And the conversation will go not about external batteries, but internal - autonomous power supplies of the UPS themselves. The most interesting thing is that manufacturers of such products promise long-term operation of their devices, but in fact they cannot “live” normally for a couple of years. Well, what is the reason, we must figure it out ourselves, which we will do.
The technical part - a little theory
To proceed to considering the problem, you need to understand the following parameters: what is the initial current and voltage of the battery charge. And also understand whether the battery should be recharged if it is fully charged.
The voltage of the charger usually does not change, but the current strength can be different. And to charge the battery from the very beginning with high currents is to quickly disable it. Usually they start with low currents and gradually reach the nominal value. But if the voltage fluctuates, then insignificantly, no more than tenths.
Now we need to understand the following question: should there be a recharge in the uninterruptible power supply? Answer: yes, but this parameter should be adjusted very precisely, otherwise a too high level of recharging will shorten the battery life significantly.
Why batteries fail quickly
It's all about the wrong charge voltage, incorrectly set by the manufacturer. For example, this indicator of Chinese UPS models can reach 14.5 V, while this value should not exceed 13.7-13.8 V.
With an increased charge voltage, the temperature of the battery can also increase, which adversely affects its operating life, or rather, the state of the lead plates inside the device. Unfortunately, the consequence of the high temperature at the source can be not only an increased charge current, but also the presence of a number of other overheated electronic elements.
How to save an uninterruptible power supply
In order for your uninterruptible power supply to serve for a long time and reliably, you need to make several minor modifications.
1. Adjust charge voltage. The problem is not easy and requires minimal knowledge of electronics. A small potentiometer must be installed on the control board of the uninterruptible power supply, by scrolling which you can adjust the same potential difference. To set the value correctly, you will also need to connect the test leads of the multimeter to the battery terminals.
2. Provide additional ventilation for the internal UPS. To do it in a simple way, it is enough to drill a number of holes in the metal case of the uninterruptible power supply. But you can also install the fan by completing the control circuit separately from it. This method is quite problematic and not everyone can perform it, but there will be many times more benefits from it.
In order not to make additional modifications, it is better to initially buy expensive, high-quality products with a long operational and warranty period. Then you don't have to rack your brains and delve into troubleshooting with their subsequent elimination.