dead or tired ni-cad drill packs

[crazycanuck]

crazycanuck here.
instead of throwing out or moving up to new batteries revieve your old ones .
I work for a battery co. and we do it all the time.
Ifyou are interested its free just anwser this topic.

 

[Deluks]

Go on then. I opened an 18v Bosch Nimh once. I quickly put it all back together again, looked complicated.

 

[Softus]

Do you tease puppies too?

 

[^woody^]

Yes I'm interested in this Lazarus-esq technique.

And probably so are all the bunny rabbits being evicted to make way for new landfill sites

 

[crazycanuck]

glad to see two of you want to save money.
this is not a new process, it was produced for NASA many years ago because thier batteries would not last in space on long missions, the batteries would go dead just like your power drills.
So they came up with a method to revitalize them in space.So having said that lets get started.
First a ni-cd battery cell is a 1.2volt joined together to make the size required. For our purpose we are using a 12 volt dewalt say 1500mah
but the mah is not important. A battery when it gets tired crystals form inside causing shorts reducing power to the point it goes dead,you have to get rid of the short, there is several ways but we will use only one here.
Our 12 volt battery has 10 cells each 1.2volt connected in series ,10 times 1.2=12volt.
unscrew the screws from the case and remove half that fits your charger being careful not to damage cells or connections inside , take note of which is positive and negative terminals.
Now for the list of items you will require for the job.
a digital voltmeter
two 12 volt car batteries
one car booster cable with good clips (only one cable required not the set)
two number 12 gauge wires with clips on one end only, make them one positive one negative or at least mark them so you now which is which,
strip the other ends so you have about 1/2 inch bare
charge you battery in your charger to the best it will charge and take a reading with your voltmeter,we asume this was a dead battery so lets say your voltmeter has a reading of 3.84 volts after charging ,its dead right! WRONG it has those crystals in the way of taking a charge so follow these steps and be amased.
one- with your car single cable booster and the two 12 volt car batteries
connect one end to th positive post on the first battery and the other end to the negative of the second battery.

Two- take the two 12 gauge jumpers and connect them to the batteries,the positive to the positive and the negative to the negative, you should only have two striped ends left don't let them touch anything please
NOW take your power drill reading 3.84 volts and put it close to the jumper leads ,take the positive jumper and hold it to the positive terminal of your 12 volt battery relax nothing will happen until the negative is brought into play .
now take the negative jumper and brush the negative terminal two or three times you will get a small spark at the negative side,
now check yor voltmeter reading you probabaly have6 or 8 volts repeat process until you read 13 or 14 volts you are allowed 10 percent over
put your battery back together and try it in your drill
HAVE FUN post your thouhts when you done

CRAZYCANUCK

 

[Softus]

crazycanuck, no offence meant, but I was interested to see what this all looked like with paragraphs in it...

First a ni-cd battery cell is a 1.2volt joined together to make the size required. For our purpose we are using a 12 volt dewalt say 1500mah, but the mah is not important.

When a battery gets tired crystals form inside causing shorts, reducing power to the point it goes dead. You have to get rid of the short. There are several ways but we will use only one here. Our 12 volt battery has 10 cells each 1.2volt connected in series; 10 times 1.2=12volt.

Unscrew the screws from the case and remove half that fits your charger being careful not to damage cells or connections inside. Take note of which is positive and negative terminals.

Now for the list of items you will require for the job:

A digital voltmeter

Two 12 volt car batteries

One car booster cable with good clips (only one cable required not the set)

Two number 12 gauge wires with clips on one end only, make them one positive one negative or at least mark them so you now which is which,
strip the other ends so you have about 1/2 inch bare.
_________________________

Charge your battery in your charger to the best it will charge and take a reading with your voltmeter. We assume this was a dead battery, so lets say your voltmeter has a reading of 3.84 volts after charging - it's dead, right? WRONG! It has those crystals in the way of taking a charge so follow these steps and be amazed.

1. With your car single cable booster and the two 12 volt car batteries, connect one end to the positive post on the first battery and the other end to the negative of the second battery.

2. Take the two 12 gauge jumpers and connect them to the batteries; the positive to the positive and the negative to the negative. You should only have two striped ends left don't let them touch anything please.

3. Take your power drill reading 3.84 volts and put it close to the jumper leads; take the positive jumper and hold it to the positive terminal of your 12 volt battery. Relax - nothing will happen until the negative is brought into play.

4. Take the negative jumper and brush the negative terminal two or three times - you will get a small spark at the negative side.

5. Check your voltmeter reading you probably have 6 or 8 volts.

6. Repeat the process until you read 13 or 14 volts - you are allowed 10 percent over.

7. Put your battery back together and try it in your drill.

HAVE FUN. Post your thoughts when you're done.

Will this also work with an NiMh battery pack?

 

[crazycanuck]

it may work i have not tried it myself i know lithium ion is out they may overheat and explode

 

[Deluks]

Failed at the first step. I don't have 2 cars.

 

[crazycanuck]

you don,t need two cars just batteries

 

[Softus]

I'm curious - have you tried this yourself?

If so, how successful was it?

 

[Hitachimad]

I read something about zapping them with a welder a while ago...

Chuck in 400amps at 32v... that should sort the little buggers

 

[Paul Barker]

It works on some nicads to flash them with high voltage, but not for too long, let them rest, heat is an enemy, then repeat. Put battery on slow charge afterwards. If it doesn't work you might have one or more dead cells, dead is dead.

To preserve nicads store them discharged , not charged. Try to resist the temptation to charge them as soon as they are flat, bu8t charge them just before you want to use them. Obvioously don't charge them until they won't do sufficient work.

Nicads looked after in this way will outlast in terms of number of charges over their life Nimh and liion.

 

[crazycanuck]

I,ve Done at lest 8 this week for customers including metal hydride all worked well.
As to battery strength, dont use more than twice the voltage of the battery you are trying to fix, I tried to fix a 9.6 with 36 volt one time and got too violant a result.
With the question of who and when you should shock , best resuts are for people who use drill on daily base as this method for those who use a drill once a month or less is not the best ,shocking before use would be the best for them,keep in mind a battery with a dead cell can not be revieved it must be replaced.

For those in the know i am in the midist of building my own battery spot welder my friend has one and it works great. Estimate cost to be as low as 50 Pounds but that is another subjet.