Questions tagged [battery-operated]

Involving or pertaining to a circuit or device that is intended to be operated with cells or batteries (as opposed to mains power, for example).

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1answer
494 views

Use a SIM card module (SIM808) with the less battery possible

I'm using a SIM808 module (on a breakout card) and I want to send only 20 bytes every 6 hours (i.e. 120 bytes per day), containing GPS position and some very short other data. So I think I'll ...
6
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1answer
13k views

switch between battery and usb power no microcontroller circuit

Following an earlier question about how to switch between battery and USB power, I would love to implement the TC2014 LDO as suggested by Russell McMahon. That way I could switch between 4AA ...
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1answer
519 views

Never use Ni-MH batteries in a toy? [closed]

This is a simple battery powered toy basically just a DC motor. Never use Ni-MH Batteries Why would Tamiya 4WD JR prohibite rechargable Ni-MH batteries? As I understand it, the voltage is a bit ...
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2answers
594 views

Fake a panasonic battery to revive camera to copy photos from internal memory

Got this camera from a friend, battery door broken, no cables, no battery. There are some important photo's on this camera that I want to copy from internal memory to SD card. We first want to try ...
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1answer
808 views

3 AA batteries vs. USB battery pack?

we have a few LED string lights that use 3 AA batteries and eat through batteries about once a week. I would like to replace the AA batteries with a USB battery pack I have which has about 8,000 MAH. ...
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2answers
536 views

battery lifetime with self discharge

I want to calculate the lifetime of a battery operated device. Without self discharge of the battery, it is easy to calculate the lifetime, it's just the battery capacity \$Q\$ (given in mAh) divided ...
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3answers
1k views

On— off— on— off timer circuit

I want to make a circuit to do something that is relatively simple but I need to find the optimal way to do it in order to take as little current as possible. Here is what I want to do: When a ...
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1answer
67 views

Can I use the same power supply to double the voltage?

I want to do a corded conversion as seen in this link . However, some Makita tools use dual batteries to have a 36V source. That means the voltage from the 18V power supply will be combined to ...
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1answer
2k views

5v Solar Cell Charging a 3.3v Battery while in use will the circuit see 5v instead of 3.3v?

I have a tiny arduino type project that needs 3.3v that needs to run off grid and I have some tiny 5v solar cells, now I plan to put a battery between them to keep it all working 24/7. I was thinking ...
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1answer
287 views

Pull-Down / Pull-Up Resistor value for minimum current leakage

I'm using a step-up converter (MT3608) to convert 3.3V to 5V Output. However, because I don't need the 5V all the time and my device is battery powered, I want to turn off the MT3608 IC through its EN ...
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4answers
4k views

What is the simplest way to turn off some circuit when supply voltage reaches a minimum level?

Knowing I have only a 12V battery to supply my circuit, how I can turn off the circuit if the voltage reaches 11V? I cannot use simple comparator CI since I don't have another supply voltage. I could ...
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2answers
1k views

Drive stepper motor with a battery efficiently

I bought a bipolar stepper motor (Mercury SM-42BYG011, 12V, 0.33A) and an LN293 H-bridge. I drive the motor with a 9V alkaline battery. Unfortunately the stepper motor empties the battery very quickly....
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2answers
3k views

Wiring power supply, battery and charger for portable speaker

I'm planning to build myself a small portable speaker. I'd like to include a Li ion battery and a jack for an external 12V-ish power supply. I'd also like to add a jack that will be used to charge the ...
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2answers
59 views

12v 4.8Ah DC regulated to BOTH 5v with 1.9A and 5v 5A

I am in the process of designing a circuit. I am unsure how to design a regulator to power the system. I don't know of a way to be able to achieve what is shown in the diagram above. Looking online ...
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1answer
233 views

Making a low voltage oscillator audible

I am pretty new to EE. I'm trying to make an oscillator similar to this one: In order to run it from a single 5V supply, I've selected a low voltage op-amp (TLV 2324) and am using a resistor divider ...
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3answers
320 views

Cheapest way to limit 4xAA to 5v or less

I need to limit the voltage from AA batteries to 5.25V or less. Essentially, my circuit can operate from (minimum) 3.5V up to 5.25V, and I want to maximize run time by using 4xAA. Should I just run it ...
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1answer
76 views

How can I stop supplying power to a circuit when power drops below a certain threshold?

I'm looking at using a 12V LDO with a 1-2V falloff, so if a vehicle is running the alternator overcomes the 1-2V falloff and the device circuit becomes powered, but I know that I don't know what then ...
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0answers
34 views

Laptop style multi-cell battery charge and power draw

Basically, I'm trying to build a laptop of sorts. Long story... but I want to be able to have the same type of battery setup. I need between 14 and 24V from a multi-cell lipo pack but I want it to act ...
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2answers
515 views

How does the current draw of an IC change with supply voltage?

Suppose I have a device with a number of ICs (microcontroller, logic gates, MEMs sensors, etc) which can operate from a supply voltage in the range of, say, 1.7V to 3.6V. Will the current draw be ...
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2answers
360 views

9v lighter/igniter/heater is not working

Hey guys, I'm new here and I want to make a 9 V lighter/igniter. I used a short nichrome wire from our broken oven toaster, locked it in with two short bolts and hooked it up to a doorbell switch ...
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1answer
53 views

Battery size/type depending on desired usage

Directly below is the overview of a project that has been working well for around three months. A 6 Watt, 12V LED spotlight powered by a 12V 7Ah sealed lead acid battery, controlled by a timer switch ...
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2answers
202 views

Battery setup to power UVC bulb with 12 V DC at 1 A

So, I'm looking to power this UVC bulb kit: The device size overall needs to be pretty small. (I'm trying to mount the bulb in the top of a cup-shaped housing. Ideally, the battery supply would be ...
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1answer
2k views

4.4V vs 3.7V LiPo — Is there such a thing?

I was looking through a very legitimate well known product, noticed the battery pack is stamped with 4.4V. I think this is actually the nominal voltage it provides. The reason I think that is that ...
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2answers
254 views

Won't get 5v on input of Arduino with power bank

I don't know why but i'm not getting 5v on the input of the Arduino, the only thing I've done is to add a switch in order to interrupt the circuit. Here it's my schematic: I have another issue with ...
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2answers
315 views

Three AA batteries in series, only 1 depleted?

I am powering an ESP8266 with 3 rechargable AA batteries. The ESP logs the voltage, so I saw the voltage getting lower over time. Much earlier than expected, the ESP stopped working since the voltage ...
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1answer
41 views

How much energy do Li-Ions/Li-Pos have below 3.2V threshold?

How much energy does a battery still have when a protection chip disconnects it? I know that such discharging kills the battery, but in some cases it would be useful. For example, in drones: when you ...
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1answer
2k views

GSM SIM900A battery power supply circuit

I want to power GSM SIM900A with Lead acid rechargeable battery 12V, 1.2Ah. The voltage regulator I am using is L7805 which gives a regulated output voltage of 4.9 V. My GSM SIM900A modem is My ...
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0answers
2k views

Use the BMS from laptop battery for single cell

I have just disassembled a battery pack from a Lenovo laptop (Series: 45N1005 with six cells, Specs: 10.8V, 5.2Ah, 57Wh) and I would like to use the BMS for controlling a single 18650 cell (2.8Ah) ...
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1answer
79 views

Trouble understanding computer fan wires

I recently found a computer fan in my school electronics lab and I'd like to use it in reverse - make it spin the other way. The trouble is that I can't understand what wire does what, since the color ...
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1answer
100 views

Is there a way to save state in a very low power way?

I basically want to determine if power has been totally disconnected in a low power device I am making that uses an Atmega328 chip. The theory is that when power gets first applied the ATmega will ...
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0answers
119 views

Full time vacuum pump/powered by solar array and battery

I am putting together a vapor extraction system consisting of a small 12 volt (500 mA to 1 A) 6-10 Watt, rotary vane vacuum pump, powered by a solar array with controllers and battery. My goal would ...
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2answers
103 views

Low Power controllers [closed]

As we know that, everything is marketed as Low Power or Ultra low power. I understood that we can classify the controllers based on their application and clock cycle for the above mentioned sections. ...
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1answer
216 views

Trouble with Peltiers TEC and USB Output Current

here is the website I will be referencing: http://www.instructables.com/id/5-Mini-USB-Fridge!/ So I was reading from Inscrutables on powering a small Peltier TEC to cool your hand while reading, and ...
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1answer
27 views

leds and motor on small diarama

Super new to doing electronics projects. I have a project where I have attached 12 led lights in parallel to a small plastic tree. The whole thing rotates on a motor. I am using a 3v CR2450 battery ...
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2answers
3k views

Can you calculate how long it would take to drain a battery given the watts?

I'm looking at an LED light and it says it takes 2.2 watts with a 3.7V / 900 mAh battery. How do I calculate how long the LED light will last if it's on continuously? The item in question is this
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1answer
45 views

Air restriction about batteries

We are building a PCB that we are about to sell for DIY users worldwide (with components). This PCB is microUSB powered, contains a charger chip, and a battery (probably 18650). I heard that there ...
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2answers
84 views

How to turn off a higher supply from a lower one? [closed]

I have a circuit powered by two 12V batteries in series (total of 24V). When switch A is ON, my circuit powers a regulator that outputs 5V to a board I'm using. I'd like to add a second switch (switch ...
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0answers
76 views

Recover battery management system for screwdriver without external power

I used one of many (Battery Management System) BMS on the marker to convert my Ca-Ng battery to Li-ion one. An example: this When bit is stuck or when you want to fixate a drill on drilling position ...
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2answers
132 views

High current power switch required?

I have a solenoid that I need to energize via a 12V car battery. The solenoid will only draw a few amps (2-3?) at the most. Do I require a high current rated power switching contactor (part# ...
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3answers
613 views

Can rechargeable batteries with different mA values be used in the same device with good/normal results?

If I use the two AA batteries (shown below) in a digital camera (where two are needed) will I experience any odd behavior due to the difference in mAh, such as: camera not working properly? battery ...
16
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2answers
35k views

How does this mosquito zapper circuit work?

For the purpose of learning, I have tear down a small mosquito zapper racket. I am now trying to understand how the circuit is working (which goal is to produce high voltage). (yellow = resistor, ...
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2answers
700 views

UPS for home router [duplicate]

Sometimes we have power outages that last about 100 ms that are long enough to discharge capacitors inside router, when that happens we need to wait about 10-15 minutes for DNS, which is pretty ...
4
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1answer
499 views

Beaglebone Black Power Switch Detection

I've looked around and found a bit of information regarding attaching a 3.7V lithium battery to the BBB (Beaglebone Black) but I haven't found an exact answer to what I am looking for. I understand ...
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4answers
1k views

Low voltage cutoff circuit not working

I've spent the past 10 hours trying to figure out why my low voltage cutoff circuit won't work, and I'm at the point where I feel like I need to ask for help. The idea is to slap this circuit in ...
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2answers
62 views

How can I determine run time of a 12V vehicle amplifier using an 18V 5Ah battery [closed]

What specifications do I need to look for in a class D vehicle amplifier so that I can run it for 8 hours using an 18V 5Ah rechargeable tool battery. I need to operate the amplifier at full power for ...
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0answers
399 views

Beginner, how to connect a rechargeable battery to be able to power a 12 Volt Fan and a 5 Volt TEC/Peltier (or 5 Volt Fan/Peltier)?

Firstly, I want to say thank you for looking at my question. I am trying to make something for my nephew, but I really don't have much experience in electronics, even though I have been researching it ...
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2answers
388 views

Do I need undervoltage protection?

I am making a small, handheld device powered by a 9V battery. I am using this regulator and the ATtiny104. My question is, do I need to protect against a low voltage battery? The minimum input for the ...
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1answer
101 views

Using inverter ic to make my circuit switch between USB and Battery power

I am working on a project which will be powered by a single lithium ion cell that is boosted to 5V with a MCP1640 boost IC. It will sometimes be connected via usb, and I would like the circuit to ...
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1answer
54 views

Would the Bluegigga WT12 be suitable for a battery powered application?

I understand that the Bluegigga WT12 requires RS232 when using UART which is what I'm planning to do and thus it requires high voltages? Would that make it unsuitable for a battery powered application?...
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1answer
438 views

Battery Power Management PCB Design [closed]

I am working on an old PCB that uses a lot of the TI IC's for performing its functions. It's essentially a power management board that takes a DC input and charges 12 batteries connected to the ...

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