Introduction: New Life to Dead Ni-Cad and Alkiline Batteries

Picture of New Life to Dead Ni-Cad and Alkiline Batteries

In this Instructable, I'm going to show you a secret battery company's DON'T want you to know!!! How to give new life to dead Ni-Cad batteries AND disposable batteries.

This was not 100% my idea. I got the idea from: Bring Dead Ni-Cad Batteries back to life

Disclaimer: This project is extremely dangerous. High voltage capacitors can hurt or even kill you. I am not responsible for your actions.


Step 1: You Will Need

Picture of You Will Need

You will need the following:

  • a oscillator circuit (I’m using a self oscillating relay parts, for old schematic, relay, 100uf cap, and clips)
  • A high voltage diode with at least a 200V rating (I had one lying around)
  • heavy duty alligator clips or wires
  • A high voltage capacitor or a photo flash cap. ( you can get it from a disposable camera with flash)
If you want, you can use the circuitry from a disposable camera Here’s the instructable.

Step 2: Why They Die and How It Works

Picture of Why They Die and How It Works
Well, They don't exactly 'die'; it's sulfur crystals that form inside the cell, this is caused by:
  • Overcharging
  • Leaving the cell in the discharge state for a while
  • high temperature
After the crystals have begin growing inside the cell, they will eventually touch both ends of the cell terminals. This shorts out the cell from the inside and prevent it to being recharged again...

luckily, sulfur crystals can be easily destroyed, by putting a hefty surge of current through the cell... This vaporizes those pesky crystals and the battery should be good as new again!

This should work most of the time, but if the battery has leaked, nothing can recover the batteries.

Step 3: Make the Zapper. Part I

Picture of Make the Zapper. Part I

To make the zapper, wire up the relay to the first or second schematic.
(make sure that the relay has two sets of contacts if you use the first schematic.)

* for the first schematic, Connect one end of The relay coil to ground.

* connect the other end of the coil to the "normally closed" terminal switch

* connect the arm switch part of the relay to +V.

* now connect the 100uf cap. (see the first picture. not schematic 1)

* Connect the low voltage terminal to the transformer to ground.

* On the other set of contacts, connect the other low voltage terminal of the
transformer to the two stationary contacts, and lastly the armature to +V end of your
power supply (see the second picture)

Step 4: All the Steps Part II

Picture of All the Steps Part II

Now, lets make work on the high voltage end of the transformer.

* connect the diode to the transformer

*test the output of the transformer. try to get the lamp as bright as you can. the brighter the lamp, the faster the capacitor will charge.
NOTE: (you may need reverse polarity on the diode [last picture] ).

* connect a high voltage capacitor to the free end the diode and the other end of the transformer. (make sure polarity is correct) this is the same for both old & new schematics. [pic 1]

* test the cap by turning on the circuit (in other words, charge the cap) and then
short the capacitor

* You should hear a loud “pop” and see a flash of bright blue light.

* Now charge the cap. then, connect the two output leads to the
dead battery’s + and - terminal.

*note; you only touch the output of the capacitor to the batteries, dont keep them on it the curcuit is designed just to apply a split-second long jolt to them.

Now just recharge your Ni-Cad batteries like normal!

Step 5: Troubleshooting & Photo Gallery

Picture of Troubleshooting & Photo Gallery

if your rechargeable battery's STILL don't work:

* check to see if the battery's leaked, if so, this method won't work go to step 2 if you
   want more info..

*make sure the battery shocker makes bright blue sparks when the terminals touch.
  if not, make sure you read all instructions correctly.
  (you may have to play with the diode AND capacitor polarity.)

            / || \
          /   ||   \
( photo gallery )

Step 6: Extra, Recharge Disposable(non-rechargeable) Batterys

Picture of Extra, Recharge Disposable(non-rechargeable) Batterys

(CAUTION: these batteries were not designed to recharge, read the warning on them. some of the better brands like durcell will explode or leak if not used properly, they tend to do so more often because those company's pack them full of the cr/\p. keep a close eye on them for any signs of explosions. if they explode not only will they make a mess, fire hazard, and worst of all, they wont hold a charge because the exploded, their gone!

this is actually VERY simple!!!

1) gather a few things

+ a 4.5 volt regulated power source
+ dead disposable battery(s) { first image }
+ a 3 volt battery holder { like second image }

2) next, connect the positive (+) from the battery holder to the positive (+) on the 4.5V regulated power source

3) after that, connect the negative (-) from the battery holder to the negative (-) on the 4.5V regulator

4) (optional) recharge the dead batteries from that "EASY" butten you got from staples and then insert them back in

5) (optional) now your DONE!!! now just press that EASY butten from staples!!! *.*
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . U


holymoses (author)2015-07-14

I doubt this procedure!

-max- (author)holymoses2015-07-20

You are probably right. This procedure does work in some cases, but most cases of dead drill batteries I have found, the batteries have leaked a LOT, and they are permanently physically damaged from that point on. I found it is more economical and reliable to simply replace the cells with ones bought online.

holymoses (author)-max-2015-07-20

Actually you don´t need high voltage, just some higher current and something like a bistable multivibrator, so just a NE555 Flip-Flop.

This way you can easily refresh lead-acid batteries, but I still doubt this way for Ni-Cells and Alkalines, especially primary cells.

For Ni- (Mh)-Secondaries you just have to pass some cycles discharging and recharging for refreshing them.

apillai5 (author)2014-03-30

What Kind Of Relay Is It ?? Can U Send Me A Link To Buy This Online Because I Live In India And I am Just 15

-max- (author)apillai52014-03-30

I don't know off the top of my head, I just bought the first one I came across at radio shack. Some sort of 12V 10A DTDP relay that looked big and powerful. Due to all the sparking, the relay gets VERY hot and in fact the one I show in this 'ible had a complete meltdown! (the contacts are no longer lined up properly) I used to use a smaller relay, but after awhile it stopped working due to corrosion on the terminals. this is a very common failure mode, but it is very easy to fix If you can open up the relay and clean off the contacts with a very fine grit sandpaper. Just try to get one that looks east to pull apart.

apillai5 (author)-max-2014-04-02

I Want A Charger For My Capacitor Bank And i M Charging It With a Transformer . I Have To Switch It On And Off Rapidly My Hands Pain Due To This :P . My Question Is That How Can I Charge It Without Switching It On And Off
. Yes I Can Charge It Using A Disposable Camera Flash Circuit But The Transistor Dies Really Fast So I Got An Idea Of This and Went Through U r Post And came To Know That A Relay Or a 555 Timer Can Be Used
Can U Plzzz Send Me A Simple Schematic For This Project .
(I Am 14 Yrs Old So I Dont Know Tooo Much About This . Srry For My Errors )

Electrospark (author)apillai52014-09-11

maybe you could try to build a one transistor joule thief type inverter...

-max- (author)Electrospark2014-09-12

You can definitely use a single transistor circuit, although it would have to be more powerful than the joule thief. Another commenter has stated a while back the camera flash circuits would fail after some time and same with the bug zapper one's.

Electrospark (author)-max-2014-09-12

yeah, that's the main problem with them.

i made a one transistor flyback transformer driver that was operated by a 1.5 volts battery at an amp draw of around 20-140mA and the output was around 350 volts, made my CFL to run quite well. :)

that would probably be a nice electrolytic capacitor charger!

ill do an instructables about it one of these days...

apillai5 (author)Electrospark2014-09-12

Please do make one

Electrospark (author)apillai52014-09-13

I will, but, it will be my first instructables so it might be a bit messed up. XD

-max- (author)apillai52014-04-03

Didn't you say in your last comment you are 15? Anyway, to charge HV capacitors, you need to either build a inverter, or build one. They are kits online to build small high voltage DC sources that should work. I presume you are trying to charge photoflash capacitors for use in something like a rail gun. Honestly, it is not a good elidea for a beginner to mess around with such deadly things, you could easily get vascular defribulation and die from HV caps. But if you feel you know electrical safety well enough, then you can use the relay-based driver to drive a mains transformer in reverse, and rectify the output with a few 1N4001 diodes. I go into detail about this in my 'ible on reviving NiCad batteries.

I personally have not had any luck with the 555 cuicut either since the voltage transients kill even high power transistors easily. Good lock and be safe.

apillai5 (author)-max-2014-04-04

Yes I Got Shock About 20 or 25 Times But I Am Still Alive And i Use A Saftey Glove Made From Rubber While I am Playing with The Caps I Have About 13 Caps Of 130 μF 330V

There A Guy Named Jelte1234 He Told Me To Use A Diode
How Can I Use A Diode The Transformer Has 4 Pins 2 Pins Of Primary And 2
Of Secondary . This Transformer Actually Converts 240 V Ac To 12 V Dc
So I reversed It And Now It Give About 220 V Ac As I Switch It On And
Off . I M Using It As A Step Up Transformer . I Use It To Charge My
Capacitor Bank . Also I Have Have Tried A Bug Zapper Circuit But My
Transistor Died Very Fast ( Disposable Cam Same Issue ) . So I Use This
Transformer Also I wanted To Make A Inverter I Tried To Light a CFl Yes
It Lights Up But It Is Difficult To Find Out That Is It Burning Or Not

-max- (author)apillai52014-04-04

I believe the reason your transistor circuits are failing is because the initial impedance of the capacitors is very low. You need to limit the current to whatever the maximum current the HV inverters can handle. Also, you can probably replace the transistor with a higher quality PN2222, or high power transistor. that is a low of capacitors, and I am assuming they are wired in parallel, so the capacitance is around 1700µF (Ctotal=Ca +Cb +Cc...), and at 200V, this is 34 joules of energy (1/2C*V^2). That is quite a lot of joules!

A small inverter made with a single PN2222 might only deliver 0.6 joules/second, or watts. I just made this assumption on the fact that you might be running this off of 3V, and assuming the average current through the transistor is 200mA and into the transformer I did not measure this, so it is just a guess. I did not consider losses so the output is probably less.

Anyway, while the capacitors hold no charge, I will assume the impedance is 0 (short circuit) and we need to add resistance to the circuit to prevent the capacitors from acting like a short. first, we need to know the output current, which, again, I am going to assume is in the order of 1-3mA (W=A*V, 0.6=200*A; A = 0.003) This is assuming a load that draws less than or equal to this, means the output will be exactly 200V. Next, ohm's law tells us that V=IR, we plug in the numbers, 200V=0.003A*Ω, solving for R we get approximately 66.6KΩ. Using the RC time constant formula, I have figured out the time it will take to charge the capacitor is approximately 80% charged (% is the relation between charge reached in 3 minutes vs. the maximum charge possible w/ 1700uF@200V). Another method is to use a constant current load in series with the inverter and capacitors to limit the current flow, but the current load would have to be able to handle the high voltages.

Up on step 4, I show how the secondary is wired. The diode and capacitor are in series if you still plan on using the relay circuit. Also, some of the schematics are wrong in terms of the wiring used, so you may need to reverse the connections from, say, the normally open contacts to the normally closed contacts. My ignition coil driver using the relay will drive mains transformers very well too. You can use that scematic.

apillai5 (author)-max-2014-04-04

Sorry max i dont understand anything . I am Having a Transformer with 4 pins i searched the whole internet for inverters . but every transformer has 3 pins . so my question is what should i do . I should rather pulse the dc current right and send it to the transformer right ? :D

-max- (author)apillai52014-04-05

Do you mean four pins on the original secondary?

apillai5 (author)-max-2014-04-05

No Its Has 2 on The Primary And 2 On Secondary Total 4 . I m Srry But I Cant Find u r ignition Coil Plzz Send Me A Link

-max- (author)apillai52014-04-06

Here are the 2 images I wanted you to see. The second one is the one here, and it works fine, but adding a ~1uF film capacitor across the normally open contacts (the two that are not touching) will improve performance as it creates an LC tank circuit which oscillates at the resonate frequency of the transformer, boosting the voltage. the ignition coil driver (first pic) shows that capacitor in place, but you see how it is only a 3 pin device, the two coils are connected together at the bottom internally. just connect the primary where the old primary used to go. The output os of course connected to a diode and capacitor in series to discharge into batteries.

Also, why do you need a 1700uF HV capacitor for? that is unnecessary for this application, and you better have at least some hearing protection, just one of these caps are loud enough to make your ears ring!

-max- (author)apillai52014-04-06

That is exactly how my transformer above is made. The ignition coils, however have only 3 contacts, 2 are connected to the primary, and the 2 are part of the secondary, the neutral of the output is connected the the negative input internally. There are dldiagrams online for how these are wired internally use can use. However, you do not need to concern yourself with it's pinout. Just use that driver on the mains transformer.

-max- (author)apillai52014-04-03

Actually I just realized I was thinking you were asking about this in my ignition coil's 'ible. I have a more powerful design there if you want to check it out.

apillai5 (author)-max-2014-04-02

I Want A Charger For My Capacitor Bank And i M Charging It With a Transformer . I Have To Switch It On And Off Rapidly My Hands Pain Due To This :P . My Question Is That How Can I Charge It Without Switching It On And Off
. Yes I Can Charge It Using A Disposable Camera Flash Circuit But The Transistor Dies Really Fast So I Got An Idea Of This and Went Through U r Post And came To Know That A Relay Or a 555 Timer Can Be Used
Can U Plzzz Send Me A Simple Schematic For This Project .
(I Am 14 Yrs Old So I Dont Know Tooo Much About This . Srry For My Errors )

dillonxti (author)apillai52014-04-24

any relay will work just hook it right

mykiscool (author)2014-09-07

will this work with nimh batteries?

-max- (author)mykiscool2014-09-07

I've barely had success with Nicads, I don't think so. You can try, It is an easy enough thing to do.

iceng (author)2013-07-06

So your putting new life into dead Ni-Cad and alkiline batteries
by momentarily hand zapping them with high DC voltage.

Have you tried battery recovery as a business service for people like me ?
I have jars of dead batteries and would enjoy revitalizing them.
What is your % success rate ?


jbaker22 (author)2012-02-15

Hey Max, I was wondering if you could tell me the voltage amperage, and frequency that it puts to the battery? I also want to know if I should fix one cell at a time? I tried making a nicad battery fixer with these ratings and it hissed like it was about to explode, I put 15 volt at 1 amp 60 Hz to a 7.2 volt nicad. Thanks for publishing the instructible.

-max- (author)jbaker222012-02-15

any source of high voltage DC should work. (a camera flash circuit, maybe)

do you mean you powered the circuit off the 15V 1A power supply? if so,
did the relay buzz, charge the capacitor, and shorting the cap made make loud blue sparks? (step 5) 

the freq. in not important, im just running a mains transformer from the pulsed DC, (so it will make the high voltage,) im not sure, maybe about 50-80Hz-ish im guessing by my ears from memory since this wasnt a final project

that charges a large capacitor with DC and jolts the battery with it.

do one cell at a time and don't hold the terminals on, why your batterys went POOF, they were probably bad beyond recovery.

jbaker22 (author)-max-2012-02-16

I hooked15volts ac to separate diodes and then a capacitor. This was connected to the 7.2 volt I tried to fix and threw away. My curcuit was fine no short curcuitsand no sparks or smoke. It seems like you build a device similar to a battery desulfater low amperage and high current.

-max- (author)jbaker222012-02-16

so you went directly from 15Vac to diode/capacitors and to the battery. well the key to this is high voltage. 15V at 1A is too much amps and too little voltage.

my guess is too much power was absorbed by the batteries and not instantaneously destroying crystals. and the low current, high voltage charges the capacitor to about 200-600V and [when you touch the terminals to the battery it] zaps the battery instantly. smoke should only come out if you hold the electrodes on for more than a few seconds, with high current.

i have been doing this to drill batteries (took apart to get to individual cells) and the 4 i had, i only got 2 of them to work. (the other ones had bad cells in them)

i have the impression that you are holding the terminals on and leaving it that way. this isnt like a charger, i think i forgot to mention tn the instructable. sorry about that...

jbaker22 (author)-max-2012-02-22

I was wrong I just gave it 15v dc from a supply @ O hz

-max- (author)jbaker222012-02-23

i re-read your last post a bit more carefully, and it looks as if you just 15Vdc power supply. was this connected to a dc to HV dc converter? (in this case, a relay circuit?)

if you already have a AC supply, then just connect that to the transformer directly. (not turning AC to DC just to turn it back in a AC-ish current)

just connect the ac power supply to the (what used to be) the secondary of the transformer. the (what used to be) the primary to a rectifier and capacitor in series with the what used to be the primary, now the secondary.

let the capacitor charge, and and short the cap out to test. turn it off, discharge the cap, and connect two wires to that. those are the wires to touch to the battery after the cap is done charging. there should be a diminished spark. at one or both terminals.

mangelox (author)2011-11-02

This was really interesting and informative. I especially like your schematics...makes your instructions much clearer.

-max- (author)mangelox2011-11-02

thanks, i draw them schematics in paint. but the ones on this page or for other circuits. they just happened to work!

ZxxxY (author)2010-05-29

Havent your disposabe batterys explod? Recharging dispsables spounds very scary to me!please someone insire me that it is safe.

-max- (author)ZxxxY2010-07-09

i now got some news that it will work for a while, but since the battery's AREN'T designed to recharge. "after a while of charges, they will catastrophically fail (BOOM)" one tells me.

-max- (author)2010-06-02

at wost case scenario, they will leak.  usually they just get VERY warm. i only tried with alkaline battery's