Reviving NiCd batteries

[ahofle]

Have any of you successfully rejuvenated or 'zapped' a NiCd battery using the instructions below (or similar)?
http://www.instructables.com/id/Revive-Nicad-Batteries-by-Zapping-with-a-Welder/

I assume these are the same procedures those are constantly trying to sell for $15 on ebay.  Problem is, I don't have a welding power supply, and it sounds like using a car battery would be enough voltage. 
My 19.2V power tool batteries are starting to shorten in charge life.  The thought of buying a new Li-ion battery set for over $50 is not inviting and I would like to try to zap these first.  Any experience or hints would be appreciated.

[patrickl]

Sounds unlikely. The whole "test" looks daft. He zaps the battery and is surprised there is some new power in it after that? Isn't that what charging is supposed to do?

for a proper test he'd need to charge the battery full, show how long it runs till emtpy. Then zap it, charge it to full and then see how long it runs. If there is any improvement then he'd be on to something.

[Kevin Mullins]

I use a car battery charger on batteries that otherwise don't seem to want to take a good charge.
Just a short kick start charge and then put them back on their normal factory charger.

[MonMotha]

http://www.batteryuniversity.com/parttwo-48.htm

That website has lots of useful information.

Sounds like this isn't overly likely to help your dying NiCd tool batteries that are just "worn out", but it could be useful if you had a newish battery and needed some extra torque from your drill.  Sounds like it isn't all that likely to result in killing your battery further, though.

Note that other battery chemistries suffer from other problems and have to be regenerated (if possible) in other ways.  And of course, NEVER play with a Li-Ion unless you know what you're doing.  They are fairly safe when treated nicely, but if you abuse them, they can catch fire (or "vent with flame", aka explode), and the fire is damn well impossible to put out (and whatever you do, DO NOT put water on it).

Just be careful with that cap; it could make your arm feel funny.

[SirPeale]

I tried it and had mixed results.  I could have probably done better but was afraid of blowing the battery up in my face.

Sounds unlikely. The whole "test" looks daft. He zaps the battery and is surprised there is some new power in it after that? Isn't that what charging is supposed to do?

The point of the massive jolt is this: the longer you use NiCad batteries, crystals form within them.  Eventually there are so many it doesn't charge well.  The jolt breaks up the crystals so you can charge the battery again.  A few blows to the battery should do the same, so I've read.

[daywane]

I will let you know.
I have 6 batteries. I know are bad.

I charged them last week. All went dead with in 10 to 45 min.
all take a 90 min charge
most would light up charged in 30 or less min.

I have ordered new ones (well 2 new ones)
here
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=270288662480

I hooked up my car battery charger
 set to start.
reads 10.4 volts
with the volt meter I found - and + on battery, this is a   7.5
volt meter showed 6.v
zapped the crap out of it.
meter reads 8.5 volts now.
charging in charger as  am posting.

these are for a motorola Radius p1225 2 way radio's

[daywane]

so far so good.
been charging for 45 min and still charging.
good going so far

[daywane]

well....light turned green in under 1.hr
 
let me do 1 more and I will take them to work and see if it lasts all day.
I used to get 10 hrs out of em.

I just did 1 more.
batery was a 4 volts. I hit it a bunch of times, went up to 8.5 v.
this one is on the chager now

I was thinking my  battery charger is not stong enough,
so I grabed 3 AA and a AAA batteries. ... Much bigger spark
these are on a 4 hr. charger now.
keep you posted

[RayB]

If you crack open those power tool battery packs, you'll find them full of regular AA  or C size rechargables.

http://www.2coinsperplay.com/Tech/Misc/ShopTips/nicad%20packs.html

[daywane]

my 7.5 volt 2 way radio battery packs are no better.
I think 10+ volts are not enough.

It did work on the AAA or AA battery's

I opened a 2 way radio pack. It has 6 battery's bigger than AA but smaller than a C battery
7.5 volts divided into 6 = 1.25
I will cut 2 packs apart. zap each one , charge each one on my large charger and check voltage
It can charge AAA, AA, C , D, and 9 volt . but it takes 4 hrs and I can only do 4 at a time
If all else fails I can put in regular size AA nickel  cadmium and have plenty of room left over

[Ed_McCarron]

I opened a 2 way radio pack. It has 6 battery's bigger than AA but smaller than a C battery

Probably sub-c's.  Popular size.

I've changed to NiMH for most of my rechargable needs.

As for the LiPO packs - careful.  Use a real charger and a LiPO charging sack.  We've got competitors using them at robot competitions now, where things are likely to get damaged.  We're tossing around purchasing a class D fire extinguisher to supplement a trash can full of sand and 5 lbs of class D powder.