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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Is it okay to connect a smaller UPS to a bigger UPS? [migrated]

At my office we have two UPSs, one has 10x 12v Batteries with 50Ah capacity connected to the big one, and a smaller 600VA Desktop UPS. Some small networking equipment is plugged into the smaller one ...
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1answer
97 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
74 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
59 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
74 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
44 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
57 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
143 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
150 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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0answers
88 views

Li-ion powerbank UPS + DC boost converter

I have a philips cordless landline phone and its power rating mentioned in its OEM ac-dc adapter says output of 6v 500mA. the problem is that in my place we have intermittent power failure, and since ...
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1answer
46 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 ...
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1answer
172 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
214 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
85 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
140 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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0answers
138 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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2answers
1k 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
247 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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1answer
138 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
752 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
215 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
253 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
239 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
258 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
155 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
187 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
147 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
450 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
333 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
126 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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2answers
388 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
228 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
104 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
197 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
5k 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
151 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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2answers
316 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 ...
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1answer
83 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
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1answer
4k views

50/60Hz inverter output inductor design

Given a SMPS PWM inverter (for example an UPS) supplying voltage/current at 50/60Hz, how do you design an output inductor? I don't mean how you compute its value in uH/mH nor its current rating in A. ...
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3answers
335 views

Diode rating for a UPS project with extra battery

I am planning to add an additional 12volt deep cycle battery to my APC UPS but I dont want to use the charging circuit built into the UPS. I think that if I throw in a Diode between the external ...
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1answer
971 views

Backup power for adsl modem

I want to create a circuitry for switching to backup power (small battery) in case of mains power failure for my ADSL modem (to avoid the internet going down in such scenario). This is a basic ...
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1answer
62 views

Can I use a UPS to compensate for unsteady line-power? [closed]

One of the outlets in my home provides unsteady power that causes connected electronics to occasionally shut down. If I buy a battery backup device such as this will it be able to compensate for ...
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1answer
574 views

Humming Sound of UPS vs DSP Inverter

I have a APC 1000VA BR Smart UPS.I have noted that the UPS Produces a Humming Sound when running on Battery Power.But my older a normal 500VA UPS(not from APC) seems to produce far lesser humming.The ...
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1answer
1k views

Will a PSU with Active PFC Work with Normal UPS

Im getting a Seasonic SII 620 with Active PFC.The problem is that i have a pseudo sine wave ups or just a normal UPS.Will this PSU work with the back up power offered by the UPS?
3
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2answers
269 views

Buffering AC supply voltage and detect power loss?

I'm designing a system integrating: an industrial PC with 230V AC input (~300W) various peripherals requiring 24V DC (150W max) In case of external AC power loss, the DC components (2) need to be ...
2
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2answers
157 views

Is it possible to charge 3 parallel batteries without sending charge to the UPS?

I have a UPS (uninterruptible power supply) with a 220VAC input designed to be used with 12V batteries. It has a rated capacity of 400 watts and I've placed three 12V car batteries in a parallel ...
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3answers
885 views

Convert 320VDC to 220VAC or 48VDC voltage using 220VAC (UK) UPS?

I've got access to 12 flexible Solar Panels - 320VDC each Main voltage is 220VAC (here in the UK) and also might buy an electric engine running at 48VDC. Would a 220VAC Uninterruptable Power Supply ...
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2answers
468 views

Trouble using marine batteries with UPS

First, let me premise this question with the fact that I'm not well versed in electricity. Here's the problem: I am trying to power a UPS with an inverter and two deep-cycle batteries run in ...
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3answers
604 views

Is there an instrument that can measure the capacity of lead acid batteries

Background I have an electrical scooter with 6 x 12Volt lead acid batteries (72 Volts total), which are now in such a condition that they can barely get me to my work and back. I got a bunch of used ...
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1answer
890 views

Will a trickle charge lead-acid battery system last?

If I were to implement a simple battery backup system like this to power several WiFi radios in a field situation, how would the battery handle it? Would trickle charging it like that wear it out ...