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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3answers
48 views

Measuring state of charge of a non rechargeable CR123A lithium battery

Is there a method (voltage, resistance, other...) of measuring leftover charge in a non rechargeable lithium battery? Background: I'm trying to get a general overview of power consumption for few ...
0
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0answers
50 views

What is more power efficient: GPRS or SMS for a GSM sim Arduino application?

I have a GSM shield for my Arduino and am wondering the most power efficient way to receive and send data from and to the cloud. The specific project I am looking to accomplish is starting my car ...
1
vote
1answer
45 views

Power switching peripherial parts by MCU

Using an MCU like from MSP430 series, it is possible to create circuits that runs from battery power for years in some standby mode (waiting for button or realtime clock alarm for example). However, ...
0
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1answer
124 views

Arduino and GSM Module running on Li-primary batteries for years

For one of our projects we need to run an Arduino board + GSM module (SIM800C for example) for many years on batteries without recharging. The Arduino should be in power down mode for 99,99% of the ...
14
votes
3answers
2k views

Lithium Coin Cell CR2032 battery specifications

I am using a CR2032 battery module to operate a BLE 4.1 module. The BLE radio for communication takes around 3.5ma to 5ma of current. But when I look at the datasheet of the battery ...
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0answers
65 views

How to connect these two led strings?

I've recently bought myself 2 sets of leds. Each set has 10 leds in a row powered by a solar panel which charges 2x 1.2V batteries. My question is what do I have to do when I want to have all of the ...
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1answer
40 views

Float charge heat dissipation of battery [closed]

I have a lead acid battery with specifications shown below. I wish to calculate the power & energy required to charge the battery from fully discharged. Constant current discharge (amperes) at ...
3
votes
1answer
88 views

How long should 8, 1.5V batteries last for?

I purchased a GPS tracker from Amazon and instead of wiring it to the car battery I would like to simply attach my own power battery pack. I am a complete noob when it comes to electronics and I ...
1
vote
1answer
224 views

What is the meaning of 25C?

I have a lipo battery of 11.1V,3s,5200mAH. What is the meaning of the 25C discharge current? How much current does it indicate? How do you interpret it?
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2answers
66 views

LDO regulator below minimum input voltage

I'm designing a circuit that will run from 3V battery. The battery can get as low as 2V and I want to use it as much as I can. I'm using a PIC24 that operates with the integrated regulator for ...
0
votes
1answer
27 views

5v usb cable to power a 2AA Kitchen Scale [closed]

This is my first question and I'm a total beginner at this, so, please be kind :D I have a kitchen scale that eats up 2AA batteries every 2-3 days, so I thought to power it via a USB wall charger ...
3
votes
3answers
100 views

How to efficiently power wireless sensor node from a 9V battery?

Context I have recently set out to add some wireless features to my entry-level smoke detector. Problem In order to achieve that, I will be adding a custom pcb embedding an ATmega328P and a ...
0
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1answer
101 views

Does a motor really need all this circuit to run?

This is the pcb of an Ikea screwdriver, you can see I desoldered the 18650 battery, from B+ and B-, and desoldered the motor from the legs of the switch which is on the other side. So the circuit ...
1
vote
1answer
97 views

How to charge a lipo battery inline with load

How do you charge a lipo battery while it's still connected to it's load (e.g. like all modern mobile consumer electronics) using an off the shelf lipo charger? I have an Accucell S60 battery charger ...
1
vote
0answers
40 views

ESP8266 servo controler

I am building a small application, that should be able to connect over wifi to server, pull some data and turn a connected servo accord the result. The system should be powered on battery. Is this ...
0
votes
1answer
61 views

Powering 5v LEDs with 6 or 12 volt batteries

I'm building an art piece that uses about 2000 RGB LEDs. They are WS 2812b LEDs, and I expect the normal draw to be around 200-300 watts. If all bulbs go full white at the same time, it could pull up ...
0
votes
1answer
54 views

2 Blue LEDS , in series or parallel/ optimal power resistor type of batteries compact area

I intend on making a project illuminating an acrylic transparent rod. drill holes on both sides and inserting Blue LEDS tight space wired in series or parallel what resistor value and perhaps small ...
0
votes
1answer
73 views

how to differentiate the gnd audio to gnd of battery?

i'm new to the forum. I have some problem to Connect this device with one single battery. I think the problem is on the connection of the max4466 electret. It has a common ground and it make me ...
0
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2answers
153 views

Car stereo wired to computer power supply with backup battery to keep memory

This past Christmas I re-purposed an old Car Stereo and built a portable outdoor radio for my Dad. Ultimately what I wanted to do is have it to where it runs primarily off of a computer power supply ...
0
votes
2answers
63 views

How to Power a Controller and Motor Driver off same 24V source

I am trying to find the optimum electrical design for my project. The project is a remote control vehicle that is moved by 2 DC motors, controlled by an arduino MC and powered by 2 X 12V 4Ah ...
3
votes
3answers
82 views

How to determine whether I need ESD protection? (MOSFET H-Bridge)

I am designing a H-Bridge using IRLZ44N MOSFETs, IR2104 driver ICs and UF5401 diodes. The current circuit looks like this: It will be used on a battery powered device, so no real grounding ...
3
votes
2answers
66 views

Powering a sensor with a battery

Basically I'd like to deploy a sensor temporarily for a period of about a month. The sensor communicates via a wireless protocol and sends a data packet about once every 5 minutes as far as I ...
1
vote
2answers
105 views

Can solar panel charging slow down the draining of phone battery? [closed]

I have made a solar panel charger, it consists of a 1.2 watt panel connected to a buck converter, then to the phone. Now, when I connect it, it charges the phone and in the battery settings it shows ...
3
votes
2answers
103 views

Portable 5v power supply to duplicate wall wart

I've got a wifi device that works off of a 5v 2a wall wart. I need to walk around with it to get some signal strength ratings, so I am making it a portable power supply. However, the device won't ...
0
votes
1answer
40 views

Dealing with different voltage needs on a battery driven low-power board

I'm going to design a small wireless sensor box for a weather station project. This involves: A sensor running at 3.0-3.6V (1mA) A MCU, running at 3.0-5.5V A 433MHz transmitter which takes about ...
0
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2answers
52 views

How to determine the Solar-panel power requirement battery

I'm having a problem calculating the rated power requirement for my solar panel project. The panel will charge a battery that will power a 'micro' water pump. The power requirement for the pump is ...
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vote
2answers
141 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 ...
0
votes
1answer
41 views

suggestions for solar charging battery-operated device

My battery-powered wireless device draws about 50mA @ 5V. I’m thinking of powering this off a 12V 7Ah SLA battery that is topped up with a small solar panel (12V, maybe 500mA or so). 12V to 5V will ...
0
votes
1answer
46 views

What AC-to-DC adapter would I need to power two of these battery (3V) powered door contacts at once?

I'm new to electrical wiring. I understand circuits, soldering, and basic wiring in parallel / series but calculating and understanding draw, resistance, etc. is new to me. That being said, I have ...
0
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3answers
100 views

Car battery capacity in colder countries

The capacity of the battery is affected when the temperature drops, particularly Lead-acid batteries. So how in cold countries this situation is solved. In this PDF about automotive batteries at low ...
4
votes
1answer
186 views

Coin Cell Battery Safety?

I'm working on a wearable project that is really space constrained. Originally, I had planned to use a Li-Ion battery, but I opted out of it because the person wearing it won't be able to take the ...
0
votes
2answers
78 views

Bike mobile charger

Hi, I've made a battery operated mobile charger using this circuit. I am able to charge the basic phones (with 2100mAh battery) with it. But the problem is, I couldn't charge any smart phones ...
0
votes
1answer
69 views

LM2940CT-12 output measuring 9.6V when relay used

So I've got a 12V pump, and a car battery, and I'm trying to regulate the 12-14V from the car battery to 12V output. When using just the LM2940CT-12, it outputs 12V on the dot. But when I use an ...
0
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2answers
74 views

3V7 to 5V level conversion

In my product i am using a wifi module requires 3.3v and a bunch of other components requires 5v. For this i am using 3.7v 3000mAh battery. So here i have a doubt whether to use which case or any ...
1
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3answers
301 views

Area under voltage vs time discharge curve

Will the area under a voltage vs. time graph of a battery discharge curve (with a constant current load) give the amp-hour capacity rating of the battery? Thank you.
0
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1answer
65 views

Converting 3 seperate 4.5V battery operated devices to one AC power supply

I'm wanting to convert 3 battery operated marquee signs to AC power by following one of the many tutorials out there on sites like instructables.com. I'm more than capable of doing each one on its ...
0
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1answer
139 views

Selecting a battery for a DIY project

I am building myself a laptop (for fun, I know it doesn't make economical sense ;) ). I have now come to the problem of implementing a lithium battery for it. It will have to power the SBC and the ...
0
votes
2answers
45 views

How long will my circuit run normally if its battery level reduces? [closed]

I am using a 3.7V battery for my circuit. What will happen when the battery level reduces to 3V, 2.5V, etc? Won't some of my components stop working at these low voltages?
0
votes
2answers
72 views

Can you connect in series 2 unequally charged batteries?

So I have 4 batteries. 2 of them are charged (about 70%) and 2 about 10%. I have a flashlight (which uses 2 batteries in series) which I would like to power at small current and voltage because the ...
2
votes
2answers
85 views

OLED is garbled when powered by 3.7 battery but not when powered by USB or variable regulated power source?

I have an esp8266 on a breakout board for programming hooked up to an OLED via GPIO 0 and 2. It works fine if I power it via the FTDI/USB. It also works when I power it at 2.8-3.0V using a desktop ...
0
votes
1answer
128 views

3.8V batteries to 5V

So I got me a raspberry pi 2, and a R2FX, both supplied with 5V, R2FX has a power consumpution of less than 1W. I own several accumulators from old phones & smartphones which got 3.8V . Maybe a ...
1
vote
4answers
560 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 ...
2
votes
1answer
244 views

Battery and Voltage Regulator for ESP8266 and HC-SR04

I'm working on a project that includes an ESP8266 (requires 3.3v input (250 mA peak)) and a HC-SR04 (requires 5v 20 mA peak). I'm making it battery/solar powered. I'm trying to keep costs down as ...
2
votes
5answers
150 views

Fan Needs 12V, only have 9V

I recently bought a 12V small computer fan(about 1"X1") and it was running rather slow when I checked it with a 9V. The package says that the fan requires 12V to run at an optimized speed, so is there ...
0
votes
1answer
88 views

How to create a system where battery power exist as backup power source

This mainly applies to design of a clock but can be applied to many other circuits. The idea is that a device with PIC microcontroller is usually powered via external DC power supply which obviously ...
2
votes
1answer
141 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 ...
5
votes
2answers
80 views

Efficiently sensing the voltage of a battery pack

I'm looking to sense the voltage of a battery pack that is powering a device by the device. Depending the the level of the pack (2 cell LiPo 1200mAh) the device will change it's behavior. As the pack ...
0
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1answer
418 views

Charging 12V Battery from AC-DC Converter

I am planning to charge my 12V sealed Lead Acid battery from AC to DC Converter. The output of the AC-DC Converter is adjustable so that I can set my voltage to be 14.7V(considering diode voltage ...
2
votes
3answers
331 views

Powering NiChrome wire from battery

I'm looking to power nichrome wire from battery. The problem I ran into is that desired length/width of the wire has very small resistance ~ 8 Ohm. Several kinds of batteries I've tested have ...
0
votes
1answer
336 views

How to measure Open Circuit Voltage of a Battery in Charging and Discharging state

I am working on a battery(Li-ion) operated device, in my attempt to get the SOC of the battery i have to acquire the battery OCV (open circuit voltage) first and have to interpolate it to the SOC ...