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Questions tagged [batteries]

An electric battery is a device consisting of one or more electrochemical cells that convert stored chemical energy into electrical energy

12
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3answers
18k views

How can a car battery be charged by dynamo (or is it an alternator?) at the same time it is being used by the car components?

note and question * Is it an alternator or dynamo? I am not an electrical engineer and neither have any core knowledge but, this is a simple procedure of car ...
6
votes
2answers
1k views

What to consider when choosing batteries for a project?

How do you choose what batteries to use for your projects? Are there a set of criteria that they need to be able to do in order for you to consider them? If so what are they?. The only 2 that come to ...
17
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6answers
42k views

Combining and Charging multiple Lithium Ion Battery Cells (3.6 V or 3.7 Volts)

1] Voltage: 3.6V or 3.7V Are all 18650 lithium ion battery cells 3.6 or 3.7 voltsor or are there different voltage Lithium Ion cells in the market as well? 2] Possible Voltage Shortage? Do all 3.6/3....
10
votes
1answer
3k views

Why do battery/power supply supply voltages drop under a load?

Why is it when you connect a battery to a heavy load does the voltage coming out of the supply drop?
10
votes
2answers
748 views

Do batteries last longer with constant current draw or spiky current draw?

Do batteries last longer with constant current draw or spiky current draw? Or, as is implied by the accepted answer to "Making a battery last a long time in a microcontroller circuit", do some ...
7
votes
1answer
2k views

How to recharge a battery with a manual battery charger

What are the best practices for recharging a 12V lead acid battery with a manual recharger. I have a 12V lead acid battery (7.2AH/20HR MK ES7-12 (PDF)). I've read the advice here on how to check the ...
5
votes
4answers
1k views

is the resistance in ten meters of copper wire too high to use in a circuit powered by AA batteries?

I have a wireless security system at home, and the wireless node is too far from the receiver. I was thinking that I could splice about 10 extra meters of wire into the existing line to move the node ...
6
votes
3answers
354 views

What type of battery to use?

I Am currently looking for battery suggestions for use in one of my projects. My projects current consumption (calculated) is 360mA for the main rotor 2.5A stall Link (my exact part RK370SD-4045) ...
5
votes
5answers
1k views

Will these LEDs work for throwies?

I'm going to try to build some throwies soon and am ordering some LEDs and other needed things for the task. It is my understanding that a CR2032 battery is 2.6-3.1 volts. Well, I have these LEDs ...
24
votes
3answers
13k views

Does leaving a cell phone on charge all the time weaken the battery, and why?

If I leave my cell phone with the charger plugged in all the time, would this weaken the batter, and why? I've heard that you should only charge the cell phone when you receive a 'battery low' message ...
1
vote
1answer
365 views

Could my Cell Phone Battery be degrading? [closed]

I've noticed that if I recharge my cell phone battery to 100%, then take it out, and put it back in and put the phone back on charging, it resumes charging the battery and continues to do this for ...
3
votes
2answers
7k views

How to correctly store spare Cell Phone Battery?

I've got a spare battery for my cell phone. I'm wondering what the correct way to store it would be, so as to maximize the battery time. Should I recharge the battery to 100%, then leave it aside, or ...
8
votes
4answers
33k views

Can I break batteries by putting them in the wrong way?

If I put in batteries the wrong way (+ and - sides reversed), is there a risk that I will break them? Or the device? Or start a fire? In particular, I am talking about rechargeable Ni-MH eneloops ...
2
votes
2answers
2k views

Can I drop 4.5 V to 3.7 V with a diode?

I have an RC helicopter with a dead 250 mAh lipoly battery with a voltage of 3.7 V. Could I use 3 button cells at 4.5 V and a diode with 0.7 voltage drop to power the circuit, which is somewhat ...
5
votes
4answers
5k views

Will there be any voltage drop when connecting load to batteries?

In my project I am planning on using 10 AAA Batteries(to give me 12v as each battery is 1.2v) to power my project. I am wondering if there will be any voltage drop when I connect a load. If so how can ...
5
votes
2answers
546 views

Solar powered water fountain

I am planning of building a solar water fountain which would serve as a bird bath in my backyard this summer. My requirements are simple: The fountain should be powered by solar energy, a small ...
8
votes
2answers
4k views

using an op amp in a battery powered circuit

I'd like to use a simple non-inverting amp circuit in a small project I am working on. The project is battery powered, so naturally the only voltage I have access to is 3.3v. My question is: how ...
6
votes
3answers
4k views

What are the standard connectors used on 12V hobby batteries?

I'm looking for a right-angle PCB board mate for the standard 12V hobby battery connectors. Where can I find these connectors?
5
votes
4answers
19k views

Building a Battery Charger with an LM317

I was told that i could make a simple battery charger from a LM317 and a resistor to charge some Ni-MH Batteries. Can someone just expand on this a little such as how it works as I don't really ...
3
votes
1answer
532 views

How can I build a solar powered car charger?

I found 12 solar panels, but they are very thin and fragile. They put out approximately .5V under an incandescent bulb. What would be the best way to turn these 12 panels into a 12V car battery ...
5
votes
3answers
269 views

Is it safe to recharge a battery without a specific device?

I have 9V Li-ion battery. If I apply regulated 9V to it, will it recharge? What about other kinds of rechargeable batteries?
0
votes
5answers
301 views

What's the name of the device I'm looking for

I'm looking for a device which monitors a 3.3V line. When the line drops below, say, 2.7V, I would like it to switch power over to a battery backup (3V lithium coin cell.) It would also be good if it ...
36
votes
5answers
9k views

Are decoupling capacitors needed with battery power?

Currently I run all my gadgets from batteries and don't use decoupling capacitors. Are they generally needed/useful when drawing energy from a battery?
27
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3answers
15k views

Are coin cells a suitable replacement for AA batteries?

I am currently using AA batteries in my projects but would like to look at cell batteries for my next project, due to their compactness. Apart from the physical appearance, how do cell batteries ...
19
votes
4answers
2k views

Supercap compared to a battery

What is the current state of things when it comes to super capacitors and batteries? Are super caps anywhere near rivalling LiPo's in capacity? I've often heard people talking about super caps as ...
10
votes
2answers
12k views

Internal resistance of batteries?

In one of the answers on this site, I found link to this project. That article mentions internal resistance of batteries and cells. Where can I find data about common ranges of internal resistances ...
7
votes
3answers
21k views

Battery level - how to check

How can I check the level of charge left in a battery?
3
votes
2answers
208 views

Resurrecting a 12V SLA from a UPS

Got an old 12V UPS battery, a sealed lead acid 17.2Ah battery. Quite a nice YUASA battery. Unfortunately it reads 9.92V so has been discharged badly. Is there any chance of salvaging it?
3
votes
3answers
3k views

Mobile phone battery charger

I would like to know about the workings of mobile phone battery chargers. I know the basic principle, you take a transformer to bring it down to 9/6/3.7 volts then a bridge rectifier circuit and a ...
4
votes
2answers
615 views

Best Circuit Design for a 12VDC Wall-Wart > Ouput Voltage of 1.5V (Replacing Alkaline Batteries)

I have multiple stationary baby items for my son Oliver that require a serious supply of batteries each month. I would like to hook a few of these stationary items up to wall warts to conserve the ...
14
votes
7answers
5k views

LEDs on a (battery) budget! – How can I lower the current through a LED without using up the battery?

EDIT: Here is a much brief version, the meandering motivated version is probably subsumed in the parent question on general battery life optimizations. How can I lower the current into a LED ...
25
votes
5answers
5k views

Making a battery last a long time in a microcontroller circuit

I'm hoping to power an ATtiny85V for a nice long time on some small battery, probably a coin cell. I've looked into the software side, and my code is watchdog timer driven, has unused analog and ...
1
vote
3answers
895 views

Ipad charging via usb port

Ipad doesn't charge while in use and connected to the usb port. It definitely charges when connected to the supplied 10 watt power adapter. The USB port, as far as I know, supplies 5 watts. Can we ...
13
votes
4answers
10k views

What are the basics of making a rechargeable battery pack?

We have a device that runs off of a AC adapter, or a pack of 8 AA batteries. Since in normal use we use both, it would seem to make sense to have the battery pack recharge while using the AC adapter - ...
4
votes
1answer
98 views

Are the specs for the “Ears of the World” challenge reasonable?

I saw a post today on the Make blog about a challenge to create an extremely cheap FM/SW radio kit for developing nations. The organization sponsoring the challenge distributes donated wind-up powered ...
7
votes
7answers
6k views

Dummy battery shells

I have a device that takes two AA batteries and I want to replace it with my own external power source and regulation circuitry. Instead of clipping or soldering wires to the device contacts, I would ...
8
votes
3answers
8k views

How do I design a device to automatically switch to the backup battery?

I've been told that many kinds of batteries work best if they are used until they are completely drained, and then recharged. (Edit: The "memory effect myth" is quite widespread. Batteries work just ...
3
votes
1answer
1k views

Arduino Battery Shield

I'm looking for a battery shield for my Arduino Duemilanove. I would be asking "what's the best" but everything I find is out of stock except for this: https://www.liquidware.com/shop/show/BP/Lithium+...
5
votes
3answers
207 views

Close enough for voltages?

I want to extend the use of a camera. The camera currently uses a special li-ion 3.7V 1000 mAh battery. I could grab a couple of those batteries, wire them up in parallel, and that'd work just fine. ...
1
vote
2answers
1k views

Low Voltage Shunt Regulator

Hey, I came across this Low Volatage Shunt regulator on a Hobby RC forum, I am trying to figure out how the resistor Values are Calculated, http://www.rcgroups.com/forums/attachment.php?attachmentid=...
6
votes
3answers
2k views

Small batteries for use in cold (but not freezing) environments?

I'm building a small, low-power device that will be used inside a standard consumer refrigerator (approximately 2°C). I've had trouble with Alkaline batteries at low temperatures, and was wondering ...
10
votes
5answers
5k views

Battery life monitor on PIC circuit

I have a small circuit using a PIC18F14F50 microcontroller chip which is logging data into an external EEPROM chip over an i2c interface (which I can then read back later over the USB interface). One ...
16
votes
5answers
31k views

How do I connect two identical batteries to increase the consumer lifetime?

If I've got a device that uses a single battery, and with that single battery, the device lasts an hour, and I want the device to last for two hours, I'm assuming I can wire two batteries up and it ...
17
votes
4answers
6k views

How can I tell how much juice a LiPo battery still has in it?

Suppose I have a circuit that draws its power from a LiPo Battery. I would like to know how much power the battery still has in it. Ideally a circuit of power level to voltage will be best .. this way ...
29
votes
8answers
41k views

Current flow in batteries?

I am reading a basic electronics book: "There are no Electrons: Electronics for Earthlings" and I came across a clever passage about the fact that you need a closed circuit in order for current to ...
11
votes
6answers
6k views

Inductive Charging

I've build a small three wheel robot with an Arduino Mega to drive the thing. I'm looking to keep this bot mobile as much as I can without needing to interact with it for charging etc. For the moment ...
2
votes
3answers
230 views

How to I determine/ interpret values of autoranging multimter

I have an autoranging multimeter and many AA batteries.... how do I interpret the readings when deciding to keep or discard AA (1.5 volt) batteries?
8
votes
5answers
4k views

Cold weather battery power

I've built a temperature sensor module that runs off of 4xAA batteries and sends data back to a computer via XBee. Works great, until the weather gets cold. At that point, the rechargeable AA ...
17
votes
2answers
3k views

How might you use a LiPo battery as backup for mains power loss?

Many people seem to run their projects off the mains (e.g. with a wall wart) or from a battery, but there doesn't seem to be too much discussion about how to run a device off the mains, charging a ...
9
votes
2answers
394 views

Batteries for 12- to 24-V motors

I have some nice gear motors that run on 12 to 24 volts, and want to use them in a medium-sized mobile robot -- maybe 30 cm * 30 cm for the base. I only expect it to run indoors, or possibly outside ...