# Re-energising batteries



## Smudger (19 Oct 2009)

In between races at Brands yesterday, the conversation turned to cordless batteries and how mine are losing their charge very quickly, is it time to replace them? (And what a price!)
No, said Glen, re-energise them.

He reckons that if I connect the positive terminal to a positive 12v source (like a car battery charger) and briefly strike the negative to the negative terminal 8-10 times it will re-energise the battery. I can then recharge it in the normal way. He says he has done this, and it works, but in this case Mr Internet has not been my buddy and I can't find any references to this.

Does anyone know if this works?


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## woodbloke (19 Oct 2009)

I tried something like this with very limited success...maybe I was doing it wrong  but it didn't seem to work for me. My own view is that once NiCad's start to fade they do so pretty rapidly. I decided to sling my old De-Walt drill as I was getting really hacked off with it so I binned it and got hold of a small Li-ion 12v AEG (as featured in BW) which has proved fantabulous - Rob


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## Dibs-h (19 Oct 2009)

Smudger":3pki4fpl said:


> In between races at Brands yesterday, the conversation turned to cordless batteries and how mine are losing their charge very quickly, is it time to replace them? (And what a price!)
> No, said Glen, re-energise them.
> 
> He reckons that if I connect the positive terminal to a positive 12v source (like a car battery charger) and briefly strike the negative to the negative terminal 8-10 times it will re-energise the battery. I can then recharge it in the normal way. He says he has done this, and it works, but in this case Mr Internet has not been my buddy and I can't find any references to this.
> ...



You haven't annoyed Glen recently have you ?

Rechargeable batteries have been known to go bang! I'd be interested to know the result - 2 packs of my Makita NiMh's have packed up recently. Mind you after around 9yrs life can't grumble. :wink:


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## Racers (19 Oct 2009)

Hi,

Nicads grow whiskers across electrodes in the cell this shorts them out, flashing them across another battery (or I have heard the mains!!!!) can vaporise the whisker and temporality retrieve the battery but it will have left a path for a new one the grow, so it won't last long and you have the danger of explosion. Not something I would do.

Pete


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## big soft moose (19 Oct 2009)

Racers":xmbv9f13 said:


> Hi,
> 
> Nicads grow whiskers across electrodes in the cell this shorts them out, flashing them across another battery (or I have heard the mains!!!!) can vaporise the whisker and temporality retrieve the battery but it will have left a path for a new one the grow, so it won't last long and you have the danger of explosion. Not something I would do.
> 
> Pete



yep i concur - in theory glenn is correct but if you do try this there is a serious danger of bits of chimp being found all over the place 

at the very least i'd suggest you wear a face sheild and gloves but even more so i'd suggest just binning them and buying some new ones - or as rob suggests binning the whole thing and buying a li ion replacement


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## RogerS (19 Oct 2009)

Smudger":23qpu6x3 said:


> In between races at Brands yesterday, the conversation turned to cordless batteries and how mine are losing their charge very quickly, is it time to replace them? (And what a price!)
> No, said Glen, re-energise them.
> 
> He reckons that if I connect the positive terminal to a positive 12v source (like a car battery charger) and briefly strike the negative to the negative terminal 8-10 times it will re-energise the battery. I can then recharge it in the normal way. He says he has done this, and it works, but in this case Mr Internet has not been my buddy and I can't find any references to this.
> ...



Dick...I'm delighted to point you in this direction!

http://www.repairfaq.org/ELE/F_NiCd_Battery.html#NICDBATTERY_004

Reference to 'reconditioning nicads' is half way down.

This excerpt is, to me, worth it's weight in gold as my batteries do suffer from this and so I'm going to try a constant 2mA trickle charge set-up.

_Yes, NiCds have a bad habit of going dead when you just leave them. Fortunately you can recharge them. The current cells discharge about 1 percent a day, maybe a bit less. Expect them to be mostly flat after 3 months. Unfortunately, the so called 15 hour trickle chargers more than make up for self-discharge. In fact most of the current goes to making oxygen, not making up for self-discharge. If you want to make something to keep your cells from self-discharging, make a 1 to 2 mA current source. That should more than overcome self-discharge._

Roger


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## Smudger (19 Oct 2009)

Thanks, all. It looks like the effects, if they work, are temporary at best, and possibly dodgy. So, wait for a special offer and get a new cordless or 2...

Life's hard on pensioners!


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## Dibs-h (19 Oct 2009)

anyone tried opening them up and replacing the cells?


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## RogerS (19 Oct 2009)

Dibs-h":28b8cllt said:


> anyone tried opening them up and replacing the cells?


Theoretically it's possible, I guess. It's a question of getting in a way that it's possible to make a decent fist of putting it all back together. 

Some of the cases seem welded. Also some manufacturers fiddle around with extra tappings or summat as I had two Ferm 24v drills from Screwfix and I know that the batteries weren't interchangeable between chargers even though they would fit and work in either drill. When I opened up one of them I found the 'extra' wire which was a tapping part way down the stack.


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## big soft moose (19 Oct 2009)

Dibs-h":zudlspnr said:


> anyone tried opening them up and replacing the cells?



I did that with the battery pack on my mk1 airsheild, which turned out to just have 3 AA cels wired together inside.

ive not tried it on a rechargeable drill but it ought to be possible


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## paulm (19 Oct 2009)

I've had some batteries re-celled before, so it is possible if you can source the new cells somewhere. Don't know if Maplins would have anything suitable ?

The business I used has closed now unfortunately but there may be others that do the same thing.

Looks like they just prized the cases open and then reglued shut afterwards.

Worked great since and a lot cheaper than the cost of replacements.

Cheers, Paul


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## promhandicam (19 Oct 2009)

Smudger":17ryn21j said:


> . . . said Glen, re-energise them. . . does anyone know if this works?



Dick,

I have some info on flashing batteries (Ni-Cad) - it is fairly straight forward and worked for me. Send me a PM if you are interested and I'll let you have the document.

Steve


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## Racers (20 Oct 2009)

Hi,

I have recelled several battery packs using taged cells from maplins, some just unclip some are screwed together and some you need to crack apart and glue.

Pete


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## superunknown (20 Oct 2009)

I have had this bookmarked for a while that you may find interesting reading...

http://www.instructables.com/id/Revive- ... T#comments


:wink:


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## carpenteire2009 (21 Oct 2009)

You can buy replacement cells from suppliers like www.eurobatteries.com which can then be used to rebuild an old battery. I haven't had to do this yet (my oldest cordless, a Dewalt combi is still running good after 9 years!), but I certainly plan to go this route, especially on a tool that is otherwise mechanically sound.


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