re-liven dead rechargable batteries

[max corrigan]

As the owner of a 24v rechargeble bosh drill with a seemingly dud battery, that won't hold a charge i wondered if anyone had tried this method using a DC welder, it sounds a bit dodgy to me! but just might rejuvenate a very expensive to replace battery unit
Hope i can get the attachment too work (photo bucket seems to have given up on me)
Regards Max...........

View attachment Make Online HOW TO - Revive Nicad batteries by zapping with a ....URL

 

[Bluechip]

Max

This 'method' has been around for years. I've used it by charging a 2200uF capacitor to 3V, then zapping an individual cell. It does sortof work. Have to zap it several times, check cell will charge after each 3 zaps or so. Never tried it with a pack of cells. I doubt if it would work. Pushing a brief high current pulse thro' the non-faulty cells does not seem a good idea.
The success rate I had on a single cell is about 1/3rd. Some cells I've done seem to revive, then fail shortly afterwards.
My 14.4V Bosch pack failed about 3 years ago. New pack £60-ish, IIRC.
New drill, charger, 2 batteries, case was about £89.
Makes no sense! Now I have a cheapo 18V WORXX. Drill, charger, 2 batts. Cost £35. When it dies, it's off to the bin QED.

Dave BC

 

[Blogwitch]

Dave,
Surely you do a stripdown first before dumping, usually a few very useable gears, plus springs and things in there.


Max,

From my modelling days, the dead nicad battery syndrome was a common occurance.

It was caused by things called tendrils growing between each internal cell of the nicad battery, causing an internal short.

Our cure was to 'flash' them.

Connect negative of nicad to negative side of a 12volt lead acid battery, then with a lead coming from the pos end of the nicad, the other end of the lead was quickly 'swiped' across the positive terminal of the lead acid. It usually caused a spark while in the very short contact time, hence the name, flashing. Too long a flash and your nicad pack would start to bulge, and was then ready for the bin. It really was the shortest time you could physically do it in. That had the effect of fusing the tendrils and making them evaporate. It sometimes took a couple of flashes to burn out all the tendrils and get the battery up and running again. You would also find that the flashed battery ended up fully charged, caused by the heavy amperage from the lead acid being transfered across in that very short space of time.

It might be your drill batteries are nicads, and this method just might work. I have never tried it on the later nickel hydride batteries, as I have no idea of their internal workings, they came along well after my time.

Blogs

 

[Kermit]

From the days of the first Ni-Cd batteries.

This works(sometimes) in those cases where a battery, of a certain chemical type, (NiCd), has grown conductive crystals and has shorted out its capacity to charge. The large 'zap' would break those conductive pathways, and let a battery be charged again.

 

[itowbig]

solder two wires to the drill and puit some clamps on so it could be coneted to a battery and use it like that
or strip it down and use the moter for something or u could donate it to me ;D and i could strip it down ha ha :big:

 

[max corrigan]

Thanks everyone for your informative replies, i think i will try Blogs way, it seems less hairy than the welder method!
And itowbig's suggestion of two wires from the drill, is actually being covered in the next "Model Engineers Workshop" be interesting to see if they comes up with same idea!
Regards and thanks Max...........

 

[Metal Butcher]

This is a very interesting thread. I'm surprised that no one has mentioned the danger of this dubious "Reviving the Dead" technique. This reminds me of how Frankenstein brought his creation made of dead parts back to life.

Only this is not a fictional movie!

There is a serious danger of the battery exploding!

I wouldn't try this to save some money! Your co-payment at the ER could be a whole lot more than any potential savings.

Don't tell me Tom, Dick, Or Harry did it and it worked great!

I've had two Ni-Cad's explode and blow the lids off of two different, but proper chargers.

Think about this carefully!

-Rick

 

[shred]

Definitely do not try this with a Lithium-Ion battery. They explode rather dramatically when the least bit provoked. After the metal case pops after being inflated to about 3x normal size by the pressure, the chemical guts of the battery shoot out like a roman candle and try to ignite anything nearby. Fragments of the battery and device can go for 20 feet or more.