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Reconditioning rechargeable NiMH batteries

18 January 2010 6 Comments

What is reconditioning of a rechargeable battery?

Reconditioning of a rechargeable battery is a process by which you regain the lost performance of a battery, If your rechargeable battery is not holding the power it used to you can mostly get the lost performance back by reconditioning the battery (exercise the battery) to restore the optimal performance of a battery, generally NiCD batteries required conditioning with every charge, but it’s not the case with NiMH batteries.

To recondition a battery you need to simply discharge it completely and then recharge the same, you might need to do this cycle 3-4 times to get the full capacity back, or if you have one of the smart chargers that has conditioning / refresh option that you can use that to condition your batteries, do note If even after conditioning your NiMH batteries you don’t get the juice out of your batteries or your batteries seem to not power up your devices as expected or drain out very quickly it might be time to retire the rechargeable battery as the battery might have developed high internal resistance.

How frequently do you need to condition NiMH batteries

NiMH don’t need regular conditioning like NiCD batteries but I have generally noticed that after a dozen or so charges done of a NiMH batteries with intermediate usage or batteries that are stored for more than 6 months the capacity tends to wear off a bit and it’s good idea to condition your NiMH batteries once in about 6 months or after around 12 regular charge cycles to get the most out of them.

I have also found that recondition might be needed more for lower grade cheap non branded NiMH cell. Quality NiMH batteries like Sanyo Eneloops don’t need that much reconditioning compared to low quality NiMH non brand cells, I recondition my eneloops only once is about 20 or so cycles or once per year if they are not used much.

I don’t have a special charger with recondition / refresh / discharge option how can I recondition my batteries.

The smart chargers like La Crosse BC 900 series or the Maha Powerex C9000  chargers that have recondition options like refresh / discharge make it very easy to recondition your batteries but you can also recondition your batteries without these special chargers, to recondition your batteries you just need to discharge them and charge them and you need to do this 3-4 times, to do this with your normal charger follow these steps.

First drain your NiMH batteries completely, a very easy way to do the same, if you have a LED based torch light is tot load the NiMH batteries and switch on the torch light and wait until it it dies, after it dies wait for about 30 minutes and then load these batteries into the charger and charge them fully, repeat this process 3-4 times and your NiMH batteries should  be conditioned good as new.

Do note that you should not use a regular torch bulb incandescent type to discharge the NiMH batteries as it may over discharge the battery below .9V threshold which is bad for NiMH batteries, you can also use a high drain device to discharge the battery.

Also it is a bad idea to condition brand new NiMH cells, brand new NiMH will not give you the rated capacity but after 3-4 cycles of regular usage, they should give you the rated capacity.

Obviously having a charger that supports the reconditioning features makes it a lot easy to condition a battery.


  • Rechargable Battery care and tips - RechargeBatteryGuide.com said:

    [...] of the battery, also do note that batteries which have not been used for a while might require re-conditioning of the batteries to get  their rated [...]

  • How to store a rechargeable batteries - RechargeBatteryGuide.com said:

    [...] will take a couple of  recharge cycles (3 – 4) before they regain their full capacity, a conditioning cycle is a good idea after extended [...]

  • Jessica said:

    Very good article. Clear and straigh to the point.
    Thanks for the info!

  • jay said:

    helpful yes all except for ” by the way don’t drain the battery down completely, when it states leave the bulb on the battery for a half hour after light goes out

  • jay said:

    on the good side this was quite helpful and I was able to spark this no longer available battery back to life THANKS ..J

  • meet said:

    First drain your NiMH batteries completely, a very easy way to do the same, if you have a LED based torch light is tot load the NiMH batteries and switch on the torch light and wait until it it dies

    my question is can i use maglite mini led flash light, plz send me the exact pics of flashlight (mag) which can be used , thank you, nice video by the way.

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