Among the variety of UPSs, the most common in entry-level server rooms are Smart UPSs from APC (now Schneider Electric). Excellent reliability and low price in the secondary market contribute to the fact that system administrators, without much thought, stick racks with UPS data and try to extract maximum profit from 10-15 year old hardware by banal battery replacement. Unfortunately, this does not always give the expected result. Let's try to figure out what and how to do so that your UPS works "like new".
Battery selection
All articles and topics on the forums about choosing a battery for UPS most often resemble topics on choosing engine oil for auto / motorcycle. Let's try not to be like them, but to understand the basic principles for choosing batteries using the example of the manufacturer CSB.
We see a bunch of different battery lines from them: GP, GPL, HR, HRL, UPS, TPL.
Let's start reading: GP, GPL - batteries for universal use for small and medium discharge currents. Recommended for use in security and fire systems and UPS. We don't fit. Although they are most often bought without bothering to study their characteristics.
The HR series are batteries with increased energy capacity and deep discharge (up to 11% of residual capacity), especially useful when high discharge currents are required. The difference between "H" batteries is a special grid design that allows for a 20% increase in power output. They are most suitable for use in high-power power plants and UPS.
The letter "L" in the series indicates that these are batteries with an extended service life (Long Life) in the buffer mode of operation up to 10 years.
Well, the UPS series is a specially designed battery for operation in high current mode with a short discharge time.
For myself, I chose between UPS and HRL for a long time, but decided to take HRL. Unfortunately, it will be possible to say how they will behave in long-term work in 5 years, and necroposting seems to be not very welcome. Therefore, we will consider that this is my personal choice and I am not going to impose it. But you must understand that it is necessary to choose high-current batteries, since they must be able to give all the accumulated capacity within 20-30 minutes.
Selection of battery assembly
Considering that several batteries are used in the assembly, it is highly desirable that they have the same characteristics. For one low-quality battery will lead to the fact that the entire assembly will not work at all as expected.
About 5 years ago, I discovered the Rostov company Bastion, which produces battery capacity testers under the Skat trademark. I do not presume to assert about the ideal accuracy of capacitance measurements, but to assess the level: ideal-living-still serve as a corpse, this tester is more than enough.
In principle, it is possible to measure the capacity with a banal charge-discharge using a watch, a 21W car lamp (it gives a load of about 1A) and a tester, but this is long and most often lazy.
Well, in extreme cases - we just try to install fresh batteries from the same batch and hope that you are lucky.
Electrical is the science of contacts
One bad contact in an assembly of 4 batteries will negate all your attempts, so we disassemble the assembly very carefully. Typically, UPSs use battery connectors with latches, which are just as easily transferred to the dead state by simply pulling them out. Therefore, we take a small flat screwdriver, insert it into the connector as in the photo and carefully remove it without applying much effort. As a colleague suggested in a comment, you just need to pull on the plastic casing, and not on the wire. The connector is removed with a slight click.
Well, about the correct connection of the wires, I think it's unnecessary to write. If you climbed inside the UPS, then you obviously know the principle of series connection of batteries. And for the rest: a piece of paper, a pen or a smartphone with a camera. At the end of the assembly, just in case, we measure the voltage on the assembly with a tester and compare it with the one that should be, based on the number of batteries.
βI did everything as written, but it did not helpβ
Well, now the fun begins. UPS, in the course of its work, periodically (usually every 7 or 14 days, depending on the setting) conducts a short battery calibration. It switches to battery mode and measures the voltage immediately and after a short time. The result of this is a certain correction factor for "battery life", which he enters into his register. In the process of gradual battery dying, the state of this register gradually decreases. Based on it, UPS calculates the remaining battery life. And then at one fine moment, realizing that everything is bad, the UPS lights up the indicator with the requirement to replace the battery. But when we make a replacement, UPS doesn't know about it! The status of the "battery liveliness" register remains the same. We need to fix it.
There are two ways. The first way, simple and fast - it is necessary to carry out a full calibration of the UPS. To do this, you need to load it by more than 35% and start the calibration, for example, from the PowerChute program. It works about half the time. Why not always is a mystery shrouded in darkness. Therefore, let's take a long, but more reliable path.
We will need: a computer with a COM port, a proprietary cable (for example, 940-0024C, UpsDiag 2.0 program (for the safety of your UPS, a colleague recommends using apcfix in free mode. I canβt say anything about this, except that I categorically do not recommend clicking in UpsDiag something other than editing 0 case, especially the battery auto-correct button) and . We are interested in the value of the register 0. The table shows the value for ideal, spherical batteries in a vacuum. Any real batteries will give a value less after calibration, but not by much.
For example, I'll take a real UPS SUA1500RMI2U. At the time of the battery replacement, UpsDiag showed the register value 0 - 42. That is, the batteries are dead. The calibration value from the table is A1.
We start to correct. First thing remove network card from UPS. The presence of a network card will not give you the opportunity to edit the register. Why is a question for APC engineers. Fortunately, you can pull it off hot without turning off the UPS.
We connect the cable, run UpsDiag, go to the "Calibration" tab and look at the state of register 0. We write it down on a piece of paper, right-click on it - Change. We raise it to the value from the table of calibration values ββ- A1. If your UPS is not in the table, then in principle you can raise it to FF. Nothing terrible happens from this, except for the freaking UPS, which will show that it is ready to hold the load until the second coming.
Then we need to wait until the battery is charged to 100%, load the UPS up to 35% or a little higher and start the calibration. At the end of the calibration, we again look at the value in the 0 register and compare it with the one written on a piece of paper. In the SUA1500RMI2U described above with new HRL1234W batteries, the value became - 98, which, in principle, is not very far from the calibration A1.
After everything, we let it charge up to 100% again, pull off the COM cable, plug the network card back in and wish UPS a long and happy life for the benefit of our server rack.
By the way, network cards like AP9619 in the secondary market have also fallen in price to indecent values. But how to prepare them (password reset, firmware update, settings) is the topic of a separate article.
Source: habr.com