A Simple Step to Revive a Dead Ni-MH Battery

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Intro: A Simple Step to Revive a Dead Ni-MH Battery

Hello,

This is my first instructable. In this instructable i will show to all how to revive a dead battery( means the battery wont charge and will show 0V reading).

A few deays back i bought a pack of Ni-MH battery of 2400mAh. But some in them was not charging. So i had to search a lot to find a proper solution to revive the battery. So let me tell you the steps through which i got them working again.

Step 1: Cheking the Battery

First let us check weather the battery has any juice left in them after charging them for a while so that we can confirm that the battery is dead.

Here in the image you can see a dead Ni-MH battery.

Step 2: Reviving the Battery

Next we must take a similar battery of the same mAh which is fully charged.Then we have to connect the positive terminal of the fully charged battery to the positive of the dead battery and similarly connect the negative terminals.

Let the batteries be connected for a few seconds almost 20-30 sec. Then immediately check the battery voltage of the dead battery, if u see a reading above the 0 value then you can be sure that the battery is revived.

If the battery is still dead try the step again, i had a problem with 1 battery which did not work for this step the first time, later after some 3 tries it worked and is good as new. If you are still having problem check weather you are using a full charge battery for reviving the dead one.

Ones the battery is revived charge it until it is full.

That's all for this instructable.

Step 3: Explanation

"Some batteries die when a short developes between the positive and negative terminals of the battery This happens a lot with NiCd batteries and can happen with other chemistries. The short is caused by a metalic dendrite crystal. The electric charge between the two terminals of the battery encurages dendrite formation.

by connecting a fully charged battery to the dead shorted battery you willl get very high current flow through the dendrite. That will casue it to get hot and melt. Hopfully that breaks the short. Modern lithium ion batteries rarely short out in this way. Also lithium ion batteries are very sensitive to overcharging. If they overcharge they can catch fire . So I would not recommend this with lithium ion batteies." Thank you steven4872 for the explanation.

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    28 Discussions

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    JoeH242

    6 months ago

    Thanks for this insight. I had two AA Nimh in my Wii Remote, one had a NEGATIVE charge of -.71 volts. I thought I'd have to throw out the battery because my charger wouldn't charge it. I connected it like you said and left on for about 20 seconds. It was still negative, I did it again for another 30 seconds and voila! It was at .72 v positive. Then the charger would take over. Weird, but it worked - thanks again.

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    MaciejP12

    10 months ago

    It worked for a dead 5000mAh pack - I revived it with a 2200mAh fully charged one. It took a mere 20 seconds. Thanks a lot!

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    mr.peter.donoghue

    1 year ago

    This worked with Midland BATT5R .. A battery pack with 3 unknown Ni-MH inside !

    I simply connected the output terminals to a similar 6V source and then the pack would recharge - Interesting - there are 2 sets of pickups / contact on the pack - 2 are used for charging within the radio and 2 are used for output - Checking with a volt meter I was getting a reading from the output terminals 6.3 Volts BUT there was no reading across the charging terminals 0.0 V !! .
    I thinks Stephen4872 explanation about metalic dendrite crystal might explain a lott- I thought these batteries were complete gone ! -and was actually look on Ebay & Amazon for replacements when I happened across this site -

    Thank you Paul1212 - you saved the day ..

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    DavidC461

    1 year ago

    Thank you so much for this Instructable! I easily revived 3 dead AA Ni-MH batteries. 2 worked after one 25-second cycle and 1 took two 25-second cycles. This is great considering I have a "green thumb" and didn't want to throw these away!

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    Saiyam

    3 years ago

    Is this really possible? If yes then only with ni-mh? I think you should post a video to clearly show that.

    2 replies
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    CliffL12Saiyam

    Reply 2 years ago

    I just fixed my 18V NiCad lawn trimmer battery using Paul's method. Easy way to think of this is that there is a fine wire jumper connected across the positive and negative terminals of your bad battery. The charger current tries to push electrons onto the negative terminal of your battery to charge it but the electrons just take the easiest path through the jumper and nothing takes place in the battery. When you "boost" the shorted battery (exactly as you boost a dead car battery) you cause lots of current to travel through the little jumper and it heats up and melts. Now when you hook up the charger the electrons have to enter the battery and cause the chemical reaction that stores them there.

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    paul1212Saiyam

    Reply 3 years ago

    I dont know about other batteries.. But Ni-Mh can be easily revived this. Sorry i dont have a video of it.. All my batteries got revived and is being used in my robot. So i dont have a dead battery to take a video..
    The photo shows a dead battery being revived and we get an almost .8V output.

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    ionutzb

    2 years ago

    Hi, I bought a charger plus 4 rechargeable NI-MH Philips 2450 mAh seal, I had bad luck that one is defective, the value was 0 when I measured, I tried version of this article and it worked! Thanks for the nice tutorial, I saved the battery;)

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    fizassist

    2 years ago

    This worked great for me with 2 cordless phone batteries and a couple of jumper wires. I had to fast-charge the bad one several times to get it up to a voltage where the regular charger would take over, but now it works fine. Thanks!

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    gravityisweak

    3 years ago

    Whats the logic behind this? It makes no sense to me. You connected two batteries in parallel....to nothing. What am I missing here?

    8 replies
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    paul1212gravityisweak

    Reply 3 years ago

    Yes. This really works..
    I have tried it myself.. I tought the photos proved am right..

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    steven4872paul1212

    Reply 3 years ago on Introduction

    Some batteries die when a short developes between the positive and negative terminals of the battery This happens a lot with NiCd batteries and can happen with other chemistries. The short is caused by a metalic dendrite crystal. The electric charge between the two terminals of the battery encurages dendrite formation.

    by connecting a fully charged battery to the dead shorted battery you willl get very high current flow through the dendrite. That will casue it to get hot and melt. Hopfully that breaks the short.

    Modern lithium ion batteries rarely short out in this way. Also lithium ion batteries are very sensitive to overcharging. If they overcharge they can catch fire . So I would not recommend this with lithium ion batteies.

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    Yonatan24steven4872

    Reply 2 years ago

    Thank you for explaining it (I didn't how this was supposed to work), I think this should be mentioned in the instructable

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    gravityisweakpaul1212

    Reply 3 years ago on Introduction

    I understand now, thanks to some of the other comments. This technique will only save batteries that have discharged from sitting due to being in the store for a long time.

    The charger won't sense the cell if it has zero charge. When you connect the full cell to the empty one the full cell charges the empty one (a bit, enough).

    Once it's partially charged the charger can charge it back up fully. It will work provided the 0v cell isn't damaged, provided it only self discharged because it's been standing on the shelf too long.

    Alright, that makes a bit more sense. The part about the charger not recognizing it is pretty important. You are manually charging the battery using another battery to allow the charger to sense it. This method is not going to save a battery that has been through too many charge/disharge cycles.

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    rafununugravityisweak

    Reply 3 years ago on Introduction

    You connect 1 dead with 1 which is OK. This one delivers current in the dead one and reactives it, why not ?. A charger won't do the same as it first unload the battery before charging it, it's a very special protocol.

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    yelchuris

    2 years ago

    You guys are really cool(The author and the comments). I had purchased a Panasonic battery pack for a cordless phone.(3.6 V, 850 mAh). After two days of continuous charging the phone also, the pack was showing only ~ 1.3 V or so. I was wondering what happened to this. must be a duplicate I thought. Went back to shop( seller). And he had a fast charger (I think) he had charged it two three times and then it started showing 3.6 right then and also worked in the phone but for short time. He asked me to charge the phone for 6-12 hr first and also use it continuously (charge and discharge cycles). Now I understand the process through this simple instructable and following comments explaining the why a charger may not work at times. I also got lot of help through another instructable about reviving Ni-Cd batteries. Thanks for everybody and for this forum for sharing nice ideas! Have nice time - Prasad

    (the other instructable:

    https://www.instructables.com/id/Bring-Dead-Ni-Cad-... )

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    Durtyoleman

    3 years ago

    Thanks awesome job! I wondered why the rechargables were losing life so soon.