This is a public record of my personal battery tests.  I welcome your input and ideas.  So far, I am having some luck with reviving batteries by surging and freezing.


Updated Jan-02-2011

Surging Batteries

I save my defective batteries in a box.  These batteries will not charge any more and have a voltage of 0 Volts.  A 12V solar panel, which  provides a relatively safe voltage, brought these batteries back up to a normal AA voltage with just a few seconds of surging!


After surging the batteries, as shown in the video above, I looked for an application where I could use just a single battery to provide power.  In order to test the capacity of the reclaimed batteries, it seems best to test each one on its own and not mixed with other batteries.  There aren’t many electronics that use just one AA battery, but here are some:

  • Flasher LED’s
  • Newer LED flashlights  (I don’t have one of these, though)
  • Clocks
This clock uses a single AA battery for power.

This clock uses a single AA battery for power.

I have a couple clocks that each use a single AA battery.  So I popped reconditioned batteries into them and they are working!


The clock above ran on a reconditioned battery from July 8 until August 5, so almost one month.  The interesting point here is that the batteries used to be at 0 Volts and would not charge up, so were destined for the trash or recycle bin.  But after zapping them for a few seconds with a solar panel, the batteries are again back to work doing something useful.

Battery Charging after Surging

The results are not perfect.  I waited a couple days after surging before doing anything with these batteries.  The result is that more than half the batteries went back to 0 Volts.  I believe if I had tried using the batteries or charging them right after surging, the results would have been better.


As shown in the video above, since I waited a couple days before doing anything with the batteries, many of them returned to 0 Volts.  I performed the surging experiment one more time and had much better luck with the batteries, as shown in the video below.


The good results continued.  After most of the batteries charged up, many of the batteries became useful.  I am using some of the reclaimed batteries to power:

  • Wireless headphones
  • LED flashlight
  • Clocks
  • Cordless laser mouse



Surging the dead batteries brought many of them back to life and gave them new purpose.  However, they are not good as new and probably have some issues with charge capacity.  But for me, I’m glad to have many of these batteries back to work instead of sitting in a box as scrap.

——— -

Freezing Batteries

I froze a battery pack and saw the voltage of the pack climb from 6.9V before freezing to 8.4 V after freezing.  I did not surge the pack.  Freezing by itself improved the voltage.  The battery pack came from a Spykee robot.

Related post:  Repairing and Replacing Batteries on a Spykee Robot

It’s OK to freeze NiCd, NiMH, and Lithium batteries. I think freezing disrupts the crystals that are causing the plates to short together. After freezing, hit end of battery with soft hammer to break crystals?  [ Source: ]

It might not work with Lithium batteries [ source ], although Lithium batteries should be safe from damage even as low as -40C [ source ].

Lithium batteries will not be damaged in freezer as long as they are allowed to warm again before use [source].

A well-written procedure:  Hackaday.

Give a Lithium Battery a New Function

My notebook computer uses a Lithium-ion battery.   This kind of battery typically lasts between 2-3 years.  I have one in storage now after it got too weak to keep the notebook powered for long.  Why do Lithium batteries stop working?  Oxidation inside the battery increases the internal resistance. The oxidation builds up over time and eventually, the cell resistance reaches a point where the pack can no longer deliver the stored energy even though the battery may still have ample charge!  For this reason, an aged battery can be kept longer in applications that draw low current.  [ source ]  So, while my old battery pack might not be suitable for the notebook computer any more, maybe I could use it to light up a few LEDs, power a portable radio, a portable media player, or a micro-controller (like an Arduino).  I’m glad I didn’t throw the battery pack away.  I’ll have to try using that battery pack again for a small application.  First, I have to figure out how to tap into the power connector of a Lithium-ion battery.

Store Batteries at Low Temperatures

Lithium batteries keep their storage capacity better if stored at 0°C and at a 40% charge level.  Some reserve charge is needed to keep the battery and its protection circuit operational during prolonged storage.  [ source ]  This means we could store Lithium batteries in the freezer for improved longevity.

NiMH and Lithium Are Different

Lithium batteries do not like to be fully discharged and fully recharged.  They prefer partial discharges with frequent recharges.

Exercising Batteries – My Personal Notes… Work-in-progress (might update later)

Using an Arduino microcontroller, I exercised some batteries by having them turn LED’s on and off until their voltage dipped below a threshold voltage.

Used this NPN transistor:  ON Semiconductor BC547B.  Data sheet:

The BC547B transistor can handle a maximum of 100mA.  The LED’s I’m using fall below this limit, so this transistor is OK for this application.

My red LED consumes 15mA.

Blinking LED takes up to 13 mA

Blue LED:   up to 65 mA

    • Blinking LED takes up to 13 mA


  1. Chris Bodragon says:

    I have been experimenting with surging a Makita 24v battery pack in order to bring it back to life. Surging once did restore the pack a little and surging again, a litle more. Three times and pack was still improving. Having read up on this procedure, I learnt that the surging “shatters” the large dendrite crystals that build up which cause the so-called memory effect. My guess is that because these NiCd NiMh packs contain 20 cells that are connected in series, each surge procedure is restoring the pack one cell at a time. Would this hypothesis have any truth to it? I am midway restoring a pack right now, (10 surges so far, each one followed by a discharge in the drill), and after each surge, there seems to be more power to discharge. Once I get to 20, I intend to put the pack in the charger and see what I get then. By the way, yes this procedure does warm up the battery pack quite considerably but have been very careful to restore the pack to room temperature before going on to the next surge sequence. If this turns out to be successful, I would like to build a semi-auto surge unit utilizing a mechanical car indicator flashing unit along with some sort of electronic timing system that will allow the battery pack to cool between surges, say a 30 minute wait between each surge sequence. Any thoughts, or is this a mad, dangerous idea that I should abandon right now. Thanks in advance. Any comments gratefully received. Chris Bodragon.

  2. Earl says:

    You seem to have experienced some success already with your battery pack. The dentrite crystals, as you called them, might also be broken if you freeze the batteries. Putting the battery pack in a freezer is another option for you. And there should be no danger in freezing NiMH batteries.

    However, in my tests, most batteries did not recover a good charge capacity, as they did when the batteries were new. The voltage of the battery might look good, but its ability to hold energy was diminished. If you are using the batteries in a drill, a power tool that requires substantial energy to operate effectively, you could be disappointed in the battery performance, but I hope that it would work well for you.

    I also had some cordless drills and every battery pack went bad. It’s hard to use a cordless drill without a working battery. I would have liked to have restored the battery packs, and I hope you have good results.

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