In trying to make a choice of online UPS, one very common question that comes up is – “How long can this UPS last?”
This question borders majorly on how long the UPS can power loads being run independent of AC power supply.
Providing a “direct” answer is usually not the case in many instances.
This is simply because several factors come to play in determining the backup time of the UPS when fully charged.
[bctt tweet=”Several factors come to play in determining the backup time of the UPS when fully charged.”]
Before we consider the backup time of Gennex 2kVA and 3kVA online UPS, let’s consider some of the factors that affect backup time and how to calculate the backup time of an online UPS.
Factors that affect backup time of the online UPS
1. Battery Rating
UPS batteries are in most cases lithium ion batteries.
These batteries are designed to store charges for use when there is no longer AC supply from the mains or generator.
Batteries are usually rated in Volts(V) with a corresponding Ampere-hour (Ah) rating.
2. Number of batteries
The number of batteries within most UPS ranges from between 2-10 batteries. Some UPS have more.
The number of batteries determine how long the UPS system can power loads run on it.
[bctt tweet=”The number of batteries determine how long the online UPS can power loads run on it.”]
3. Efficiency of the battery
The efficiency of UPS batteries differentiates the performance of online UPS of same ratings. That is why two different UPS types rated 2kVA may not necessarily have the same backup time.
4. Load in Watts (W)
The power rating of the device (appliance) that will be on the UPS determines also how long the it will last without AC supply.
The Online UPS will last longer with lighter loads than with heavy loads.
[bctt tweet=”The Online UPS will last longer with lighter loads than with heavy loads.”]
For example, a 2kVA Online UPS with a load of 200W will last about three times longer than another one with a load of 800W.
How to Calculate Backup time
Backup time of UPS (in hours) = [ Battery rating (in Ah) × Battery rating (in V) × Number of Batteries × Battery Efficiency ] / Load in Watts (W).
As an example, Gennex 2kVA Online UPS has 4 units of 12V/9Ah batteries. It also has an efficiency of 87% in its battery mode. Therefore with a load of 500W , the backup time of the UPS from the formula above is gotten as:
[ 9Ah × 12V × 4 × 87% ] / 500W = [ 9Ah × 12V × 4 × 0.87 ] / 500W = 375.84Wh / 500W = 0.75168h
Therefore, with a load of 500W, the 2kVA will last for 0.75168 hours ( approximately 45 minutes ).
[bctt tweet=”For example, a 2kVA Online UPS with a load of 200W will last about three times longer than another one with a load of 800W.”]
Similarly, with a load of 500W on the 3kVA Online UPS having 6 units of 12V/9Ah batteries and efficiency of 88% in its battery mode, the backup time is obtained as follows:
[ 9Ah × 12V × 6 × 88% ] / 500W = [ 9Ah × 12V × 6 × 0.88 ] / 500W = 570.24Wh / 500W = 1.14048h
Therefore, with a load of 500W, the 3kVA will last for 1.14048 hours ( approximately 68.4 minutes ). This about 52% more time than that of the 2kVA Online UPS.
The decision to buy a good online UPS should not be an afterthought. Buy online ups systems that can provide optimum backup time for specified loads and that can also serve for a long period of time considering that most online UPS tend to experience a drop in performance over time.
The price for Gennex 2kVA Online UPS is 112,000 naira while the 3kVA model costs 142,000 naira.