UPS Batteries: Questions and Answers

3,5 or 10 years when referring to a UPS battery is a general term used for high specification EUROBATT and IEC compliant lead-acid batteries with regard to their in-service life-expectancy when they are designed and built for use in Riello UPS systems. Batteries compliant with these standards guarantee the user peace of mind. Although the UPS backup batteries are generally more costly, they are of a much higher build quality, better performing, and have a longer design life than standard batteries.
These compliant batteries have a design life of 12 to 15 years, are built in flame-retardant PVC casings with threaded Cu insert for the main terminals, and are most popular in high spec UPS installations where reliability is a major factor.

There are many things that affect the sizing of a UPS backup system. These include:

  • The accumulated overall inverter load to be connected.
  • The type of loads to be connected to the inverter.
  • The type of backup, i.e., a short duration of 5 to 30 minutes just to allow time to safely shut down the load when the power goes off, or long battery backup to carry the load through load shedding.
  • If the load is highly critical, then one may want to consider a parallel redundant UPS plant so that if one UPS should fail, the load will still be protected by the other parallel UPSs.

It is very important to choose the right UPS technology for the load you wish to connect. Different technology UPS systems offer different levels of load support and protection – along with higher pricing as the technology gets better.

UPS technologies commonly available nowadays are:

  1. Off-line UPS: offering least load protection overall and only short battery backup of 5 to 30 minutes, inverter load dependant.
  2. Line-interactive UPS: offering more load protection. Often with built-in Automatic Voltage Regulator (AVR), it features quicker switch-on times and is also suited to short-duration load backup on power failures of 5 to 30 minutes, inverter load dependant.
  3. Online double-conversion UPS offering full load protection, no switch-on time, and available for short battery backup or long battery backup of several hours.

Another important factor is to ensure that the UPS is not sized too large for the actual connected load, as a UPS running at 25 to 50% load is very inefficient and has high running costs due to high inefficiencies at low loads. Ideally, the inverter should be running between 60 and 75% of the actual power rating.
Suppose you’re not sure what size UPS you need. In that case, Standby Systems have a highly competent team of UPS technical sales engineers, specialising in UPS systems for all applications, from small 1-phase Riello UPS units for your home or small office to large 3-phase UPS power plants. Our specialists will visit your site free of charge to assist in your UPS sizing. Contact us or email us, and we will send a free UPS load calculator. Using the calculator, you can select the loads you want to connect to your UPS to determine the UPS size you need.

Galvanic isolation is the use of a double-wound transformer, generally on the UPS output inverter, to isolate the load from the UPS battery power. Should an inverter short-circuit, there is a chance that the load will be subjected to high DC (battery) power, which will certainly damage any sensitive load connected to the inverter. The isolation transformer prevents the DC from doing this and acts like a one-way valve allowing only AC power through it.
Galvanically isolated UPS systems, like the Riello MPT, MHT, and MHE ranges, are widely used when high-demanding power is required by the inverter load, such as mixed building loads, motors, air conditioners, medical imaging loads, and other industrial loads like plasma cutting machines, etc. The inverter output transformer makes the UPS far less susceptible to these harsh loads and is a more reliable solution and lower cost, long term, than a transformer-free UPS inverter.
Harmonic filtering is necessary for large 3-phase UPS plants to limit the amount of “electrical noise” that the UPS rectifier generates back into the ESKOM power grid. This noise can be so bad that it will prevent a building’s power factor correction equipment from working, which results in huge unnecessary electricity costs.
This noise can penetrate other equipment connected to the building’s supply and affect its operation; causing overheating of UPS supply cables and UPS supply distribution boards. Its effects cannot be seen with the eye, but they are nasty overall and easily avoided using a UPS with a total harmonic current distortion back into mains of less than 3%. In years gone by, this was achieved by using a 12 pulse UPS rectifier, but this has been replaced with a far more effective component, namely, an IGBT rectifier.
Battery autonomy or battery backup in a Riello UPS system refers to the amount of time the load will continue to run even when the ESKOM supply goes off. The longer the battery backup to the UPS inverter, the higher the cost. Ideally, if one experiences frequent power failures every day or a few times a week, then the UPS should be used in conjunction with a generator so that the battery backup is only for a few short minutes while the generator starts, i.e., the UPS is only there to bridge the gap in power, not supply power for hours.

If it is not possible to run a generator in conjunction with a UPS, then a long battery backup will have to be considered. This is an expensive and limited option, with many long term costs, because:

  • A normal, affordable UPS battery can only undergo about 200 to 300 full discharges
  • A long battery backup system requires a lot of space
  • Big battery banks are more of a fire risk
  • UPS Batteries must be recyclable in South Africa, so use only lead-acid products
  • UPS Batteries require replacement every 3 to 8 years usage dependant, leading to a high total cost of ownership

An uninterruptible power supply, also known as a UPS system, is primarily aimed for use in protecting the sensitive IT/electronic and other connected inverter loads from the following:

  • Power failures
  • Brownouts or short loss in power
  • High spikes, or transients, caused by lightning and the switching of high voltage switches on the ESKOM grid
  • General bad power as experienced in areas near to or in heavy industry, such as arc furnaces, etc.

The UPS acts as a filter and prevents the connected inverter load from “seeing” the bad power supply while using the battery backup power to carry those situations of power supply loss and ensure the load keeps running unhindered by the battery power being supplied from the UPS inverter.
A UPS thus protects its connected inverter loads from bad power or loss of power supply. It prevents software corruption, data loss, injuries in production, loss of production, loss of time, equipment damage, and many other things.

An air conditioner, or any motor with a start/stop load, is a very harsh load that distorts the mains supply due to its very high current demands on start-up, and often regeneration of power back into the mains supply when it switches off – also called a regen load. These high start-up currents normally exceed the UPS inverter’s ability because, although it can cater for peak loads, it can only supply a certain amount of peak inverter load for a very limited time.
For this reason, it is not advisable to put an aircon or start/stop motor load into a UPS. One way around this is to put a variable speed drive between the UPS and the motor load which will soft-start on the inverter and protect it. Alternatively, a generator is the preferred supply option for these types of loads.
In South Africa, we have become used to the words “load shedding”, “inverters”, “backup power”, “solar”, and “off grid”.
What does the word “load shedding” actually mean in the context of UPS SYSTEMS OR UPS PLANT? Well, the answer is simple. A UPS inverter will usually have a certain quantity and variety of loads connected to it that need clean power filtering and reliable inverter power backup when the lights go out.
In most cases, many of these loads do not necessarily need to be kept running; they just need to be protected from bad power or sudden loss of power. Under power failure conditions, these loads can be shut down in a controlled manner, either manually or via the Riello Powershield and Watch and Save software (which is freely available), or a UPS network interface or SNMP card, which is optional on purchase or can be retrofitted. This software is a powerful UPS tool that can be easily and safely used to power-down less critical loads during a power failure in a controlled manner, thus increasing available battery backup time for the inverter loads that must run continuously. This process is known as UPS load shedding in order to increase available battery backup time
An ATS is a device that allows for 2 input supplies and 1 output supply. In UPS systems smaller than 10 kVA, the ATS is generally a 19-inch rackmount device with 2 sources of input, i.e., UPS 1 inverter connected to input 1 and a UPS 2 inverter connected to input 2. These devices have several IEC plug outlets to plug loads into. With IT and Datacentre equipment being highly critical but often only having one power supply, the ATS at least allows the equipment connected to its output to have two UPS supply sources in case one of the UPSs should fail. Click here for more information.
Another form of ATS is called an STS or static transfer switch. It is far more advanced than the ATS technically, and designed for use in higher-power single- and three-phase applications, usually in conjunction with a UPS feed to input A and another UPS feed to input B. Read more here.

Since UPS systems were first designed and built, they were always made with an inverter output transformer. This had two functions:

  1. The transformer was used to step up the inverter output voltage to 220/400 volts supply for what we use here in South Africa.
  2. The transformer galvanically isolated the load from the UPS battery, thereby protecting it.

Nowadays, transformer-based UPS like the Riello MPT, MHT, and MHE have a third positive effect in that they create a new neutral for the critical connected inverter load, bringing the neutral much closer to the load. This drastically reduces the effect bad neutrals can have on the functionality of critical data centre, IT and software loads.
With the Riello MHE UPS, there is the added advantage that this UPS system is extremely efficient and has low losses, with a small footprint making it ideal for use in Datacentres where space is expensive and precious.
All Riello transformer-based UPS systems can be installed up against the wall, making them more space-efficient. They also only require front access for servicing and 500mm clearance above the top of the UPS for fan airflow and cooling.

In more recent years, transformerless or transformer-free UPS systems have been developed, with most manufacturers moving away from transformer-based UPS systems. This newer technology is far cheaper to produce and thus more competitive. This technology is also more efficient and requires a smaller footprint.
However, in most cases, the smaller footprint doesn’t necessarily mean less room space use, as almost all UPS systems with transformerless technology require front, side and back access, plus rear clearance for fans exhausting hot air. Essentially, they take up less floor square meterage but need more room area around them.
They are very efficient, which is very important in the green energy UPS world we live in. Still, they can easily and more effectively be replaced in high power ranges with more reliable and robust transformer-based Riello MHE flagship products, which give the user peace of mind, offering both high reliability with ultra-high efficiencies – the best of both technologies in one.
In the field, transformer-based UPS units tend to be far more reliable than transformerless UPS units. They are generally only used when connected to inverter loads that are highly demanding and harsh on the inverter. They are more costly, so the cheaper alternative is generally used for most UPS backup applications.
To begin with, it is necessary to put together a list of all the loads that need to be protected by the UPS from power failures and bad power supply from the grid. This list of UPS inverter loads is known as the critical loads, and it is essential they have inverter and battery backup when the power fails. It is important to remember that UPS and battery backup are ‘essential components’, so it is important to be 100% sure the selected critical inverter loads are the absolute minimum. No luxuries are allowed for in the sizing. Any other load that is not required when the power fails is a non-critical load.
The total power draw of the selected critical loads is obtained by making a list of the power rating of each piece of equipment. This detail can be obtained from the rating plate, normally at the rear or under the device, or off the power supply feeding it. Once you have the list, add it all together, and that will be the total power draw to select on the UPS. If you have a problem with sizing, you can email Shaun and request a UPS sizing calculator to assist you in your sizing.
Once you have the total power draw added in watts, you can select the UPS size accordingly. It is important to allow 30% on top of the calculated power draw to accommodate when loads startup, resulting in higher than normal inrush currents on the UPS inverter. If the total power draw is in watts, you need to divide this by 0,7 to get to the VA size, which is what UPS units are generally rated in. A UPS up to 3 kVA is a plug-and-play device and doesn’t require installation. Units of 4 kVA and upwards require an electrician to hard-wire the UPS into your building.

Some types of loads have very high inrush currents on startup or just draw far more power than other items the same size, for example:

  • Laser printers
  • Air conditioners and pumps
  • Lighting including LED lighting, which draws what is known as a leading power factor
  • Certain types of servers such as blade servers
  • Motor loads

If connected to a UPS, these kinds of loads will cause it to go to bypass continuously, giving constant alarms. They will also affect inverter operation while under power failure conditions during battery discharges. The best way to cater for such loads is to either leave them off the UPS completely or calculate their peak instantaneous power draw on startup and include this in your sizing. This peak is often not normally stated on the device power rating and must be obtained from the manufacturer, or you can contact Shaun for assistance or email us to arrange a site visit by a technical sales engineer from Standby Systems.

The battery backup time is the period of time for which you need to keep your loads on inverter battery backup, up and running. This could either be for several hours to bridge an entire power outage or for the time it takes for your backup generator to start up and take the load, which is normally less than 5 minutes. If the load doesn’t have to run all the time in a power outage, but just for long enough to allow time to shut down properly, a backup time of 10 to 30 minutes is generally used. The backup time sized at full UPS inverter load is ironically affected positively if the actual running loads are reduced to a minimum under a power failure scenario. Load reduction results in a non-linear battery discharge, so for example, a UPS battery sized for 5 minutes backup at full inverter load will get far more than 10 minutes backup at 50% inverter load.
UPS Sealed valve-regulated lead-acid batteries, also known as VRLA batteries, are high rate batteries that are an electrochemical device. ELITE brand is an example. All batteries contain a liquid known as electrolyte. A UPS battery uses a technology called starved electrolyte, whereby the amount of liquid inside is minimal, and therefore it is not considered a spillable device. A UPS battery is designed to run at an ambient temperature of between 20 and 25 degrees Celsius over its service life. When it is operated at temperatures higher than 25 degrees Celsius, the electrolyte will evaporate at an accelerated rate. This causes a pressure build-up inside the battery, forcing the emergency valve to open and purge the gas. The loss of gas means loss of liquid in the battery, and the battery will dry out much faster than normal, causing premature failure of the battery. UPS batteries operated at over 30 degrees Celsius will achieve less than half their expected service life.
An automatic-voltage-regulator (AVR) device, also known as an automatic voltage stabiliser (AVS), is used to keep the grid supply power feeding your loads within acceptable voltage limits of +/1 10% of the 220 VAC nominal for your connected loads, even if the grid supply varies by as much 220 VAC plus 20% over rated voltage and 220 VAC minus 40% under voltage. Most decent AVRs also include filtering circuits for noise on the grid supply side to prevent it from affecting your load. It is very important to remember that an AVR or AVS is not a UPS. They will not keep your load running when the power fails and have no inverter or backup battery.
RIELLO UPS systems, distributed throughout Southern Africa by Standby Systems, are covered by a full parts and labour replacement warranty.
The single-phase Riello UPS range, including Sentinel Pro, Sentinel rack, Sentinel dual low power up to 3 kVA, is covered by a 24-month ex-works warranty with an optional extension to 36 months upon request at time of purchase.
The single-phase Riello UPS range Sentinel Dual or SDU and Sentinel Tower or STW are covered by a 12-month warranty with an optional extension of up to a maximum of 5 years upon request at time of purchase.
The three-phase Riello UPS range, including Sentryum, MST, NXE, MPT, MHT, and MHE, is covered by a 12-month warranty with an optional extension of up to a maximum of 5 years upon request at the time of purchase.
On-site warranties for Riello UPS units installed outside of South Africa may be subject to certain conditions specified in the Standby Systems terms and conditions at the time of quotation.
All warranties are subject to preventative maintenance being done according to the manufacturer’s specifications with chargeable services contracted by the user to Standby Systems as the authorised service provider. Such services are not included under the warranty cover or equipment sale pricing. For more information contact our service department.
A 12-month full replacement warranty covers all ELITE UPS batteries, provided they are installed and operated under a UPS float application environment. Cyclic applications void any warranty unless the battery is sized correctly at the time of purchase for such an application.
Some ELITE UPS batteries are available with up to 3-years individual block warranty replacement.
All warranties are subject to preventative maintenance being done in accordance with the manufacturer’s specifications with chargeable services contracted by the user to Standby Systems as the authorised service provider. Such services are not included under the warranty cover or equipment sale pricing. For more information contact our service department.
What are the differences between the two main UPS configurations i.e. a parallel system (N) and a parallel redundant system (N+)?
A Parallel uninterruptable power supply system (N) consists of one or more units in parallel, such that all the units are needed to supply the full load and should one unit fail the system will transfer to bypass leaving the load on raw mains supply.

A Parallel redundant system (N+X) means that should one or more units fail up to the number equalling the +X, the load will remain safe on inverter supply and the system will not go to bypass, keeping the load protected. i.e., there is redundancy of UPS modules.

What are the advantages of using a separate external wrap-around maintenance bypass with your UPS plant?
  1. It allows for 1005 electrical isolation of the UPS plant from the AC power supply and inverter connected load.
  2. It doesn’t require downtime.
  3. Risk-free switching and isolation without any back-feed power into the inverter.
  4. Simple and easy to manufacture.
  5. For single-phase systems, it is available as a standard unit in-rack or tower mount 16 amps 220 VAC.
What causes a battery to fail?
There are many reasons why a battery does not achieve the design life whilst in service, but the main factors that adversely reduce service life include factors such as:

  1. High temperatures
  2. Number of discharges and depth of discharge
  3. Incorrect maintenance
  4. High battery charger ripple voltage due to poor quality build chargers
  5. Incorrect application of battery product
Can I do anything to ensure my battery lasts as long as possible?
Yes. There are several checks that can be done under regular UPS and battery preventative maintenance visits by Standby Systems to ensure that the battery is at optimal performance and will be available if the power supply fails to keep the UPS inverter running. There are also optional testing regimes that can be done such as impedance measurement to determine the battery’s internal state, and thermal imaging analysis.
What is a UPS unit?
An uninterruptible power supply unit or UPS system is an emergency power backup system using a combination of a rectifier to charge a battery and an inverter to feed clean filtered AC Sinewave power made from the battery backup power to the critical load when the power supply fails.
Why do I need a UPS?
All electronic and computer-controlled loads require a clean filtered power to operate smoothly and prevent hardware damage and software corruption due to bad power and power failures. Without a UPS critical loads would have much shorter service lives and would not operate under power failure conditions like in rolling blackouts.
How much battery backup time do I need?
UPS systems are available with a large variety of backup battery times from 5 minutes up to several hours. The longer the backup time the bigger the battery and the higher the purchase price.
How long will my UPS battery take to recharge?
A UPS battery is a lead sealed battery that can NOT recharge within less than 72 hours to 100% capacity, no matter what make or how big the battery charger is.
Which type of UPS technology should I use?
There are 3 main types off UPS technology, i.e., offline, line-interactive, and on-line double-conversion. Offline is the cheapest but offers the least protection to the inverter load. Online is the most expensive and offers best protection but the choice is normally dictated by budget and the value of the connected load.
What voltage can my UPS give me?
A standard UPS in SA will run at 220 VAC input and 220 VAC output 50 Hz. It is possible by special order to get a 110-volt unit, but it is not a common stock item.
Is it cost-effective to replace the batteries in my line-interactive or offline UPS?
When it comes to low-cost, entry-level, desktop UPS units, it is often not cost-effective to replace the UPS battery when it is at end of life and no longer gives backup, depending on the labour cost to do the replacement. If you replace it yourself, it will be cheaper, but please ensure that you recycle the battery at a legitimate disposal outlet. Most entry-level UPS units use one or two 12-volt sealed lead-acid batteries, which are low-cost. Sometimes the labour to replace them, added to the cost of the batteries, works out more expensive than buying a new UPS. If you opt to buy a new UPS, ensure you remove the batteries from the old one and dispose of them responsibly at a trustworthy recycling outlet or they will swell and leak acid, causing damage to anything they come into contact with, and harming the environment.
Is it cost-effective to replace the batteries in my Desktop online double-conversion UPS?
Most Desktop UPS systems are plug and play from 1 to 3 kVA rating and normally use between 6 and 12 batteries inside of 12-volt sealed 7 or 9 AH batteries. The cost to replace these batteries is substantial compared to the cost of a new UPS with the added cost of the labour to do so. It is, therefore, advisable to unplug your unit when its battery is at end of life and take it in to your supplier to change the battery bank and dispose of the old one for recycling.
What are the risks when I replace my UPS battery?
If the battery change is done by a qualified person, then there is very little risk, and the process can be done safely. However, with hardwired UPS systems or any UPS where the load is still connected while the battery is being changed, there will be no backup power during the process, so if mains power fails, you will lose your load. Other risks associated with changing a battery include connecting them wrong, causing a short circuit, which can burn your hands, damage the UPS or even damage the load.
How do I know when my UPS unit battery needs to be replaced?
Batteries are unpredictable and will work today but fail tomorrow, creating a weak link in a UPS system as opposed to the modern electronics that are exceptionally reliable nowadays. It is a good idea to test the battery by switching off the mains supply to the UPS every few months, and ensuring the output stays on. More advanced UPS units allow you to perform a battery test from the front panel.
What does it mean when my battery time gets less every day during rolling blackouts?
If you are discharging your UPS battery every day during rolling blackouts, and each day your backup time for the same load gets less and less, there are several possibilities:

  • Your battery was not sized correctly for daily discharges.
  • Your battery was not sizzed big enough for the connected inverter load.
  • Your UPS battery charger is too small for the battery connected.
  • Your battery cannot recharge in one day because it is limited by the maximum recharge current it can receive or it will be damaged.
  • Your battery is old and at end of life and needs replacement.
What type of batteries are used in my desktop or rackmount plug and play UPS?
A desktop or rack mount UPS will usually have batteries fitted internally and sometimes in an add-on battery pack. These batteries are normally 12 volt 7 or 9 Ah sealed lead-acid batteries. They are available in general-purpose (GP) or high rate (HR) or high-rate long-life (HRL) battery versions with the GP being the most cost-effective type of battery.
What type of batteries are used in my hardwired UPS?
Any UPS from 5 kVA upwards needs to be hardwired into the building’s electrical power supply – it cannot operate from a wall plug because of the amount of power. There are various battery types that can be used on these systems, but normally, single-phase UPS systems up to 10 kVA have simple battery chargers and are thus suitable mainly for sealed lead-acid battery types.
Larger UPS systems, like 3-phase units, have bigger, more complex rectifiers that can charge many types of battery options. These include:

  • General-purpose sealed VRLA lead-acid batteries.
  • High-rate sealed VRLA lead acid batteries.
  • High-rate sealed VRLA long-life lead-acid batteries.
  • Vented or flooded lead-acid Plante’, Tubular and flat-plate batteries.
  • Nicad batteries – But these cannot be recycled in SA.
  • Lithium technology batteries – But these cannot be recycled in SA.
What are the most cost-effective UPS batteries?
The most cost-effective battery to use in a UPS application is by far sealed, lead-acid VRLA batteries. This is the most widely used and popular UPS battery technology with sufficient ex stock availability and comparatively low total cost of ownership, whilst being easily recycled in South Africa.
What is a VRLA battery and what does it mean?
VRLA stands for Valve Regulated Lead-Acid which means the battery is sealed and can be installed standing up or on its side in length without being damaged or leaking acid. This is the most popular and widely used UPS battery and is both cost-effective and low maintenance, whilst being easily recycled anywhere in the world.
What is an AGM battery?
AGM stands for Absorbed Glass Matt which is the technology used in a sealed lead acid VRLA UPS battery that holds the battery acid in suspension, much the like the gel in a baby’s nappy. Therefore, if the battery is punctured, no acid will run out as it is not free running. The AGM battery is also referred to as a starved electrolyte battery as the amount of liquid inside it is minimal i.e., it is starved of electrolyte volume that is held in suspension.
Can my UPS operate without its battery?
Although an uninterruptable power supply (UPS) is intended to ensure power continuity to the inverter’s critical load, it makes use of battery power to do this when the mains fails, most modern UPS units can run without a battery connected, in which case they will only ensure clean sine wave power supply to the load. If the mains fails or dips, the load will be dropped.
What does a UPS battery cost?
UPS lead-acid VRLA batteries vary in price according to the ampere-hour or AH which is the amount of stored energy a battery can hold to supply the inverter when the mains fails.

12-volt 7AH UPSEL UPS battery will cost around R150-00 each.
12-volt 9AH UPSEL UPS battery will cost around R190-00 each.

12-volt 98 to 105 AH ELITE high-rate UPS battery will cost around R 1400-00 to R 2200-00 each.
(Prices valid at time of publishing.)

Costs will vary according to the exchange rate, lead price per tonne index, battery technology and life expectancy, i.e., general purpose (GP0, high-rate (HR), high-rate long-life (HRL), thin-plate pure-lead (TPPL), etc.

How long will a UPS battery last?
A UPS battery is designed to last either 3 to 5, 10, or 15 years, depending on the design life (how it is built in accordance with international standards) and service life (actual life achieved in the field). The cost of the battery increases with increased design life. It is good preventative maintenance practise to replace a battery when it is at end of design life as it could then fail at any time.
What is battery design life?
A battery design life is how the battery is assembled and what materials are used to build it, along with which design criteria the manufacturer’s design complies. A battery that is built in accordance with Eurobatt standards is considered a high-quality reliable build.
What is battery service life?
Battery service life is the actual service life achieved in the field. The same battery used in different environments with different inverter load profiles and power supply reliabilities will achieve different service lives. If a battery is sized to backup a UPS for a certain time on an occasional basis, also called a float charge application, compared to the same battery type used where it is subjected to regular daily discharges during rolling blackouts, called cyclic application, the float charge application will reach end of life much closer to design life whilst the cyclic battery may only last 10% of the design life before it needs replacement.
Can my UPS be damaged if I ignore my failing battery?
If a UPS battery is failing or has failed it will have undergone some internal chemical and electrical changes which will mean that it will draw more charge current than it should. In this situation, it will heat up and, with the heating up, will draw more current – this cycle will result in a battery meltdown and possible fire due to thermal runaway. The battery can also explode and contaminate the inside of a UPS or UPS battery room with lead and acid, often resulting in damage to property and internal UPS components.
Must I keep my UPS plugged in all the time?
It is essential that your UPS is plugged into the mains supply to at least charge the batteries even if the inverter is off or there is no load connected. If this is not possible, then it should be switched on about once every 2 months for 3 to 4 days for the batteries to charge. If the batteries are left without any charge for more than 3 months they will undergo a an irreversible process called sulphation which will damage them and effect their performance with premature failure being the result.
What are the physical signs of VRLA battery failure?
When a VRLA UPS battery is failing or has failed, it will start to swell and, if it is in a really bad state, the lid will pop out.

If the amount of backup time is diminishing, even if the battery is carrying the same load on the inverter as when the battery was new, this is also an indication that the battery is failing, provided it is not being discharged more than once every 72 hours.

Other ways to determine if a battery is failing:

  • Perform a battery impedance test.
  • Perform a thermal scan.
  • Do a discharge of the battery into a DC load bank.
  • Check if battery voltages are all different.
What is a battery impedance test?
As a VRLA battery ages, its internal resistance and capacitance, also known as impedance, increases from when it was first manufactured. A special impedance tester that measures all factors, including temperature, can be used to determine the impedance of a battery. The measurements are compared to that of a new battery to determine the internal state of a lead-acid battery and how close it is to end of service life to prevent failure and no backup power.
When should I do a battery impedance test on my 3-phase UPS system?
Battery impedance testing should be done from about mid-service life expectancy onwards, in addition to normal preventative UPS and battery maintenance, to determine the internal state of the battery and detect any signs of failure. Test intervals are site- and test result-dependant, but at least once per annum or biannually is recommended.
How can I charge my desktop UPS internal battery?
The easiest way to charge a UPS battery fitted internally is to plug the UPS into mains and switch it on. The UPS will take about 72 hours before its sealed lead-acid battery is 100% charged.
Can my inverter battery recharge fully by the next day after a 4-hour rolling blackout?
Generally, normal lead-acid batteries cannot recharge fully within 20 hours. So, under rolling blackout conditions, it is common to find batteries “failing” after a few days of power failures. So called deep-cycle batteries are part of the lead-acid battery family and offer no advantage when it comes to daily cycling as they physically cannot recharge in 20 hours.
What battery products are green and easily recycled in SA?
The only battery type that can currently be recycled in SA is lead-acid. Lithium, Nickel Cadmium, and other technologies are not recyclable locally, and are very expensive to return overseas for recycling as they are considered hazardous waste when at end of life. The only green choice in Africa for any UPS or inverter battery, is lead-acid VRLA.
What is a good cycling battery to use in my UPS unit that is recyclable locally in SA?
The only battery that is resistant to cycling and will fully recharge every day within 20 hours is a lead-carbon UPS battery.
How long will a 100AH battery provide power before going flat?
The backup time given by a battery is dependent on the amount of load that is connected to your inverter. If an inverter has only 100-watts or less load on it then a 100AH battery will last for many hours. However, if it has a 1000- or 2000-watt load, the battery will only last a few minutes.
What does a small UPS battery cost?
A good quality 7 AH battery will cost less than R200-00, 9AH will cost under R250-00 and a 98AH about R 1 500-00. (Prices valid at time of publishing.)
What is the best way to select a UPS size for your house?
When selecting a UPS for your house, you need to separate your critical load from the luxuries. For example, any heating or cooling, like geysers or air conditioners, are not viable to put on a UPS. They use too much power and would need a battery that costs as much as a small house to provide backup power for 4 hours. Normally you would only want to put one or two LED lights, Wi-Fi router, a TV, and a decoder onto a UPS to carry you through the 4-hour rolling blackouts. Anything else is a luxury which is unaffordable to most.
How many batteries does a UPS use?
Different size UPS systems use different quantities of batteries. A UPS battery is normally 12 volts and is used in a series combination for batteries inside a UPS or, in the case of bigger systems or where long battery backup times are needed, the battery bank will consist of up to 4 series stings in parallel. A small 650 VA UPS will use only 1 or 2 12-volt batteries, while a 10 000 VA UPS will use as many as 40 batteries in series.
What does ampere hour, or AH, mean with a battery?
The AH is the amount of power the battery can deliver in amps of DC power for a period of hours. For example a 100AH battery will deliver 10 amps for 10 hours at 12 volts DC.
How long can a line-interactive UPS run a router for when the power fails?
A Wi-Fi router draws about 25 watts and will run for 3 to 4 hours during a power failure when supplied by a 2 kVA line interactive UPS with an internal battery.
What is a deep cycle MF battery?
A deep cycle battery is a battery that is built with thicker lead plates so that it can supply long deep discharges.
Is a deep cycle battery the right battery for rolling blackouts?
No, a deep cycle battery needs 72 hours to fully recharge after a full discharge, so it cannot recharge in 20 hours to 100% state of charge. Generally, no lead-acid battery can be charged at more than 10% (0,1C) of its ampere hour rating up to an absolute maximum of 20% of its ampere hour rating (0,2) or it will be damaged permanently.
What is a good combination of UPS and home inverter?
A Pureline modified sinewave inverter unit paired with a lead-carbon battery is the best combination for a reliable home solution to support your Wi-Fi router and laptop during daily 4-hour rolling blackouts, so you can continue to work unhindered from home.
What is AGM in a battery?
AGM is a type of lead-acid battery technology commonly used in batteries. It stands for Absorbed Glass Matt and is used in sealed battery products so that the acid inside the battery is not free running. The acid it is held in suspension, much like a baby’s nappy holds liquid without leaking. This common type of modern storage battery is also referred to as a starved electrolyte product because, if you make a hole in the battery, no acid should leak out as it is held in the AGM.
Is a deep-cycle Delkor battery sealed like an AGM battery?
No, this is a flooded automotive battery technology with lots of acid liquid inside. If it falls on its side or gets punctured, sulphuric acid will leaking out.
What does VRLA mean?
VRLA means Valve Regulated Lead Acid and refers to the most common form of lead-acid used today for all types of applications including UPS, Telecomms battery, starter battery and many other usages. This is a sealed product that can be installed upright or on its side in standby power backup applications.
What does battery depth of discharge or DOD mean in terms of a UPS battery backup?
Depth of discharge is the amount of capacity or power reserves which is taken out of a battery from its fully charged state when it is discharged. DOD is used to determine the battery’s state of charge once discharged and helps determine the time it will take to recharge the battery to 100% of full capacity.

The higher the DOD, the more capacity is taken out of the battery, the longer it will take to be fully charged again. During rolling blackouts, it is essential to rather have a very low depth of discharge of no more than 20% to try and ensure that the battery is full by the next day’s power outage.

Contact us