Low Battery Indicator for 2x AA Batteries

How would I create a circuit which turns on an LED when the voltage goes below 2.5V? I am using 2x AA batteries

Asked by john8369 5 years ago


How to solder ni-cad batteries together for battery pack.

I want to replace a bad battery in an eighteen volt pack, but can't seem to get the solder to adhere to ends of battery. I thought about welding, but don't want to damage batteries. Any suggestions.?

Asked by mangelox 6 years ago



is there an advantage to having a battery with a higher mAh?

I have a Pentax digital camera that came with a D-LI88 rechargeable Lithium-ion battery with a 3.7V, typ.740mAh (2.8Wh), and min.700mAh. I want to buy an extra battery for it. I can find batteries with the same 3.7V, but the mAh are different.

Asked by joypain 7 years ago



Battery Charging?

Hello, So I have a 9.6 volt  NI-CD 4 hour quick charger and the battery(600mah) that goes with it, but I was wondering if I could charge a 7.2 volt 2000mah, Ni-Mh battery with it. If i can for how long?

Posted by ben2000 2 years ago


How to re-charge Duracell 21/23 Batteries?

Can a dead(drained) Duracell 21/23 battery be re-charged with-out it exploding in your face?

Asked by Tonester 7 years ago


Electric Motorcycle batteries

Hi, I have an electric e-motorcycle (Road Runner -several years old) and I need to get new batteries ASAP. Inside it has 2 rechargeable batteries. Does that mean I need to get 2 - 12V batteries, whatever Watts I like, based on however much horsepower I need.

Posted by MielV 7 months ago


How do I solder wire leads to a 12v 2amp battery?

I am trying to repair my son's electric quad.  I thought it might be the batteries but the batteries are both reading 12v.  I had to cut wire leads that were soldered to the battery so that I can test the batteries.  Now, that I know it is not the batteries, I have to solder back the wire leads to the batteries.  I was soldering the wire to the negative post and I was doing fine, however, I must have touched the positive post and I got a small explosion.  It scared me so I stopped. The quad uses two 12v 2amp batteries that are wired together.  The wires then have a lead that plugs into the quad.  I need to wire the batteries back together.

Asked by Jafsga 5 years ago


How to use batteries in a Series-Parallel Combination?

   Is it possible to use 4 AAA Duracell batteries instead of 2 AA batteries if I were to put it in some form of Series/Parallel combination? Would it keep the same voltage and stuff to not interfere with the electronics of something but just increase the time between changing batteries? What would the layout look like for this? Thanks Instructablers!

Asked by ranaakamarth 7 years ago


How do I dispose of batteries the green way???

I've always heard that batteries are really bad to put in a landfill... But I was wondering how/where to throw them away or recycle them.

Asked by mac100 9 years ago


Batteries and charger? Answered

So I got one of those one cell battery bank that come also with a little crank generator. So far I took both of these apart to make one into a 2cell. So now these batteries are a parallel, my ? is if the voltage stays the same with the charging board and the mah is double this should not effect the board correct? and or the batteries. So far its been working both batteries reads the same voltage so the charging board must work. Now hear is the thing that I am concerned with, if I was to add 6 more into a parallel then all batteries would be the same MAH right. This should not damaged the board?

Asked by dominick.j.pezza 3 years ago



What is the optimum charging voltage for 1.2 volt ni-cad rechargeable AA batteries? Answered

I am going to build a solar panel that charges these batteries so i I need to know the best voltage to charge them.

Asked by airsofter1 8 years ago



Arrrrr help me please... I want to convert AV (240v) powered fairy lighst to battery power?

Hi all I am trying to convert some fairy lights to run on batteries.  the string of lights after the adaptor run on 24VAC 250mA 6VA...  as I expected when I combined 9V batteries to produce 27V/ the batteries ran the light well (brighter that off the mains) and also as expected after about 1.5 hours went out. Now I was wondering if there is some way to wire batteries to run these lights? size needs to be kept to a minium as does cost.. Now I know that If I was to use LED lights this would be simple. but that is not possibe as I have already got the 50 strings of fairy lights :(   any help would be great... Cheers.. Ben 

Asked by ben.s 8 years ago


Voltage-capacity relation discharging an alkaline AAA battery?

Let's say I have a fresh alkaline AAA battery, 1.5V, 1200mAh. Also, let's say it discharges itself with 3% per year, just lying in the shelf. After one year, has both voltage and capacity been reduced 3%, or just the voltage? If not, how much has the capacity dropped then? I also wonder if the battery is being discharged the same  way, when in use? E.e. is the proportion between voltage drop and capacity drop the same on the shelf while in use?

Asked by karolina81 1 year ago


Camera/Battery Mystery

I'm trying to solve a mystery with an old camera of mine(a kidak cx 7330). It showed a low battery indicator with a fresh set of batteries, as well as some older ones-so i assumed it was broken. Once i had it replaced (which was overdue anyway, its like, 5 years old), i popped in a set of rechargables which i got with the new camera, and it worked. i tried with another, not so fresh pair of energizers ... and it worked too.  (all batteries are AA- i prefer cameras that use em, since they arn't toyishly small) Having gotten myself confused, i checked the voltages on all 3 sets of batteries. The fresh set was manganese, and 1.7v. The rechargables (nimh) were 1.4V and the not so fresh pair of energizers(alkaline) was 1.6 v and both worked. I'm wondering (other than what the hell is going on), if electronics have some kinda overvoltage protection, and if that was what was triggering off the issues, and if i ran down the manganese batteries to 1.6v or below, i could use them - that way i'd just use em for something high drain, and switch to them once its done.

Posted by faileas 8 years ago



How do I make an alkaline button cell "flatpack"? Answered

For my application I need an 12V A23 battery, but to optimize space I would like to rearrange the tiny little 8xLR932 alkaline cells as shown on the picture. I want to connect them i series, just like an A23.  The final product is disposable, so I'm thinking of using shrink plastic around the whole thing, but I have no idea which is the fastest and easiest way to connect them. Solder tabs? Wire+glue? Wire+tape? Anything else? I am also a little worried that all the connections will steal voltage from my battery pack. Will this be a great issue? Thanks!

Asked by karolina81 1 year ago


Can you recharge rechargeable batteries with a normal battery clip?? Answered

Can you recharge rechargeable batteries with a normal battery clip like you buy at radio shack? (batteries will be charged via solar charging circuit)

Asked by monkhm 7 years ago


Fixing NIMH Batteries Answered

I am curious if there is any way to possibly fix NIMH batteries. I saw at http://www.youtube.com/watch?v=L1RxhgFEPSM how a freezer fixes them, but it did not work. It would be great if somebody with dry ice and dead NIMH batteries would try freezing these batteries (safely).

Asked by jbaker22 6 years ago


Polyacene Batteries

Here's some wierd batteries that seem like really dense capacitors. Does anyone know how to cahrge them? Do you just touch both ends to a battery?http://www.goldmine-elec-products.com/products.asp?dept=1235

Posted by guyfrom7up 10 years ago


Replacing three 12 v batteries in an electric scooter?

I have an x-treme scooter 360 and the batteries are dead. i have 3 12v replacement batteries, but i do not know how to replace them? does anyone know...

Posted by denniswilliams 10 years ago


extracting batteries from recycler

Has anybody tried to remove batteries from this?there are a bunch of dead 9V's in there and i want to get them to make battery clips from them.but the lid is small and it is spring loaded.I was thinking a speaker magnet on the end of a string and just drop it in and you get whatever you get.are batteries magnetic...

Posted by ledzep567 10 years ago


Quick Question about Batteries

I'm sure this is a really simple question, but I'm still new to all this electricity stuff. If I had two D batteries in a battery pack formation, so I'm drawing current from both of them, if the wire coming off the positive doesn't connect to anything else, and neither does the negative, will the batteries drain faster than they would if they were just sitting there? Here's a (cruddy) diagram.

Posted by Bran 10 years ago


External batteries for hotglue gun

I was wondering if I could mount batteries on top of a glue gun. I cut the wire of the cord and i had two minicords and i ran those out of a hole i made in the top of the gluegun. any ideas on what batteries, a switch on/off method? and also how to connect the wires to the batteries would be extremely appreciated.

Posted by ledzep567 10 years ago



Let's just say i want to recharge a rechargeable battery with another AA battery... Answered

(I know it wouldn't work very well but lets just say that it does) does the positive part of the regular battery go to the positive part of the rechargeable battery? I am trying to recharge a battery and i don't want to ruin the rechargeable battery so i just wanted to make sure that i was going in the right direction...

Asked by ML159 9 years ago


Would setting batteries in series combine their mAh? Answered

So say I have four 2,000 mAh batteries, and I set them in series. Would that give me 8,000 mAh?

Asked by Sargebubbles26 5 years ago


What small replacements (preferably cell battteries) are there for two AA batteries?

I would like to replace two AA batteries with a cell battery or something smaller -  I have tried with a small 3v cell battery but it doesn't seem to work.  Is this because of the current?  Any tips on alternative power supplies?

Asked by shmelfhelp 8 years ago


batteries in my down tube

I'm thinking I would like to fill my down tube with a battery so that I could run lights and satnav and maybe even a heated saddle for cycling in the lovely Scottish winters.  Does anybody know where I could source suitable batteries?  Thanks

Posted by daisyboi 6 years ago


Why Sub c batteries used in battery packs for drills?

Is this somehow related to discharge rate? I'm trying to replace existing sub c batteries, but their price is put me off. Can anyone provide some info? If use equal capacity aa, what the difference gonna be (once again discharge rate)? I would  really appreciate any info about this.

Posted by Extasy 6 years ago


Best type of batteries for solar panel use? Answered

I'm looking for something with a long lifetime that needs little maintenance, and is recyclable. Currently leaning towards "Absorbed Glass Mat" batteries. Has anyone had any issues using those, is there something better out there?

Asked by action_owl 6 years ago


Any fun, weird or quirky uses for old, rechargeable, dead batteries.?

Any fun, weird or quirky uses for old, rechargeable, dead batteries.?

Asked by ostrich160 7 years ago


What can I do with my dead AA batteries?

Besides throw them away.Edit: Or make them into art. You can make anything into art, so that's a given.I have both rechargables and non-rechargables. And I can't be the only one with a buttload of dead batteries idly lying around the home left over from the 90s.

Posted by bodybreak 10 years ago


Replace r/c batteries

Hi, does anyone know how to replace r/c car batteries with normal AA cells (or pp3 or whatever)? This is really annoying me coz I have an old r/c car (pretty good one actually) but the battery has died and I was wondering how to replace it (or 'refresh' it if this is possible, which I don't think it is...). It would also be helpful to know a technique for finding out the voltage/amperage of the old batteries so I can fix it without blowing the electronics. Pictures would be attached but the uploader isn't working right now; I'll get them up as soon as possible. Thanks guys,

Posted by TurboSnail 6 years ago


how to bypass the safety on a battery charger?

Ive been working on a cd welder for battery tab.. very simple car audio capacitor with a battery charger. today i rebuilt the whole thing with new leads wiring and new battery charger that will shut off when it hits a full charge. now it wont charge at all because it apparently wont charge anything thats not a car battery with proper voltage already existing. since the capacitor dumps the charge and leaves nothing, the charger just thinks there is nothing there. can anyone give me a crash course in float chargers and how they work so i can single out what i need and bypass everything else

Asked by snowfox222 3 years ago


Can a "dead" rechargeable battery be resucitated?

I have a Filter Stream Ultra Dust Tamer 4500 that doesn't recharge.  Is there a solution; a replacement part; any help at all?  I really don't understand rechargeable batteries.  I think they may get fried if the transformer is left plugged in too long??  How long is too long?  I know this question applies to all rechargeable batteries with transformers, e.g., cell phones, portable vacuum cleaners, cameras and on and on.  Thank you.

Asked by randithedog 7 years ago


Uses for old, but good cell phone batteries?

I have recently come into possession of several 3.7v cell phone batteries. I have toyed with the idea of using them to power a mag light type (D cell) flash light. Any ideas as to carry this out? Or just any ideas for re-purposing them?

Asked by macruadhi 9 years ago


Motorola Bluetooth charger to charge 3.7v li-ion batteries Answered

I have a little bluetooth charger that outputs 5.0V and 550mA, am I able to charge 3.7v li-ion batteries with this?

Asked by vallka 5 years ago


Wall charger for rechargeable batteries HELP!

Hi, I'm trying to figure out how to recharge these BATTERIES without having them blow up in my face. I'm very new to making my own electronics and a little timid when it comes to messing with batteries. I believe i need to use this DC jack connector? With this CHARGER? I'm using the battery to power 21 LEDS wired in parallel with resistors (3.4v 20mA) if relevant. I think i need to wire it up like in the picture. I guess my question is if i wire all these things together and try to charge the battery will it destroy something? Also if i wired two of these batteries in parallel can I still charge it the same way? How do i know i'm using the right DC jack connector and charger? Is there a specific switch i need to use? Any help would be greatly appreciated!!! Thanks!

Posted by kasmir 4 years ago


What can i do with 7.4V Lipo batteries?

I have 4 2000mah 7.4V lipo batteries just laying around from my cheapo drone. So i decided to do something with them, maybe make a flashlight or something, but i cant find any electronics to use with them besides RC motors.

Asked by RolandsB1 1 year ago


Looking for suggestions for making a very slim battery holder

I use a PDA that, through some questionable wisdom, is powered by two standard AAA NiMH batteries, but are not easily replaceable. They are plastic-wrapped with a heat sensor and two soldered connections which then connects to a circuit board. . These can be replaced by replicating the set up with tape and soldering in the  new batteries, which works fine, but is a lot of hassle. What I would like to do is design and make a battery holder that will cut out at least some of the more tedious parts. Preferably I would like to find a way to just unhook the connector from the circuit board, and then easily extract the two batteries and replace them with no soldering required. The problems are that the space is quite tight, so any method I try will have to be barely bigger than the batteries themselves.

Asked by wispr 8 years ago


Any fun, weird or quirky uses for old, rechargeable, dead batteries.?

Any fun, weird or quirky uses for old, rechargeable, dead batteries.? Not recycle as its not fun, weird and/or quirky. And please do not answer saying how it is. Thanks.

Asked by ostrich160 7 years ago



How to recharge these batteries?

I took apart 2 cordless drill batteries and there were 13 cells in each one, which were Ni-Cd 1.2 volts each. Also there were the numbers C DE35ND on them if that helps at all. I cut 3 off in order to form a 12v battery (it was originally 15.6v) but I dont know how I can safely charge it. I no longer have the charger that went with the drill, but I was wondering if I can just use a wall adaptor to charge them or do I need a better charger? All comments and answers are greatly appreciated!!!

Asked by Electronics Man 6 years ago


Is this lion battery bank expensive? 150AH @12-14v

I was thinking about how much would cost making a lion battery bank with enough amps/hours to feed a car audio system (stereo + sub amp). Since this setup would drain around 25-30AH I definitely want a battery bank with around 150 AH capacity to get at least around 4 hours of music at max potency. Woulds this be so expensive? I know that lion batteries are getting cheaper and cheaper, but any idea about how much would this cost? I have made a research on ebay and amazon, I could not get an average idea, and considering many brands lie about the specs, I better first ask here to hopefully get some references. Thanks.

Posted by johanx4 12 months ago


What is the best way to power a usb device with 2 batteries?

My project is to make a walking stick with a tesla ball at the top.  I wish to power a plasma ball ( like this one http://www.amazon.com/USB-Plasma-Ball/dp/B0052GSQ8A ) with just two batteries. The whole minty usb charger seems like overkill and meant for smartphones. This is a simple device that runs on 5v and 350ma. But I could not find any instructables anywhere for this.  I do not mind using 3 or 4 batteries if need be. Any link or suggestion would be greatly appreciated.  Thank you in advanced. 

Asked by d3icidal 6 years ago


Strange Electromagnet Observation

Hey everyone. I'm fairly new to the hobby electronics world, and today I decided I'd build an electromagnet. I wound my coil around a steel bolt, and I used 3 Duracell AA (1.5V) batteries for a power supply. When I turned on the switch, I found that my beautifully wound coil took a little bit of prying to get it off of the metal base I was working on. I thought "Let's try 9 volts!" So I grabbed a Rayovac 9V battery that I had around and hooked that up in place of the 4.4V (measured) bank. The Rayovac measured to be ~9V. The electromagnet was noticeably weaker. When I tested my magnet with just one of my 1.5V batteries, it felt like it had similar strength to the 9V battery.  Can anyone explain what might be going on? Short of that, could someone tell me how to measure the current coming off of each power source?

Posted by TheMike25 5 years ago