Questions tagged [backup]

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

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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 ...
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0 votes
1 answer
46 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 - ...
-1 votes
2 answers
60 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 ...
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0 votes
2 answers
187 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 ...
4 votes
1 answer
120 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 ...
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2 votes
1 answer
114 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 ...
0 votes
2 answers
162 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 ...
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2 votes
0 answers
38 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 ...
1 vote
2 answers
166 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 ...
0 votes
1 answer
166 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 ...
0 votes
1 answer
96 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 ...
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1 answer
86 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 ...
1 vote
0 answers
31 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? ...
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1 vote
2 answers
84 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 ...
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0 votes
1 answer
98 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 ...
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1 vote
1 answer
252 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 ...
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2 votes
1 answer
85 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 ...
0 votes
2 answers
185 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 ...
1 vote
1 answer
106 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 ...
0 votes
1 answer
164 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)...
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0 votes
1 answer
85 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. ...
1 vote
1 answer
154 views

Altium Designer Deleted schematics completely

I opened up Altium after a windows update, and received this error: ...
0 votes
0 answers
52 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 ...
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1 vote
0 answers
20 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 ...
5 votes
2 answers
267 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 ...
0 votes
3 answers
224 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 ...
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2 votes
1 answer
88 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 ...
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2 votes
3 answers
1k 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 ...
3 votes
1 answer
193 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 modem, router which have power requirements of 12V 2A and a laptop which has power requirement of a 20V 3.5A. I am planning to use a AC to DC SMPS which is ...
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0 votes
1 answer
174 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 ...
user avatar
0 votes
1 answer
761 views

is it okay 4 years old used UPS Battery filling sulfuric Acid insted of Distilled water?

I've 1250VA UPS where I found 2 battery (12V-9AH). which Is used for 4 and years more. When I brought this UPS it gave almost 80 to 90 minutes backup but now it only lasts for 15 min. so I decided to ...
0 votes
2 answers
155 views

Same mAh, same volt - different current

I need to replace the 18650 battery of one application. The battery doesn't have any marking about volts, mAh or amperes. Because it's 18650, the voltage is fixed - done. mAh - will use 2000mAh (let'...
0 votes
1 answer
204 views

Some basic questions about voltage and lithium power pack

Well, I've been stuck at home and since I've run out of things to do, I've started thinking about creating a simple cheap backup for my modem, router, and desktop fan. Since I've got several lithium ...
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1 vote
3 answers
87 views

crystal oscillator as backup (or with sync)

I have a device that generates a 49.152MHz frequency, but depending on its status it can cut it off from time to time. This frequency synchronizes my MCU's audio devices, but it must never be stopped. ...
1 vote
1 answer
85 views

Replace 173 Wh lead acid battery with 20000 mAh power bank

I have an APC BX1100C 173 Wh UPS that I use for my computer. I also have a 20000 mAh power bank with output voltage of 5 V. What do I need to do to replace UPS battery with this power bank? Is this ...
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1 vote
1 answer
88 views

One battery backup, two garage doors

I have made a very simple battery backup for my garage door: 2 x 12 V batteries in series connected to the battery terminals of my opener. This charges the battery and switches to backup on power ...
1 vote
1 answer
62 views

Which among the circuit is the most efficient for battery backed up systems?

Which among the circuit is the most efficient one for a battery backed up solution. Would be helpful if you can state the reasons as well. simulate this circuit – Schematic created using ...
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2 votes
1 answer
326 views

Apc backup time calculation

I have APC BX1100C UPS for my pc. it has 2x7.2Ah battery. I have connected to it a router 12v 0.5a, and a monitor 19v 1.3a. Expected it to run 10 hours but it switched off after 2 hours. Does it mean ...
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0 votes
1 answer
53 views

Back-up battery

for a project I would like to design a system which would allow me to feed my application's logic rail from a back-up battery if the main battery would somehow stop functionioning (most likely due to ...
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-3 votes
1 answer
81 views

Changeover relay circuit

I am looking for a circuit for one of mine typical application. I have transformer power supply with 230VAC/DC input with 12V /1A and 5V/500mA output. Now I wanted to introduce another stand by power ...
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0 votes
1 answer
43 views

Need help with terminology so that I can source a din rail version of this part

Im looking for a 12 VDC power supply that has the ability to switch to a battery when ac power is lost in addition to having some type of AC status function such as an open collector. This part does ...
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1 vote
0 answers
63 views

Power supply charging backup power - current flow via mosfet

I have following diagram on falstad Top +5V is main PSU (12V 10A). Bottom +5V is battery (12V 2.3Ah). I have load about 2-3A so I dont think diode is good solution. Well I am trying to achieve ...
0 votes
0 answers
708 views

esp-12 power supply + backup by 4F capacitor 5.5v + ME2149, is it working?

I made my own energy meter using esp-12, I need to save data to esp spiffs when loss grid power, In this case, I do not need wifi than esp turn to modem-sleep mode, so working current is about 20 - ...
0 votes
1 answer
1k views

how to switch to backup battery when power fail?

I have a project running with MCU supplied with a 24V power supply regulated via an SMPS to 9V also, I have Li-ion battery pack 9V how to connector these two sources to run the MCU with battery pack ...
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1 vote
2 answers
377 views

What happens to the backup time when batteries are connected in series?

I have a backup power system consisting of a charger, a battery and an inverter. The inverter powers my load (a few mains appliances). Currently I am using a 12V 200 Ah battery which gives me a backup ...
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2 votes
2 answers
293 views

Switch to battery when voltage supply drops certain threshold

I have made this circuit but can't quit make it work. Vext is my main supply from a car (9 - 14V) Vbat is 8 AA batteries (10 - 13V) Vout supplies power to a SMPS As it is now, supply "fades" between ...
-1 votes
2 answers
4k views

What will happen if I powered a 24VDC device from a 27.8VDC power supply?

I have a device which has a power input from 12-24VDC Auto select and 250 mA load. I connected it with an online DC UPS which has an output of 27.8 VDC on grid mode and 24 VDC on Battery Mode. I ...
3 votes
1 answer
437 views

Integrated 5V uninterruptible power supply (UPS) with a lithium cell?

I'm trying to figure out the best way to implement a UPS for an embedded system that runs from a 5V supply. Essentially the system has a 48v to 5v, 1.2A output DCDC converter that powers my system. ...
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2 votes
1 answer
97 views

Ebedded Linux: Recoverable, battery backed-up RAM (/tmp) [closed]

I hope this is an appropriate place for this question as it involves the use of the kernel. I have an embedded system with a battery backup for the RAM chip. The battery also allows for the MCU to ...
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0 votes
2 answers
121 views

What would be the safest method to power a laptop (IdeaPad 510 15isk) from a 14.8v battery pack?

Looking at my existing power jack and measuring it crudely with a cm ruler it looks like 3mm diameter x 1 cm length. The laptop bottom and charging adapter both say 20v @ 3.25 A max. What would be ...