A UPS is an Uninterruptible Power Supply that provides backup power when the main power source is lost. Questions on repairing commercial ones are generally off topic.

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P-chanel MOSFET series configuration

Good day I'm busy designing a small DC UPS to run some appliances when the power goes out. I am, however, having trouble with an element in the battery switch-over circuit. I decided on using a ...
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0answers
20 views

Using a emergency battery pack as a ups

Ok here is what I am considering. I was looking at using a emergency battery pack as a form of ups or battery back up for a small dc motor used to power a fluidized sand bed filter, which will be the ...
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3answers
32 views

16/18 VAC to 5 VDC UPS

I'm new here so please bear with me. I'm planning to replace my old central alarm system with a new raspberry pi, which takes 5 VDC input. My old central uses a separate 230 VAC to 16/18 VAC ...
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1answer
48 views

Can tranformerless inverter topology be used in UPS with a regular battery (12V 7Ah)?

While searching for transformerless inverters in the IEEE site, most of them seem to be about grid connected Photovoltaic inverters. Removing transformers will increase the efficiency at the cost of ...
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5answers
253 views

seeking help identifying small buzzing transformer from my UPS, or advice on how to silence it

i have an APC brand UPS installed inside another project, and have just recently powered it up for long durations for the first time. and i've picked up an annoying buzz in a small transformer on the ...
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3answers
106 views

Why could a UPS device need of a microprocessor? [closed]

I have read about some UPS devices that are microprocessor-controlled, and I would like to understand the fundamentals of needing such a microelectronical device like a CPU for what it just seem a ...
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1answer
66 views

Rechargeable battery Backup circuit

I have seen this rechargeable battery back up circuit on web.The resistor is used to limit the current.The diode in series is mainly to prevent the back feeding the power supply during battery ...
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1answer
81 views

Transistor UPS circuit

I am trying to create a UPS circuit purely to provide battery power when main input power is lost. I think I've figured out part of the circuit that stops the battery input when the main power is ...
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1answer
54 views

Does one of the battery failure damages the UPS DC capacitor bank? [closed]

Last day i found the DC capacitor bank of the 300kva UPS was burst/damaged.Upon further inspection one of the battery in the battery bank found damaged .My doubt is whether the failure of battery can ...
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1answer
132 views

Raspberry PI UPS

I needed solution to keep Raspberry PI B+ running in case of power loss. So made following power backup circuit: It works, however, when it runs from battery, a bit too much voltage is dropped in ...
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1answer
69 views

Creating an Array from 18650 cells to work with Solar/Wind/UPS [closed]

I originally was asking about the progress of this thread: Creating a large 18650 Array Below is the same information I posted there since I was asked to repost as a new question. Summary: use 18650 ...
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1answer
71 views

Grid changeover switching

I am designing a changeover circuit that will switch the power of attached appliances between two electricity providers. The two AC mains are of 220V RMS voltage and 50Hz frequency sine waves. The two ...
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1answer
65 views

UPS and Inverter power supply sync question

I'm new to this but want to ask this question If i'm having a 3 phase inverter with a battery backup system. does it requires it to sync with the utility power? if yes how long that sync can take or ...
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2answers
143 views

How to modify USB battery pack to function like a UPS?

I bought this USB battery hoping to use it as a uninterruptible power supply for a Raspberry Pi 2. I researched it, and users said it could be charged while also powering devices...just what a UPS ...
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2answers
357 views

How to charge an AGM battery fast?

I have a 12V, 200AH AGM battery. The maximum charging current recommended by the manufacturer is 50 amps. Now, I need to connect two AGM 12v batteries in series to connect to the input of my 24 volt ...
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1answer
117 views

Is an older APC backup UPS likely to be the source of blown fuses in new lab equipment? [closed]

I have new laboratory equipment plugged into an older APC Back-UPS XS 1000. It derives all of its power from this backup system, which in turn is plugged into a regular power outlet. The lab equipment ...
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0answers
145 views

USB battery charger and GPIO power supply schematic for Raspberry Pi

I'm trying to design a circuit in Eagle to provide reliable + safe battery power to a Raspberry Pi via the GPIO pins. The requirements are: Accept power input via micro USB (separate from the Pi). ...
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0answers
47 views

Designing a DC UPS system [duplicate]

My requirements are: I need a UPS system which supplies power to a 9 volt modem. UPS should Charge 12v battery (SLA , charging curent 800ma), and it should have overcharge/discharge protection system ...
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1answer
71 views

What kind of testing equipment is used for UPS (>15 kVA)?

I work at IT division of a bank. Currently we need to order some Double Conversion True Online UPS ( Uninterruptible Power Supply) systems for our our new data center. The required ratings for UPS are ...
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1answer
210 views

Designing 12v DC UPS

My requirements are: I need a UPS system which supplies power to a 9 volt modem. UPS should Charge 12v battery (SLA , charging curent 800ma), and it should have overcharge/discharge protection system ...
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2answers
341 views

Can I safely run a LED light bulb from a UPS? [closed]

I think I blew a capacitor (heard a pop sound) inside a UPS when I plugged in a 29 watt LED light bulb. It still works, but now the UPS is really slow to switch back to AC power after a brownout. ...
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1answer
47 views

600 watts regulated DC for 3 seconds [closed]

In my area, due to frequent storms, there are frequently short mains power cuts lasting a second or two at most. While the shorter several-millisecond outages don't usually cause issues, the longer ...
3
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1answer
275 views

Creating a battery backup unit

I live in a area with frequent power failures lasting up to 5 hours. During this time I would like to power my router so that I can still use the internet with my phone/PC. I've looked at UPS ...
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3answers
469 views

How to automatically switch to backup power? [closed]

To solve the frequent power outages that happen where I live I ended up using a spare car battery I had and a power inverter (one of these). With that I have more that an hour of backup power so it's ...
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1answer
107 views

Intel Atom board (DN2800MT) power supply, can I add battery?

After reading through 20-something posts about 'car/12V/power supply/computer' I've still not found a definitive answer to what I'd like to try here. If this turns out to be a dupe after all, my ...
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1answer
217 views

Supercapacitor circuit modification

I am looking to build a UPS circuit using supercapacitors. I have seen a number of circuits posted online, and a lot of them look very complex (some using lipos, some using NiMH etc). Please note, I ...
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214 views

Prevent desktop from switching off when power inverter switches from mains to backup

I'm using a desktop computer over a power inverter that's connected to a 12V lead acid battery. When the main power supply fails, the inverter switches to battery backup and can power my desktop for ...
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3answers
3k views

Extending the backup runtime of a UPS with an external car battery

I'm looking for a simple/inexpensive way to have a longer power backup time. My fist thought was putting 2 cheap UPSes in parallel. But I quickly found it's not that simple. You would need another ...
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1answer
432 views

Is it possible to connect a UPS in parallel with the mains?

Short version: When a UPS is plugged in to the mains, is it possible to plug the UPS output back to the same mains? Will that work as an emergency power backup for the mains circuit? Longer version: ...
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152 views

Fast Switching For UPS

Well I don't even know how to call this question, but the point is. I am making a DC UPS, and I want to be able to quickly switch from the wall supply to the battery supply, and I don't think a relay ...
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2answers
1k views

Relay not switching immediately from switching power supply to battery backup

WARNING This project as currently described is badly flawed in a number of ways that are liable to lead to complete failure of the equipment. As it is stated that it is intended to be used in a life ...
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1answer
431 views

How do we detect when Power Source from EB to DG

Is there a way we can detect if power source switch from EB to DG? Are there any circuits or alarms already there in market which triggers when the power source changes from Normal Power Supply to ...
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2answers
359 views

Low voltage DC Supercap UPS Design

Most generally I'm looking to design a UPS for a low power DC device given higher voltage AC current, with storage handled by a supercapacitor, or a bank wired in parallel. For my specific case I'm ...
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2answers
414 views

Measuring internal resistance of a battery while it's being charged

I was startled to hear that there are devices out there that can measure the internal resistance of batteries, in circuit, while the batteries are being (trickle-)charged. For example, Hioki markets ...
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3answers
312 views

Rate my Rasberry Pi UPS

I've made simple schematic for a UPS for Raspberry Pi. It contains a 12V Lead Acid Battery (40Ah), 5V LM7805 regulator and some capacitors. I'm supposing max 1.2A load from Raspi. Should I add ...
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1answer
186 views

12V UPS power supply and battery [closed]

I'd like to use a Tripp Lite PR40 as a backup 12V UPS by connecting it to a battery before a couple motors in parallel. The battery is 125AH deep cycle AGM. Can I do this? The manual says that the ...
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2answers
273 views

UPS battery replacement

For the UPS model Niky 900 by Daker, I'd like to replace the original CSB HR1234W F2 battery with something I can buy on amazon.it, e.g. FIAMM models: could you suggest what are the relevant ...
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1answer
188 views

Strange sound in speakers when the refridgerator goes standby [closed]

I live in a room which has two power sockets and the following devices, as illustrated in this diagram: https://docs.google.com/file/d/0Byu0T6y2SLeENDdvNGVCWHFBWmc/edit All devices look exactly as ...
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1answer
647 views

Protecting a wireless router from voltage fluctuation

Background: I have a wireless router ASUS DSL_N12U. Input voltage and current is 12V , 1.5A respectively. I also have an Inverter (works on three modes: Solar, Battery, Mains) at my home. Problem: ...
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2answers
495 views

UPS 12V power switching

I was trying to make a sort of UPS circuit with a 12V DC 5Ah power supply and a 12V 5Ah seal-lead battery. My question is that I don't know how to switch quickly from line supply to battery. I've ...
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0answers
162 views

Switching for UPS battery (without time delay)

I have bought a battery charge up board as here. It provides two modes on the EN pin: 1) ground EN pin, the board will charge up the battery from 5V charge source only. 2) float EN pin, the board ...
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3answers
594 views

UPS batteries and hot/cold weather

I am designing a small network deployment for several buildings without temperature regulation. In planning the power, I can find very little about acceptable UPS batteries for these conditions. ...
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2answers
253 views

Designing a low voltage UPS

Preface: I am designing a UPS such that if the AC main fail the device can continue to run for at least 10 days. My goal here is to make a design that can last years off a non-rechargeable battery. ...
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3answers
116 views

Emergency 3-phase power supply in the event of power failure

I have two Magnum 400 10/20 drivers running two stepper motors. Peak power consumption is about 2 kW. In the event of a power failure on the 3-phase supply, I'd like to trigger a controlled emergency ...
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2answers
282 views

Battery Size for a UPS

I have a 250 VA UPS, and I have a couple of devices I want to run on it, a radio (7 watts) and a fan (55 watts). How do I calculate the required battery size (ampere-hours) (for a 12 V car battery)? ...
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2answers
6k views

Converting Inverter Output from Square Wave to Sin Wave

I bought a UPS, it has output of 220v AC, the problem is the output is square-wave, which causes distortion on TV/LCD, is there circuit that can take this Square-Wave as input, and output Sin-Wave? ...
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1answer
185 views

Is this DSP sinewave inverter a marketing hype?

There are some companies in my country(India) which try to sell inverters for home marketing in the name of DSP Sinewave Inverter and claim are superior to normal sinewave inverters. I am trying to ...
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3answers
163 views

Fallback electronic circuit

I've got a 220 volts fishbowl pump that is conected and working 24x7. However, when a power outage happens (they happen often where I live) I need to switch to a 12 volts version of the same pump, so ...
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2answers
367 views

12v capacitor / UPS system [duplicate]

I am looking to make a capacitor/UPS system for a few different electrical components in my car. I want to power the rear view camera, headrest monitors, and possibly the head unit for about 30 ...
0
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1answer
103 views

Need to know battery configuration for a 250 watts inverter [closed]

I have a 12 Volt inverter which have ability to produce 250 W output. I would like to purchase a battery for this. can any one tell me the configuration of battery ? eg: Minimum AH