I'm interested in experimenting with trying to revive some old NiCd batteries by zapping them and I ran across this on YouTube. Good, clear video about using two other good NiCd batteries to revive the dead one.
I wonder if it works how much more life you get out of them. I saw this a while back when I had a driver/drill pack that went bad. Finally decided that for $20 I could get new batteries on Ebay and just rebuild it.
What the OP is talking about is using a low-impedance power source to burn open the whiskers that sometimes form on older NICAD batteries, especially when they are left unused and uncharged for long periods of time. Once the cells start whiskering, they almost always are prone for it to happen again, the best thing to prevent/stop this is to keep them permanently on a trickle charger. I have some very old nicads, perhaps 30+ years old, that I still use in some tools that I keep on trickle chargers. I know I am using power to keep them charged, but the convenience of always having the tools ready when I need them outweighs the small cost. When they were new, they were very expensive so that is another reason I hate to discard them.
The trick that people used in the olden days was zapping them with a big capacitor. You charge it up to the battery voltage or a little more and then discharge it across the battery (plus to plus). Do that a couple times and it blows the internal shorts out. (small hairs grow between the elements) The down side is if the battery pack has a fuse, you probably blow the fuse.
I have also heard of people doing the same thing with a car battery but the down side of that is that the battery pack can blow up if there are to many internal shorts.
car batteries plates are consumed and fall apart after awhile, you might get a shorted cell once in a great while but the vast majority of car batteries plates just disengrate
ZAPPING a nicad just burns off the metal "needles" or "tendrils" that are shorting out the cell. The battery works untill the burned off tendrils regro, shorting the battery again. This may be hours, weeks, or months - then you have to do it again. A BIG capacitor, charged to a voltage at least 4X cell voltage, and discharged across the battery usually does the trick - just a couple of similar batteries MAY, but I would't count on it as their internal resistace may be high enough to limit the current to a level too low to do the job. You want to VAPOURIZE the little suckers.
Actually I've read just the opposite. That leaving them completely discharged is the best way to store them.
He's refering to USING the car battery to zap the nicad, not trying to restore a car battery.
In message , RicodJour writes
I momentarily splat my whiskered-up nicads (preferably individual 1.2V cells) for around 5 seconds with a 'pokey' 12V car battery charger. The
20A ammeter rattles on the end-stop. The battery gets hot, so caution is advised.The next step is to measure the short-circuit current (typically over 5A with an AA cell), letting the current drop to near zero (it usually only takes a few seconds). Next, I measure the voltage. If the battery is recovering from the short circuit (voltage rising slowly), then the whisker has been successfully vaporised, and it can be given a charge. If not, I try a repeat zap or two. If still no go, the battery gets marked for 'green' disposal.
I've got a few surviving batteries which are nearly 30 years old.
I THINK he meant using a car battery to ZAP the NiCad.
According to Panasonic, storing NiCads should be between 10 and 30 degrees F, and charged at least once a year. Never store the battery dead. NiMh batteries are a different story and can be stored long-term either dead or fully charged, According to both Sony and Duracell you may need to "reactivate" them by charge cycling - long term storage between -20 and +35 F, 50% RH.
DO NOT store dead with a load connected.
And here's some sources that say they should be stored discharged:
I would trust Panasonic more than some web site
I was talking about using the car battery to fix the nicad
Sorry i miss toook what you said:(
But nicad cell wear out too, one failure must be shorted cell, but nothing lasts forever:(
A local tool store had a big business going for awhile, apparently zapping battery packs. Ther business ended as people lined up for refunds....
Some website? One of those 3 websites was a tech data sheet from a $750mil manufacturer that gives a tech data sheet on storage for nicads used in aircraft. I think they would be considered a credible source. And they clearly say to store them fully discharged.
As for Panasonic, what you are apparently trusting is the previous posting of heresay regarding what Panasonic says or doesn't say on the issue. Many times people read what they want to read. If you have a link to what Panasonic actually says, or anyone that says they should only be placed in storage fully charged, I'd be happy to see it.
There is a big difference between consumer "dry" Nicads and aircraft Nicad batteries. These are vented, flooded cell batteries - like the lead acid automotive batteries of 20 or so years ago (and many up to this day). Totally different than sealed "dry" cells
As for Panasonic, see:
te:
You do realize that both don't count when one is just repeating what the other says, don't you? I agree that Panasonic is saying to keep them charged when in long term storage. There are plenty of other sources that say the opposite, to keep them discharged and I've also seen others that say it doesn't matter one way or the other.
Here's a competitor to Panasonic that says to keep them discharged:
I'm not saying which way is right on this. Only that there are differing opinions. It may also have something to do with the particular battery manufacturer's exact process and what company A says for their batteries may not apply to company B's. In my own case, I just don't worry about it at all because I think in the grand scheme it probably doesn't make much difference.
And PowerSonic does not differentiate between NiMh and NiCad batteries anywhere on page one..
There are also other references that talk about storing Nicads shorted (obviously totally discharged first) - but they all emphasize that EACH CELL MUSTBE SHORTED SEPARATELY - meaning you cannot short a nicad BATTERY (or pack) - only a NiCad cell. Apparently a shorted dead cell does not grow the cadmium needles like an open circuit dead Nicad does.
Say what? As usual, you love to just make stuff up as you go. PowerSonic says nothing about each cell having to be shorted seperately in their battery manual. And if that were necessary it would obviously be pointless to put the statement recommending Nicads be stored discharged in the front of their technical manual that applies to all their batteries. How many of the batteries in that manual are single cell? Probably either none or almost none.
One of the two references you provided previously, that recites what Panasonic says, follows that with a quote from another source that says that Nicads can be stored either charged or discharged with no damage.
I'm inclined to think it doesn't make much difference whether you store them charged or dischaged because if it did and storing them one way or the other made a big difference I would expect it would be easy to find lots of consistent info from most sources. Including right on the battery packaging they come in, yet I've seen no such info. One thing is for sure. Storing them either discharged or not doing anything is a lot easier and practical than Panasonics recommendation to keep charging them every 6 months when in storage.
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