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battery life

Any one know about how long 4 double a's wired in series will last with a 200 milliamp load, here is what the online LED calculator said, I'm working on putting this in a small flashlight:Solution 0: 1 x 2 array uses 2 LEDs exactly +----|>|---/\/\/----+ R = 27 ohms +----|>|---/\/\/----+ R = 27 ohmsThe wizard says: In solution 0: each 27 ohm resistor dissipates 270 mW the wizard says the color code for 27 is red violet black the wizard thinks ½W resistors are needed for your application together, all resistors dissipate 540 mW together, the diodes dissipate 700 mW total power dissipated by the array is 1240 mW the array draws current of 200 mA from the source.-thanks

Topic by firemanfu    |  last reply

Battery Charging? Answered

If i charge a battery when it's half full will ruin the battery life between charges?

Question by KnexFreak360    |  last reply

Extend ipod battery life?

Would it be possible/feasible to buy a replacement ipod battery, open up the ipod, and solder the battery in parallel to increase the battery life? Or is the new ipod too thin to do that?

Question by 7654321    |  last reply

Battery life indicator for 1.5V battery source

Hi guys, I want to make a simple battery life indicator for a device running from a 1.5V battery source. I would just need a red/green LED to light when the Voltage is above a certain limit (say 1.2 V). and to turn off once the limit is reached.. Is there any simple circuit that enables me to do this?

Topic by kurtselva    |  last reply


Hi, I'm building a mini BB-8 unit for a project and going to make many more for a club. My biggest problem I'm encountering now is the battery needed to power it. The entire circuit draws around 500mAh and runs  on 3-5V. I don't think a 9V battery is enough to power it or even a AA battery no matter how many i put on it. The online guides that I found uses 18650 batteries either salvaged or bought. However, from where I come its very expensive to buy this batteries and it the charger cost even more. So I was thinking of buying this cheap 2400mAh powerbank that is sold commonly here. It outputs 5 volts and can be charged by USB. This powerbank cost about the same price of a 9V battery but only have life span of about 2 months which is good enough in my opinion. My main question is are there any other alternatives to power this circuit at a cheap price and is it possible to use a powerbank to power this circuit? Tq for any help and suggestions.

Topic by KhayhenS  

Is it possible to put batteries in parallel to increase battery life?

I was just wondering if it is possible to put batteries in parallel to increase battery life? I was thinking of the Go Pro Hero 3 camera. I know they have a battery backpack, but I just wanted to know if it was possible to stretch the battery life, if you bought lots of batteries and put them in parallel.... And attach the pack of batteries with a cord. Or is there another way to do the same thing?

Question by bethekind  

Battery conversion? Answered

I have a rc helicopter and the controler uses 6X aa batterys. I thought that it would be cheaper to use a 9 volt battery instead. Would it damage my remote? Also Would this affect battery life and if so by how much?

Question by David97    |  last reply

would charging a battery with a motor reduce the battery's life span?

I know that charging and discharging a battery is what "drains it's life" because it holds less and less of a charge each cycle, but is it the amount of charging and discharging, or just the number of times it's being charged or discharged?

Question by the judge    |  last reply

New battery for laser need to extend life.?

I just bought a nice red 200mw laser. I had it for 2 days and its already lost its burning power :( it has 2 CR2 3V 1000mAh batteries and they run out fast! Can i attach one of those lantern batteries that add up to 6 volts and jerry rig it to run on that. Will that increase life without burning out my laser?

Question by conrad2468    |  last reply

how to increase 12v, 45A battery life.

How can i increase the life spam or strength of a 12v 45A battery 

Question by agasco    |  last reply


Hi i am working on a project were i have a power source, a resistor, then an using a resistor and limiting the power to the LED will that make the life of my battery longer? any help would be greatly appreciated, thnx :-)

Question by ShOoP dUh WoOp    |  last reply

Do we know the battery life of the CR2032?

According to this CR2032 data sheet at 3 volts left continuously on, the battery would last 1200 hours. (If I'm reading this right) Should we worry about having to change out the battery every couple of months?

Question by DELETED_MakiY2    |  last reply

Li-ion battery

Whats the best way to reclaim some of my lost battery life from my laptop? Or is it imposable?

Topic by steven07    |  last reply

Would this idea to prolong battery life work? (NOT perpetual motion, just extended life!) Answered

A few days ago, I designed a self-charging battery system using a dc motor attached to a rechargeable battery pack that turns a generator via gears, similar to how a car battery works, converting kinetic energy from the motor to electrical energy with the generator and looping back to the battery. I've modified the idea to reduce friction as much as I can so that the motor and generator are directly attached now, keeping energy from being lost to friction between gears. Here's a crappy diagram:    |-----|--------------|                     |--------------|-----|    |       |  Motor       |-------||-------|Generator|      |    | | ---|--------------|                     |--------------|---| |    | |------------|----------------|------------------------| |    |--------------|  Battery      |--------------------------|                       |----------------| I know that 100% efficiency is impossible, I'm not trying to get all the energy back, and I'm not trying to create energy. I'm trying to loop the energy that isn't lost to friction and other factors back to the battery, hypothetically charging the battery up a little to somewhat extend the life. I realize that it will eventually go dead no matter what I do due to the laws of thermodynamics. What I want to know if this would increase the battery life enough to be worth incorporating in a design. (I know the motors should be attached to the battery by two different ends but its actually supposed to be a rechargeable battery pack so one motor is attached to input in to charge the battery and the other is output so the battery powers it. Plus if I tried to draw the wires like that it would've taken forever.)

Question by ALogan97    |  last reply

Battery memory effect: a thing of the past?

Do I have to let my batteries run out before recharging? Why cell phones seems to have unlimited battery life cycle and some others things don't? What about my iPhone? It would be great to charge it a little bit every time I'm at any computer but I have this kinda fear to riun it's battery life...

Question by lowercase    |  last reply

can i make battery life indicator that tells whether the battery is low?

The battery indicator is like in the cellphone; where you can tell that ur phone needs to charge.

Question by vestro    |  last reply

coin cell battery

Question about flashing red LED: I have a simple circuit--switch, battery, resistor, LED. Today, when I clicked the switch on, the LED came to life very slowly, as of it were fading in. I have never seen this behavior before. Is it the battery? (3V, 2032 coin cell and 100ohm resistor). Thanks.

Topic by yongeeks    |  last reply

Battery life indicator for Arduino powered fish feeder

Hi all, So I am basically a noob in electronics and a 1st time arduino user for my project. I need to do an automatic fish feeder and this is what I have in mind: I'm gonna use an arduino UNO R3 to connect it to these following components: - a 16 x 2 LCD Display (connected to RTC chip) - a small DC motor - 2 pushbuttons So these are the main components and I need the arduino to be portable ( So has to be battery powered - Maybe a 9V batt) As such I have 2 questions: 1) Is it possible for ALL the components to run using power from arduino? 2) I need to add a battery life indicator as well.. how do I go abt doing it? Hope you guys could help me

Topic by kurtselva    |  last reply

keeping batteries warm?

We have 12v batteries to support our solar power.  our problem is keeping them warm when we are not at home.  does anyone have any suggestions?  we are often gone for work for 3 - 5 weeks, so we can't do wood or waste oil, and days without sun wont help our batteries.  this year it is very cold, night time wind chills below -10

Question by mag1213    |  last reply

New life for an IR keyboard?

So i have an old Palm infrared keyboard that works with two AAA batteries and i was thinking, what's the easiest approach to use it with my Nexus 7?, somehow re-wire it to USB? Use an arduino as a bridge in some way? An IR sensor adapter for the nexus and some software i don't know? any suggestions, or someone wants to give it a try? Oh BTW hi! i'm a noob on the forums but i love the site.

Topic by jcarlos10    |  last reply

do disposable camera's run out of battery? Answered

 I've recently made a taser out of a disposable camera and was wondering does the camera run out of charge over time? or does the charge get less or something?

Question by pete54321    |  last reply

How long with this power a led

I have an idea for a nightlight for kids or even adults in the hallway or something.  But I am running into a problem.  The main housing for this light is going to be pretty small.  I was first planing on running this off a household electrical plug and that would work best.  But I would not know quite how to step down the power from the wall to only run 2-3 led lights.  I am sure I could get some sort of small circuit board that would drop the current.  However because of the small housing I doubt I could fit that in there.  I know I am not giving a whole lot of details but I do not want to give away my idea quite yet.  What I am wondering is how long would say 1 AA battery run 3 LED lights?  I am thinking this idea is not going to work out because people are not going to want to have to replace there battery every week or even more.  So if anyone has some input on this idea then please let me know.  The housing I think I would have to work with would be something like a pipe that is maybe 1 inch across the opening by about 2 -3 inches long.  So nut much room to work with at all. I await your replies.

Topic by jcaresheets    |  last reply

Battery provides a constant potential difference all along its life time? Answered

Will a 12 Volt battery provide the same potential difference of 12 Volt even after using it for long time? Or it will decrease from 12 v to 11.5 and then 11.1v  and then to 10 v ...................5v.............3v.................0.5v,0.1v and then at last 0v with usage? Give reason if it works as constant source of potential difference supplying agent.

Question by deepakmurali    |  last reply

Life Size Operation Game

I am making a life sized operation game for a fund raising event in my village. You know the kids game where you have to removed plastic bones from a flat cardboard patient without making the buzzer sound or making his nose flash? I am fine on making the game but am in need of help re the electronics. I want to make it so that if the person handling the tweezers closes the circuit the nose flashes for two or three seconds before swirching off, and also at the same time I want the buzzer to sound for two or three seconds before switching itself off. Can anyone please help re this? I need a circuit diagram that will do this. I intend to power the project with batteries. Thak You in advance. Jonesy

Topic by batjonesy    |  last reply

Lead Acid battery repair?

I have a dead  6  volt 4ah   lead acid battery and 12 v 190 amp  liquid  battery some one help me to bring it back to life 12 v battery i used with ups

Question by chnaveed.alam    |  last reply

how much time will it last ,a throwie of 10mm with a battery of 3v?

How many hours or days will the led be "ON"? using a 10mm led with a 3v battery

Question    |  last reply

Batteries and LED light modules - correctly powering for maximum life

Hiya, I need to power a LED strip of 3 LED lights with batteries. The LED box says it is a 12VDC light module, and on the back of the box it says the Input Power is 0.0453A. My limited understanding is that I should use a 9V battery plus 2x AA battery (I have limited space - a 8 AA pack wont fit inside my project) that correct? I need to know how long these batteries will last - if it is less than 10 hours can you suggest another way of powering it? I'm incredibly lost and very new to understanding all of this! Thanks in advance. 

Topic by SonyaS2    |  last reply

ReHab for Li-Ion Batteries??

Is it possible to get more life out of Lithium Ion batteries that no longer hold a charge? These things are great when new, but for the cost, they seem to crap out in a yr or 2. Specifically, 18v Ryobi cordless tool batts.

Topic by Toga_Dan    |  last reply

What makes a battery corrode?

 This device has been inside its whole life with occasional use. It consists of an LED, a resistor, three AA's in RatShack holders, and a push button. For the second time one of them has corroded and split open; IIRC it was in the same slot. Is the holder crappy? Am I buying punk batteries? Circuit issues (this was my first soldering project)? Basically, does my circuit need trouble-shooting or is it just dumb bad luck? Thanks!

Question by ToniRose    |  last reply

LM3914 Battery Level Monitor

I am trying to make a Battery Level Indicator using the LM3914 IC. The problem I am facing is... where you see those 3 LED's my voltage increases on the pot, where as when the LED's are all the way on it decrease across the pot. I am using a 9V Battery where I want the red led to show depletion  of battery life around 5 or so volts  how can I achieve this. Can someone please help me with this?

Topic by dominick.j.pezza    |  last reply

LM3914 battery level Indicator ?

Https://     I am trying to make a Battery Level Indicator using the LM3914 IC. The problem I am facing is... where you see those 3 LED's my voltage increases on the pot, where as when the LED's are all the way on it decrease across the pot. I am using a 9V Battery where I want the red led to show depletion  of battery life around 5 or so volts  how can I achieve this. Can someone please help me with this?      Which pin can I set to 5v and how?

Question by dominick.j.pezza    |  last reply

Need help on how to build a Remaining Battery Charge/Life LED Meter?

I've been searching for months now for an Instructable or step by step guide on how to make a remaining battery charge meter. If anyone can help i would greatly appreciate it : ) Ps: i have included a very poorly drawn diagram of what I'm seeing in my head. Gotta love paint.

Topic by ubberd    |  last reply

AC Power from a Battery

I've got a Garmin Forerunner 201 that is recharged by plugging a cord into the wall socket. It has a cradle type device that serves to connect the device to the cord. It does not have a USB connector.The battery life is 12 hours, but I'm going on a four-day bike ride (camping overnight), so I need a way to charge it since I won't have access to AC power.I've searched projects and gotten lots of hits on creating a USB charger from batteries, but I can't find anything on creating a power pack (with outlet) for charging my device.Does anyone have any suggestions on what I could do/use? I'd hate to not be able to track my route after I'm done.

Topic by samfelis    |  last reply

18650 battery pack question

Hello everybody, I need to install (build) a recharging battery pack for my plant shelf.  it will be running an arduino nano, just 3 leds (3mm 20ma each) 1xNTC and 1x water sensor probes (nails).--  no LDR no yellow LED. . I was thinking about getting a 2x 18650 battery holder - I need more battery hours, should we wire the batteries in parallel to get more mAh and boost them 3.7V to 5V. so basically this is what I am trying to custom build to get more hours; DIY Mobile Power Bank Case Kit . I would just buy the mentioned product BUT under specifications>battery it says the capacity range: 1000mAh and below. but the batteries I have are 3.7V @ 5000mAh. does this mean that the remaining 4000 will be lost because the system can't handle it?  . basically what I am asking for is how can I make a long lasting arduino nano powering 18650 battery pack BUT also with a recharging module. these are the items I found that may work together, please remember that I have no electrical experience from before. I have learned everything that I know from instructables, this is a too advanced build for me to figure out without asking a few questions. thank you for your patience, let me know if I have to clear anything out. batt holder:  recharger: boost: am I even in the right track with this thing? can these be connected together and a switch. again, the goal is max battery life.. maybe add 4x 18650 - 2in parallel + 2in series, 7.4V to arduino Vin, eliminate the booster, even more battery life ? . thank you in advance, love & peace akin,

Question by Akin Yildiz    |  last reply

How long will 2 aaa batteries last when connected to a 5mm 25ma 3.3v led?

The batteries are connected to a simple switch, then to the LED. Just wondering - hours? Days? Is there a better option for power supply? I need them to last around 150 hours.

Question by lentze    |  last reply

Is it possible to extend the life of my xbox 360 controller by replacing the 2 AA batteries with 1 9v battery?

I know i would need a regulator. Also, if this is possible please provide me with a list of other parts. THANKS!

Question by conrad2468    |  last reply

Why does my iPod Touch suddenly have terrible battery life? Answered

I have an iPod Touch 2G (8GB), which is running jailbroken 4.0 firmware.  The battery life was fine, but suddenly it started decreasing.  If i leave it in standby (locked) overnight, the battery will go from 100% to 35% without me even using it.  does anyone know why this is happening? is the battery just old?

Question by budabob07    |  last reply

old discharged electric wheelchair batteries

My paralyzed wife passed away in 5/2007 and her 2 electric wheelcairs that are no longer in use have thouroly dead batteries. I don't know what kind they are other then they are a sealed unit. I want to sell them but can't with dead batteries. Can they be brought back to life? The on board chargers don't seem to do anything.

Question by Jerry S    |  last reply

How can I make a solar charger for extended battery/capacitor life?

I want to build a solar charger that could keep a rechargeable, say, CR2032 battery always trickle charged without damaging anything. I want to make this circuit as simple as possible. I want to just hook up a solar panel, with an operating voltage of 3V that delivers 1mA, to a rechargeable CR2032 that was in-use. Assuming the solar cell was delivering power for 12 hours in the day, would what could go wrong? I'm sure there could be some danger, but I don't know enough. Do I need a charge regulator? Can I charge the cell and also consume power from it? If it's forgotten about for a year, will the battery explode? Can this be done with a capacitor? Can I keep trickle charging a capacitor that is attached to say a heat sensor which uses very little power?

Question by JamesS691    |  last reply

Increase battery of a portable usb charger?

I have a  portable usb charger that has these specs: Li-ion 3.6V    1200 mAh Input: DC 5V    400 mAh Output: DC 5V    450 mAh Can i add an old battery that has 3.7V and 1150mAh to the charger and increase the battery life of it? Would it be safe to just hook up the the negs to negs and pos to pos? Also what would be a better way to increase battery of the charger without buying a new unit?

Question by yitmat    |  last reply

Get battery charge level in Linux

I have a small all-in-one motherboard that runs Linux ( It only needs 18V to power up and the battery from my Black and Decker drill is 18V. I am able to get the board  to power on by holding some wires on the leads of the battery. My question is, can Linux detect how much charge is left through a DC jack? Or would that take some extra circuitry? My goal is for the user to see a percentage of battery life left (like on a laptop) and maybe to shut the board down if the charge gets too low. Any advice is appreciated.

Topic by bwallen    |  last reply

12V car battery indicator

Hi, I have been trying to design a circuit to monitor my 12V leisure car battery, I'm thinking this should be fairly simple, but its been years since I did any real electronics. So the basic idea: Use the circular bargraph to indicate the level of the battery when a momentary push button is pressed the circular LED bar graph: So the range of the battery would be something like 10.5V to 13.5V, there are 32 LEDs in pairs, so essentially 16. 1. So if we take the first LED pair, this should illuminate when less than 10.5V, so that should be easy, as long as there is some life in the battery it should illuminate 2. The next LED should only illuminate at the next step, 16 LEDs, 3V range 16/3= steps of 0.2V So at the following steps: 10.5, 10.7, 10.9, 11.1, 11.3, 11.5, 11.7, 11.9, 12.1, 12.3, 12.5, 12.7, 12.9, 13.1, 13.3, 13.5. So for 10.7V I guess I should use resistor before each LED. 3. The LEDs should light up after a momentary push switch is triggered, I would like this to be graceful, so the ring lights up smoothly one LED at a time as the voltage increases, I guess capacitors between the resistors and LEDs? This is the simplest way I can think of doing it, I have seen circuits which use a LM339 chip, but that can only monitor 4 voltages, perhaps 4 of these in series could do the job? I think this is the way to go rather than using inline resistor/ capacitor pairs? So I am a clear novice when it comes to electronics (but I'm enthusiastic), so if anyone can help me with this I would be more than happy to put together an instructables how to, something similar has been done before: In that example only one bar is lit, I want the other bars to stay lit. I can use Eagle to make the PCB diagram and get it printed, but I need to figure out what components I need and how to do it! Thanks for any help. Gary

Topic by garynobles    |  last reply

RPG-Style Stat Bar for Every Day Life?

If the title alone didn't cover it, does any one have any ideas on how it would be possible to make a Status bar like the ones in most video games as a real object? I'm thinking it needs to be able to change, be relatively useful, small, and battery powered. Any thoughts on the subject are appreciated! 

Question by Numbuh1Nerd    |  last reply

Four instructables with same titles!

I have notice that they are four instructables that has exactly same titles! Wow!This is the first one that came out...Increase battery life for electronicsAnd another one... (That one is mine)Increase battery life for electronicsAnd another one!Increase battery life for electronicsAnd the most recent one...Increase battery life for electronicsIt is quite amazing, also please vote the instructables if you like them...

Topic by Plasmana    |  last reply

would 4 speakers on two 2-channel amps require twice as much power as 2 speakers on one 2-channel amp?

Also how do i work out the recommended (capacity) volume of the enclosure for 2 or 4 speakers? would it being used outside require a larger enclosure than usual to adequately broadcast sound?

Topic by ambientvoid    |  last reply

Electrons flow from positive terminal to negative terminal inside a battery? Answered

If a bulb is connected to a battery, then in the bulb the direction of current is such that it flows from negative terminal of battery to its positive terminal. Whereas inside a battery electrons flows from positive terminal to negative terminal. How is that possible? If this is true wont it look like saying that a battery has infinite life time as battery discharges via bulb but charges inside by itself.

Question by deepakmurali    |  last reply

iMAX B6 Digital Battery Balance Charger

Hey i just found this cheap charger on eBay and i was wondering if it would be able to charge a pack of 18650(unprotected) 3P4S safely? i figure i could just run the charger to each 3P set and be confident it want gas/explode?

Topic by andrewlapham2010