caused by a wrong battery configuration, or due to a charger failure Therefore, when installing batteries, the specifications and quantities of batteries must be correct, and batteries of different specifications and batches should not be mixed. Do not use low-quality external chargers, and consider heat dissipation when installing them.
· Depth of discharge
The depth of discharge also has a great impact on battery life. The deeper a battery is discharged, the less it will be cycled, so deep discharge should be avoided when in use. Although there is generally a battery low voltage protection function, generally when a single battery is discharged to about 10.5V, the UPS will automatically shut down, but if the UPS is in the case of light-load discharge or no-load discharge, it will also cause deep discharge of the battery. In normal use, it is necessary to prevent the occurrence of unexpected conditions, such as a short circuit of the battery.
· Regular maintenance
The battery should be checked regularly after a certain period of use, such as observing whether its appearance is abnormal, measuring whether the voltage of each battery is average, etc. If the battery is not powered off for a long time, the battery will always be in a charged state, which will deteriorate the activity of the battery. Therefore, even if the power is not powered off, regular discharge tests are required to keep the battery active.
The discharge test can generally be carried out once every three months. The method is that the UPS is loaded – preferably more than 50%, and then the mains power is disconnected to make the UPS in the battery discharge state. The duration of discharge depends on the capacity of the battery, generally from a few minutes to several tens of minutes. After discharging, restore the mains power supply and continue to charge the battery.