Don't throw away cordless drill battery yet until you try this

[kyle4501]

I have 4 18V De-Walt Ni-Cad batteries that won't hold a charge & after overnight in the charger have anywhere from 3 to 8 volts.

I used my MiG welder to zap them & voi lah, 18+volts 

So I put one in the charger & wait for the light to go off indicating full charge. I check the voltage & it has dropped to 16V (a good battery comes out at 18+V)

I charge another & same results & the first battery is still dropping voltage.



Result = no on the free lunch! 


Cute idea, but empty . . . . .

Now I have a question - Why would someone post that when he had to know the results didn't last?

OR- am I the only one with dud batteries that won't behave?

[Stormcloud]

I have done this on several occasions on NiCad batteries using an auto battery as the source.
Worked 'almost' every time. The 'almost' battery was plenty old and had been dropped a couple of times 
I replaced all the sub-C cells in that battery pack and ....good as new.

Ditto on the relocating the 'thermonuclear devices'.

Mark

[kyle4501]

Well, I'm 0 for 4 

At least it didn't cost me anything. . . .

[bobofthenorth]

If you haven't thrown the batteries out yet Kyle, my good friend Vic Allen taught me how to do this but I use a heavy duty battery charger (boost charger).  It needs to be something that will build around 18V open circuit.  Hook it up to the dud battery and leave it on for 15 - 30 minutes.  I judge the time by how hot the battery gets.  It doesn't always work but it does work often enough to be worth trying. 

Vic had regulated power sources so he could do bigger batteries - for me it only really works on 9 volt batteries because all I've got for a power source is my battery charger.  Vic isn't with us anymore - his all too brief retirement got cut off by a 2nd heart attack 3 years ago now and there aren't many weeks go by that I don't think of him in some context. 

[Don4107]

Better if you can take the pack apart and only zap the shorted cells to burn off the short without hitting the good cells with the current.  No worries about blowing internal fuses.  Alas, many times it is a temporary fix.

The best fix is to avoid the short, not that you can in all cases.  When you start to feel the pack going down STOP.  Never drain it all the way.  What is happening is one or more of the cells have less capacity than others.  Once that cell goes to zero volts continued use of the pack reverse charges the dead cell/s.  Sure way to kill the pack.  Don't overcharge (hot), don't over use (hot), don't delay charging a dead pack.

Am I the only one that noticed the contact glowing red when he hits it with the welder.  A battery charger is much safer and if dealing with individual cells overcomes the problem of higher voltage packs.  A quick spark is all you want.  May not burn the short off as well as a welder, but much more controlled.  Stay on to long and you had better have the safety glasses on.

Now, if you know how to get some of those packs apart, how about sharing it.   My solution is a cutoff wheel and ShoeGoo. UGH.

Don 4107

[Sojourner]

I have 4 18V De-Walt Ni-Cad batteries that won't hold a charge & after overnight in the charger have anywhere from 3 to 8 volts.

I used my MiG welder to zap them & voi lah, 18+volts 

So I put one in the charger & wait for the light to go off indicating full charge. I check the voltage & it has dropped to 16V (a good battery comes out at 18+V)

I charge another & same results & the first battery is still dropping voltage.



Result = no on the free lunch! 


Cute idea, but empty . . . . .

Now I have a question - Why would someone post that when he had to know the results didn't last?

OR- am I the only one with dud batteries that won't behave?

Kyle...I too have 18v (5) but not yet done it....my welder is over 500 miles away. My thinking that the welder is only about 16v. In the "youtube" demo using 12v or 14v battery.
I having done any study yet about the reason of what is taken place to get the battery to revive.

So now reading your result is telling me something. Thank you very much.

Still like to hear other but nuts results.

Sojourn for Christ, Gerald

P.S. Bob...Don't give up...hang in there, we will get the needed information to start saving cordless battery.

[kyle4501]

my welder (millermatic 172) put out 30V dc

I was using .030 wire & it did not heat up like the one on the video.

[boogiethecat]

What's happening here guys is that as a NiCd battery gets old it grows little microscopic needles on one plate that stick thru the electrolyte and touch the other plate, creating a resistance path (a "soft" short) that kills the battery. At least that's the theory I heard when I started doing this almost 30 years ago. So when you come around and put a massive current thru the battery, those little needles get burnt away, literally, and the battery comes back to life.  It worked almost 100% of the time for me, over hundreds of batteries.

That said, there's a major difference of what the video says and what the "real" way to do it is, and this is probably why some of you are seeing no-go's.
AND the video gives very dangerous information...I wouldn't do it.
  I'll explain.

First off, the way this SHOULD be done is to put a massive BUT CONTROLLED current thru a CELL until it's charged somewhat, and then short it out till it's dead, then do that 2-3 times.  Not just hit it once with some unknown big current and that's it.
That's one big difference.  Another very important difference is that you kinda have to do this on INDIVIDUAL CELLS, not the whole battery at one time.  Reason? In a stack of batteries, it's very likely that one or two of the cells within are screwed up much more than all the others.  If you do what the guy in the video says, you've got a few cells with low impedance and a few with higher impedance, and in simple terms this will hinder the possibility of getting the energy where it needs to be, and allow much more energy to be absorbed by some of the cells in the stack than others. Because of this some of the cells within the pack are "revivied" very unevenly, if at all.

Last, the current should be controlled or you're looking at some severe safety possibilities, like kaboom.  I guess an arc welder controls the curent to some extent.  I was instructed to use a current of 10 times the amp hour capacity of the cell... ie if it's a 3500mah cell, use 35 amps, no more, no less.  So at least I think an arc welder would be ok as long as you can control fine enough to not exceed this formula, but it's not my choice.  Using a car battery is insane as there's absolutely NO way to control the current.  FWIW I used a variable DC power supply that has an amp meter, and that's the recommended method... you simply hook up the cell, turn the voltage up until the cell is drawing whatever current you want, feel the cell and watch the meter.  The current varies all over the place as the cell responds, and often times I had to "ride" the voltage knob to keep it in check.  You can't do that with a welder....

So here's how I did it, and it always worked...

Take the battery pack APART so you can get to each individual cell within it.  Apply high current to the cells, one at a time, until that cell gets warm, which usually takes only  10-30 seconds.  Let it cool for 10-15 minutes, then short it out for 5 seconds or so (this can cause very high currents so watch it, you could burn yourself with whatever you're using to do the short).  Repeat 2-3 times.   NEVER allow a cell to get warmer than you can hold on to.

Doing this properly takes a lot more time, requires taking the pack apart, and may not be practical, but if done this way it's safe and it works.  Also, you will occasionally find a cell within the pack that will NOT repair, and doing it this way, it can be replaced.

In my humble opinion, doing a whole pack at a time is not effective for a lot of technical reasons, it's not safe by any stretch of the imagination because you have NO idea of the temperature of the individual cells inside, and it's kinda stupid to try it that way. 

Sorry, it does work but it's just not as easily done as the video shows, and to me this video is a great example of the fact that "everything you see on TV" is not necessarily good information.  The guy took a sound technique, did not research it, and provided the world with a dangerous, stupid version that shouldn't have been put out there.

If I were you guys, I'd quit screwing with NiCd batteries in the first place.  Take the pack apart, toss the Nicd cells to the recycler and replace them with NimH cells.  That way you have a great pack that will not get a "memory". It'll last a long time, and it'll work with the same charger, because Nicd batteries and Nimh batteries are identical in their charging needs.
Granted this might be beyond your capability as it probably involves finding the right Nimh cells, taking the pack apart, spot welding or soldering in the new cells, and getting the pack reassembled without destroying it... it's not a particularly easy job.. but I've done this more than once and am quite happy with the results.  Nicd batteries are a thing of the past, toxic as hell, problematic, and generally better to replace, at least in my opinion...

Wheeeeee

G

[kyle4501]

Ahhhh, Finally, a reality check for one more instance of junk science        (for those watching the OT )

[Bob Belter]

Ahoy, BusFolk,

'Just did that ---  I have four Dewalt 12vdc battery drills, plus ~~10 batteries.  I considered going to the 18 or 24 vdc items, but these are light and handy and paid for.  If I need more power, I plug into the wall, and then I have the electrical resources of the entire nation available to me.

I recently installed new 3500 mAh batteies in two of the battery packs.  You have to cut them open with an air saw, solder the tabs, and stuff them together and glue them with ABS cement.  They really work GREAT, with near twice the mAh rating.  There are now 4500 mAh batteries available.  You can buy new ones for little more $$$, but man, do these ever have 'soup'.   BTW, do extra insulation where the + tab crosses the case.  The existing plastic insulation is very marginal.

I tried the 'zap' of an old 'weak' battery which I have, which I was still using.  Fully charged, tied the trigger down, and it ran for ~~ 2.5 minutes.  I zapped it with my Lincoln mig, ~~31 vdc for several hits, maybe 15 seconds.  Recharged it, and same drill, battery, ---all the same --- ran for 16 minutes!!!! Not bad!!!

This scheme really works!!!!

Enjoy  /s/  Bob