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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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6
votes
1answer
12k 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 ...
26
votes
3answers
4k views

Why do batteries recover after a load is removed?

I carry a small 2-AA flashlight, and a few times, I have accidentally left it on in my holder. Each time it dies completely, so that no light is emitted, but if I turn it back off and wait for a few ...
6
votes
5answers
12k views

simple, energy efficient circuit to make single IR LED blink

I'm using a 850nm IR LED (spec sheet), and in order to extend my battery life, I'd like to make the LED blink (UF 1.9 V, IF 100 mA). I found a couple of links 1, 2, 3 but they either a) require two ...
3
votes
1answer
2k views

Arduino Battery Over-Discharge Protection (O-DP)

I am getting an Arduino Uno soon, and am planning to run off a 8-cell NiMH battery pack (through the power jack). Assuming a .9V cut-off per cell, that'll mean a 7.2 cut-off voltage. How would I wire ...
1
vote
1answer
2k views

24 Hr A Day Powered Aquatic Pump

I am looking to install a DC 12V 6W submersible aquatic pool pump for use in a small scale hydroponic setup. The location of the beds will be too far away from mains electrical, and I would like to ...
2
votes
3answers
4k views

Implementing a low cost battery backup circuit for internal RTC in STM32F030R8

Extension of this question. Datasheet: http://www.st.com/resource/en/datasheet/stm32f030f4.pdf The micro-controller in question has an internal RTC module but no VBAT pin. As such, the only way RTC ...
2
votes
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 ...
1
vote
2answers
711 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 ...
1
vote
2answers
936 views

Powering circuit directly from USB while charging li-ion battery side by side

What I am thinking of implementing: 1. I have remote monitoring circuit using gsm which senses electrical parameters like phase, power, ac supply etc. Now considering case of no ac supply available ...
2
votes
1answer
1k views

Portable device shielding & ESD

I'm working on a portable battery-powered device with a shielded I/O connector for sensors, but I'm confused about how to properly ground the shield and ESD array. Here is a block diagram of my ...
2
votes
3answers
9k 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 ...
2
votes
3answers
6k 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?
0
votes
3answers
879 views

Batteries and running time

If I have a system working at 2.5V-0.3mA powered by two CR123 3.7V-2000mAh.Is my system going to last the same time if I put my batteries in parallel or in series?Because if I want it to last 12hrs a ...
0
votes
1answer
282 views

Could I replace headphones NIMH battery with Lithium Ion phone battery of the same voltage?

Is it possible to replace a battery for headphones? I would like to replace a 052030 li po battery with a Nokia BL-5C Lithium Ion battery. The li po battery is rated at 130 mAh with 3.7v. The Lithium ...
14
votes
2answers
4k views

LiPo vs. NiMH for kid's toy

I've been researching here and on google regarding potential battery technologies for a toy that I want to make for my kids. I was hoping to get others' perspectives on this, keeping in mind that ...
13
votes
4answers
3k views

Does it matter if a fuse is connected to the negative or positive terminal of a battery?

I am currently going through the conundrum of where to place a fuse in my DC battery-powered circuit to protect the circuit components and the DC battery. I've been googling for a definitive answer, ...
20
votes
7answers
4k views

Why do batteries in consumer electronics get used unevenly?

When changing the batteries of kids toys, remote controls, etc., I test the batteries and have noticed that they drain differently. One will be dead and the other is still in the green. Why does this ...
5
votes
3answers
2k views

Simple, efficient “breathing” LED circuit

I'm currently working on a small circuit, which I intend on running off a CR2032. The intent is to have the circuit last at least 2 weeks (the longer the better), pulsing a green LED every 3 seconds, ...
5
votes
4answers
13k views

Options for getting 3.3v @ 220mA from small batteries

I have a system running at 3.3v requiring 70mA at most times and 220mA at peaks (roughly 20% of the time). I'd like to find a way to power this from coin cell batteries or other small portable source. ...
3
votes
3answers
2k views

Best way to reduce battery consumption for LED device?

I'm building a device that needs to "light up" to indicate status to the user. I of course want to use LEDs to light the device up, but I'm worried about battery consumption since I would like it to ...
2
votes
2answers
4k views

Protect lithium battery in parallel

This question is somehow the continuation of this question : Batteries and running time (reed the comments for more information)And my question is, can I protect my lithium battery in parallel like so ...
0
votes
1answer
1k views

Decoupling a power supply

I'm building my first biped robot, using a Raspberry Pi as the brain. My problem is, I want to decouple the battery before I use it to power the Pi. The reason I want to decouple the battery is ...
0
votes
2answers
11k views

Different capacity batteries in parallel? [closed]

I have two VRLA batteries, 2Ah and 7.2Ah in capacity. Both are 12v. What would happen if I connect them in parallel when they are charged to the same voltage? can I use them to power a 10w LED? what ...
0
votes
1answer
958 views

How to make a discharge curve

I am trying to make a discharge curve for one of my batteries that I have. All I know about it is that it is a 1.5V battery. Now if I have to make a discharge curve for it, how would I make one and ...
-4
votes
2answers
309 views

I want to charge my phone with AAs. How do I get that 5V output with max amperage (Would love to draw that 2.1A)

I was just wondering around, looking for how to charge my phone on the go. Because Wednesday morning I'll go camping. I just don't want to buy a cheap chinese power bank to charge my phone once. And ...
5
votes
1answer
943 views

How does the nRF24L01+ performance degrade with supply voltage?

I'm looking at building a small handheld unit based on an nRF24L01+ in PRX mode. It needs to be able to receive "continuously" to receive control signals that would cause an attached Atmel ATtiny to ...
5
votes
2answers
2k views

Why does this CO detector forbid the use of lithium batteries?

I have several Kidde KN-COB-LP2 CO detectors installed in my house. They look like this: They operate on standard AA-size alkaline batteries, and typically last several years on such batteries. The ...
4
votes
1answer
140 views

Do high and low side labels on bidirectional logic level converters matter?

Logic level converters like this one from Sparkfun have high side and low side labels on them. Now i have an application where I think I need to shift logic levels but the high side and the low side ...
4
votes
1answer
822 views

Battery powered device hardware design tips

I'm working on a prototype product(Wifi motion sensor) that will be powered from a battery source, it has a mega328(arduino bootloader, with sleep mode on and wake on interrupt,and WDT in case it ...
3
votes
1answer
1k views

nRF24L01+ RX in pulsed operation to save power?

I'm considering building a handheld radio receiver based on an nRF24L01+ and an ATtiny chip. It needs to receive "continuously", to receive a control signal that might operate some attached LEDs or ...
1
vote
1answer
164 views

Spec'ing an always-on alarm/tracker for a car battery

What is the specification of a standard car battery (e.g. of a 2008 Jetta)? Say, I want to connect an always-on alarm or a tracker to the electrical system of the car. Is it likely to deplete the ...
1
vote
1answer
753 views

How does a bad power factor affect batteries with inverters?

Let's say I'm using a 100% efficient battery (AC battery, so there's an inverter in front of it) to power a motor with a power factor of 0.5. Let's also assume the inverter cannot correct the power ...
1
vote
1answer
2k views

Switching Arduino/ATMega to sleep mode when on battery

I'm trying to make a small clock but want to ditch the need for a separate RTC chip with battery backup. What I would like to do, instead, is keep track of the time completely on the ATMega using the ...
1
vote
3answers
2k views

2xAAA battery => 3.3v/250mA step-up converter with logic-driven power control [superseded]

EDIT: The requirements in the question below appear to be practically unsolvable, but happily after a bit of digging I actually found an alternative equivalent RS232 device which runs off a 3.7V Li-Po ...
0
votes
0answers
61 views

Motor driver powered by PSU instead of battery [duplicate]

I am about to use a motor driver in a project (MDDS30 by Cytron) and I was going to power it using a 12v 11.5a PSU. I discovered that the manufacturer warns against using a PSU, and that it might ...
0
votes
2answers
75 views

SLA battery constantly being charged and used

I have a 12V 7Ah SLA battery with a smart battery charger for SLA batteries with the maximal output of 0.8A. I would like to use the battery to charge an Arduino board with few other things (at most ...
0
votes
1answer
648 views

Really loud, yet compact, long(-ish) duration, battery operated — hooter / siren

Is it possible to design a small / compact, hand-held siren (i.e. with a loud hooter), that is battery powered and fits into something like a 3"x3"x2" box ? The requirements in more detail: Hooter ...
0
votes
3answers
361 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 ...
0
votes
2answers
279 views

Controlling a LDO with voltage detector

For one of my project I need to shutdown my system when my Li-ion battery reaches 3V.But I want to know if I can use this type of component : http://www.farnell.com/datasheets/11601.pdfhttp://www....
0
votes
1answer
207 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 ...
0
votes
2answers
433 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 (with ...
0
votes
1answer
2k views

Battery powered light curtain of 100-150 LEDs

I have a hobby project of putting together a light curtain of 100-150 LEDs (3V, 20mA). It is meant to be used in an event outdoors without mains power. It could be operated with bunch of ordinary ...
0
votes
1answer
251 views

Parallel lipo batteries with mcp73831 charger IC

After reading this very informative blog about load sharing while charging batteries, I'm planning on using an MCP73831 in the same configuration as detailed by the blog for use in a project I'm ...
-2
votes
1answer
90 views

Battery Run-time/capacity calculation

Problem is to find the difference in run-time between: a. Using 12V 10Ah battery vs 24V 5Ah battery. PS: Load is rated at 12VDC and 24V to 12V step-down conversion is available.
-5
votes
1answer
283 views

Battery capacity calculation/method [closed]

While calculating battery power capacity requirement for a circuit consisting of multiple loads having different power consumption, how should one proceed to avoid any error? How it is done in ...