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Questions tagged [backup]

For questions about backup circuits, such as a battery backup.

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Automobile 12V UPS circuit with Li ion battery

Currently I have a battery backup circuit for a GPS device to run on automobile power source and I am trying to improve a few things. Any help is appreciated. Currently I am facing issues of negative ...
user387542's user avatar
3 votes
2 answers
519 views

Super capacitors derating

I want to use supercaps in a system for minimal power interruption backup (1-2 seconds). My systems works at - 40 to 85°C. I have seen that supercaps are usually rated for 1000 - 2000 hours at max ...
Uriel Katz's user avatar
1 vote
2 answers
196 views

Why are 2 diodes needed instead of 1 when diode-ORing two power supplies?

I see many circuits online of dual power supplies connected in parallel through output diodes on their outputs, to provide redundancy in case the main one fails. Usually the primary supply is an AC-DC ...
QuickishFM's user avatar
0 votes
0 answers
45 views

5 V to 3.3 V buck with limited input current and large capacitor to cover current spikes?

We need to design a power supply for a 3.3 V WiFi-device. But there are quite some current spikes during WiFi startup. Using the design below there is a risk the 5 V (250 mA max) supply (not mine) ...
boddeke's user avatar
0 votes
0 answers
81 views

How can I isolate internal circuit from external power from L298N?

I have a small simple circuit where an ESP32 runs an L298N driver for a single DC motor (not a stepper.) The run and direction are controlled by a simple web page with two buttons. The code works ...
WouldRatherBuildAMotor's user avatar
1 vote
0 answers
79 views

I want to switch solar panels between a micro inverter and a backup system. How can I do that?

Solar Inverters are switched off during a blackout and make that you have DC electricity on your roof while being without AC in your home. This may not be as urgent where you live, but in countries ...
wogoos's user avatar
  • 71
-2 votes
1 answer
118 views

UPS cord has back-flowing current in it. What to do? [closed]

If the UPS is switched on and it's unplugged from the wall socket, then there's some current in the plug pins as per my neon line tester. It's a three pin plug. The earth pin has no current but both ...
Ojasvi Srivastava's user avatar
0 votes
1 answer
261 views

Design for passive power backup for ESP32 for a few milliseconds

I am designing a logger system with an ESP32 in which the logs are uploaded to the IoT cloud and parallelly logged to a local SD card. On Power loss detection, I want the ESP32 dump all the data that ...
TheBenjamin's user avatar
0 votes
0 answers
69 views

VFD runs has backup generator, breaks down twice

I am Electroman, but very ignorant in electrical knowledge. I have a problem. We have an irrigation pump connected to a VFD that runs on the electrical grid but is connected to an emergency backup ...
electronman's user avatar
1 vote
3 answers
536 views

Backup power supply for car stereo

I built a home stereo for my son using a car stereo and computer power supply. Unfortunately, I lose memory from the head unit every time the power is switched off. From what I understand, I need a ...
Sterling's user avatar
0 votes
0 answers
63 views

How isolate IO pins of Arduino and PSU output?

I will start by saying that I am a beginner of electronics and I don't have much experience hence I am making this post asking for advice from more experienced peopled than me. Now that I have lowered ...
GROZA ALEX's user avatar
1 vote
0 answers
93 views

Connecting multiple DC Sources (DC Bus)

I have a large area which I want to cover with camera and other low power devices. These devices are outdoors, and quite far away from where my intended main power source will be (say 400m). I'm ...
Brandon Kellett's user avatar
1 vote
1 answer
90 views

Looking for a circuit to run a 12 V toilet exhaust fan when utility power fails

I have a tiny house. Recently my inverter failed and it could take weeks or months to have it fixed. It's a 48 V DC solar to 240 V AC, that is intermittently working with a non-working 5 kWh battery. ...
LeoTehJester's user avatar
0 votes
2 answers
105 views

Can I use a power bank to power my laptop during a blackout? [closed]

I am wondering if it's possible to use my ThinkPad L430 laptop with a power bank as a power source during a blackout. The laptop's power consumption is between ~35 to ~42 watts. Its battery is always ...
Kira's user avatar
  • 1
2 votes
0 answers
67 views

5 V holdup/ temporary backup circuit

I have a project where I'm using an android tablet to power a serial relay, the relay is 20 m from the tablet so I'm using a USB C > USB A hub and a self powered USB over CAT6 extender. When the ...
Tim's user avatar
  • 21
1 vote
1 answer
80 views

Short term power supply

As a cheaper or longer lasting alternative to a battery, what else could maintain electricity for a second or two or more for a computer, PS4, TV or other similar devices when the lights are ...
Justintimeforfun's user avatar
0 votes
1 answer
154 views

How does this power supply design work?

While looking at a radio unit I was trying to repair, I found a 5V line at 1.2V. I started to reverse-engineer it, but was later able to obtain the schematic: The right side is the input, and ...
Bartek Banachewicz's user avatar
2 votes
1 answer
832 views

Can I connect a separate charger and inverter to use a LiFePO4 battery as a backup for a household pump?

I have the following equipment and want to know what I need to make this a functional battery backup for a sump pump. 12 V, 100 Ah Smart LiFePO4 battery Victron BlueSmart IP65 Charger 12 VDC, 15 A I ...
cr0's user avatar
  • 167
0 votes
3 answers
875 views

How can I decrease the relay release time when the current on relay coil is reduced slowly?

I'm trying to make a backup power supply for a home WiFi router (12V, 0.5A) and observe that the relay release time for a QYT73 relay is around 1 second. That is enough for the router to reboot, which ...
rodikno's user avatar
0 votes
1 answer
110 views

12 VDC to 380 VAC for 1 kW, 3-phase motor

What is the cheapest way to run a 1 kW, 3-phase motor for about 20 minutes on a 12 VDC battery? Will it be a 2 kW inverter to power a VFD or is there something else? And will a 100 Ah battery do, and ...
Kobus Pretorius's user avatar
0 votes
2 answers
143 views

48 V phantom power backup: switch off the 9 V backup battery with FET

I found this device here on the site. I need something to switch to a 9 V backup battery when there is a 48 V phantom power outage. How can I change the FET to switch OFF the BAT1 (9 V) backup battery ...
Tomi's user avatar
  • 11
0 votes
1 answer
101 views

How to throttle / load balance between utility and battery power supply

Basic queation - What kind of circuit allows me to throttle the power draw from two different supplies? i.e. 80/20 from a battery bank and utility power, respectively? Or 60/40, or 100/0? Main idea - ...
user2657410's user avatar
-1 votes
2 answers
348 views

Leaving super-capacitor connected to power supply

I want to use a 1F-5.5V super-capacitor as a power backup for a 3.3V circuit. As I searched the internet I have to use a circuit for charging the super-capacitor to stop charging when the voltage ...
Vahid's user avatar
  • 289
0 votes
2 answers
2k views

Can I use mains as backup for off-grid solar system?

I want to run 6 freezers/fridges (10kWh/day) with a 4kW array of solar panels, 4x 300Ah 12v LiFePO4 batteries, and a 2kW 12V Projecta Intelli-Wave Pure Sine Inverter. Instead of using a generator as ...
Ryan Adams's user avatar
4 votes
1 answer
596 views

Can a memory backup supercap hold on for more than 2 weeks?

Most RTC chips have a VBATT input for backup power supply; besides a battery, you can use a supercap there, e.g. using the following scheme: simulate this circuit – Schematic created using ...
anrieff's user avatar
  • 5,479
2 votes
1 answer
646 views

Frequency reading 180 Hz on only one line to line measurement in three-phase backup 60 Hz LP gas powered generator in idle mode

I am running into an issue I don't understand why is happening. I have found how to "fix" it, but I am interested in ideas on what the actual source of the issue is Short version: I have a ...
Andrés Marquina de Hoyos's user avatar
0 votes
2 answers
827 views

Automatic battery backup from mains to battery bank on power outage

I've looked for solutions and cannot find anything that's clear to me that accomplishes what we need. Components: 12V furnace 8A load (fan) 120V to 12V adjustable power supply 12V backup battery bank ...
revive's user avatar
  • 113
2 votes
0 answers
44 views

SAM4N Backup Mode - no wakeup

I do have an ATSAM4N and try to go to backup mode as soon as the external power is turned off to keep the RTC time running. Therefore, a battery is added to support VDDIO. I manage to get the SAM4N in ...
Traummaennlein's user avatar
1 vote
2 answers
1k views

12V battery back-up system using a relay

simulate this circuit – Schematic created using CircuitLab I am trying to use a 12V battery as a back up power source. I made this circuit but it doesn't work properly. When the adapter is off ...
abdulmalik's user avatar
1 vote
1 answer
496 views

Adding 12V DC jacks to desktop UPS in order to connect ONU and router

I get a backup of only about 10 minutes when my FTTH ONU and WiFi router are connected on the 220V ports of my desktop UPS. So, in order to avoid the conversion loss, I want to install two 12V DC ...
Aditya Naique's user avatar
0 votes
1 answer
98 views

What parameters to look for in selecting D2 and Q1 for 3500 mA backup power?

Which transistor and diode is suitable for fast switching power and low discharge battery when Vin, for PWM 1.2-29 KHz, 4 A, 3.7-5 V? And which capacitor should be at the output to smooth the ...
Andre's user avatar
  • 35
0 votes
1 answer
184 views

Can an ideal diode pair (evaluation board) be used for backing up one battery with another?

I'm trying to use 2 ideal diodes [within a MAX40203 evaluation kit] for "OR-ing" two battery power sources... to extend the length of time for driving an outdoor flag light. My understanding ...
Gorn'67's user avatar
1 vote
0 answers
33 views

Selecting components for high current backup switch

Does anyone have any pointers or tips on how I can select the correct PNP transistors and resistors for the following circuit? If I need to drive up to 1.5A do I need MOSFETS instead of transistors? ...
P_J's user avatar
  • 25
1 vote
2 answers
98 views

Can I use direct 12V batteries to power PCs/cameras/Raspberries instead of converting to AC and then back to DC?

I'm planning on building a new house. One of the things I want to do is to set a special powerline for all high priority electronics like cameras, PCs, Raspberries (for domotic system.) My idea is to ...
Yind's user avatar
  • 123
0 votes
1 answer
462 views

super capacitor's maximum charge current

I am designing a backup system based on a supercap and an LTC4041. The calculations by the guidlines in the datasheet brought me to the folowing parameters: Capacity:2.4F Charge current: 1A charge ...
metsik's user avatar
  • 173
1 vote
1 answer
648 views

Super capacitor backup circuit

I want to implement a momentary power backup in my circuit using a supercapacitor. I have come up with the following circuit. Am I right in implementing the super capacitor like this? Also, the input ...
Adnan's user avatar
  • 111
2 votes
1 answer
149 views

5V battery backup supply for GPS

I designed a circuit to do the switching from a 12V car battery to a 8.4V Li-Po battery with a relay. Both batteries go through an LM7805 regulator to supply a constant 5V to a Raspberry Pi. When I ...
Felipe_Cortes_Z's user avatar
0 votes
2 answers
448 views

Capacitor as power buffer for battery change

I have a quite simple question and quite a simple circuit in mind. I have an application, which is battery powered and uses a RTC clock for timekeeping. I would like to preserve the time during ...
Kleeblatt Paul's user avatar
1 vote
1 answer
130 views

What could be causing my APCs to buzz from time to time, and for my Tesla to stop charging? [closed]

I have two issues happening at the same time (very much related). The APC brand UPS backups in my office all start buzzing at the same time, then click once every 5-10 minutes. This happens at all ...
billsecond's user avatar
0 votes
1 answer
342 views

Power source switching/isolation circuit

I'm currently designing device which will be powered from external PSU but also will have backup power system from battery. I'm trying to solve my problem. When external power source is down (5V - USB)...
LMatt's user avatar
  • 13
0 votes
1 answer
186 views

2 x 90 Ah 12v deep cycle batteries in series runs 77-90w for under 20 minutes. Why?

I am trying to understand the maths here. I have 2x90Ah 12v batteries in series (24v) and they are powering my computer. The peak power is 120w while the computer is shutting down during a power loss. ...
Eric The Red's user avatar
1 vote
1 answer
617 views

Altium Designer Deleted schematics completely

I opened up Altium after a windows update, and received this error: ...
seacaptain's user avatar
0 votes
0 answers
60 views

230V mains back up with 12V battery and inverter

I am looking to have a 12V battery back up if 230V is lost, to supply a mobile router for security cameras (solar charged battery powered) outside a house when vacant. I have a 130Ah battery in a ...
Joe's user avatar
  • 1
1 vote
0 answers
44 views

Connecting Charger + Inverter to deep cycle battery

It's a really simple question I believe, but I just want to make double sure it's okay. Can one simply clamp a mains charger as well as an inverter onto a deep cycle battery, or does one need any ...
Captain Kenpachi's user avatar
5 votes
2 answers
359 views

Battery Charging Backup Circuit

I am relatively new to electronics and circuits. I'm modifying an alarm clock to have a battery backup. I've found a few circuits that show how to build a battery backup circuit and it makes a lot of ...
namarino41's user avatar
0 votes
3 answers
406 views

Do home UPS (mostly advertised as inverters) have a rectifier built in?

This is regarding home UPS/inverters which are typically known to convert the DC from the battery to AC, so the AC can be used for household purposes. What I don't understand is how the batteries are ...
samshers's user avatar
  • 101
3 votes
1 answer
141 views

Replacing Dallas NVRAM with larger capacity variant?

This DS1225AB-200 (8k x 8 = 64kB NVSRAM) is from 1995 and is probably dead (cannot measure from the outside.) The only close replacement in stock is a DS1230AB-100 (32k x 8 = 256kB.) Looking at the ...
rdtsc's user avatar
  • 16.3k
2 votes
3 answers
3k views

Using two diodes as a simple power supply backup switch

I saw this module as a "battery emergency switch module" for $2 on aliexpress: which is just a relay energized by the external power supply, and when the external supply is gone, connects ...
Tirdad Sadri Nejad's user avatar
3 votes
1 answer
315 views

Will this DC UPS with off-the-shelf components for home network and laptop work?

I am trying to build a DC UPS to power a modem and a router which have power requirements of 12 V, 2 A and a laptop which has power requirement of 20 V, 3.5 A. I am planning to use a AC to DC SMPS ...
rej's user avatar
  • 31
0 votes
1 answer
359 views

DC backup battery switching module

It is common to find these cheap Backup Battery Switching on the internet. But the issue I have with these ones is the load gets reset when switching from the main source to the battery. It seems like ...
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