Why shouldn't the UPS battery be connected in parallel?

Time of issue:2022-07-13


Can UPS be connected in parallel?

Theoretically, UPS batteries can be used in parallel, but due to the individual differences of batteries, service life and other factors, it will not be easy to balance between batteries, which will affect the service life. What are the advantages and disadvantages of parallel use?

Under the same charging voltage, the charging current of each of the two groups of batteries used in parallel is different. The charging current of the battery with large internal resistance is small, and that of the battery with small internal resistance is large. In this way, it is possible that the battery with low charging current is often in a state of insufficient charging. Over time, this battery may suffer from long-term power loss and sulfation, which may increase its internal resistance. The larger its internal resistance is, the smaller the charging current is. Due to such a vicious cycle, the service life of this battery is greatly shortened. This is not the case with only one set of batteries.

Therefore, it is recommended that users should not use two batteries in parallel when they can use one battery to meet the needs of the equipment, otherwise it will not only shorten the service life of the battery, increase the use cost, but also reduce the comprehensive performance of the battery.

Of course, it is understandable for designers and users to consider improving the reliability of standby power supply. In case of AC power failure, one of the two batteries can not supply power, and the other battery can be used to ensure it, even if it is worth doing something costly. If we consider using battery packs in parallel from this point of view, we only agree to use more two batteries in parallel. If more than two batteries are in parallel, it is harmful and useless. If you have to use two batteries in parallel, please also follow the following principles:

1. the batteries used in parallel must be produced by the same manufacturer and of the same model and specification;

2. the batteries used in parallel must be in the same state as the old ones;

3. the same batch number is delivered at the same time;

4. to install and use at the same time.