Battery "ressurection"

[uberplasma]

Hey all
I have seen all these ads for restoring or ressurecting old NiCad batteries, like the ones in my Ridgid cordless kits that cost 150 to replace.
Anyone seen or bought these miracle guides? or used the "Revitalization through Vaporization of Dendrites (RVD) Process".?
just wondering

[retiredcaps]

Re: Battery "ressurection"

While researching other things, I have come across a few youtube videos on nicd battery fixes.

I have no idea if they work or not or if they are all a hoax?

If I understand the principle, they "jolt" the dead battery with a good battery so that the dead battery has a minimum amount of charge. That way, the charger doesn't see the nicd battery pack as being dead and can proceed charging.

[Th3_uN1Qu3]

Re: Battery "ressurection"

Vaporizing the dendrites is easy - just take a big power supply and hit the affected battery. Preferably on each cell rather than the whole battery, and use a battery holder so it doesn't burn the contacts on the battery. Safest way to do it is to charge a big capacitor and zap the battery with that. A pair of 10000u 50v caps oughta do it. You'll know when the cells start accepting charge because the sparks will get really really big due to the very low resistance.

Depending on how bad the battery is affected, it could have gone high enough resistance to require pretty high voltage to get significant current to flow and blow up the dendrites. I have a variable output flyback supply that i built, it goes up to 400v and has a 220uF output cap. Some cells didn't start accepting charge properly until i got well over 200 volts. But of course, it's dangerous playing with this kind of thing so stick with the lower voltages whenever possible.

Yes, it works. However, you'll have to use the battery regularly after you've zapped it, or the dendrites will grow again.

[uberplasma]

Re: Battery "ressurection"

Very cool, thanks retiredcaps and Th3 uN1Qqu3. I knew there was at least some truth in it, will try it, just so happens i have a pair of10000uF waiting for thier replacements to arrive so I will begin the ressurection and let you know how it went
Thanks again

[999999999]

Re: Battery "ressurection"

It's not worth the bother, buy new packs or individual tabbed cells (or tab them yourself if you have a spot welder) and rebuild the packs.

The short was caused by a dendrite and putting enough current through the cell will get rid of it, but the cell is going to have many of them that were growing, the one destroy was just the first to complete the short circuit and the pack will not have good capacity or life because the dendrites will keep growing. What constant use does is just keep burning through the new ones but the cell gets worse and worse.

2 x 18V packs are 30 sub-C cells, about $1.50 each with tabs (delivered) on ebay = $45

[kc8adu]

Re: Battery "ressurection"

the only "ressurection" that works is replaceing all the cells at once with new,matched cells.
works every time for me.but costs a bit more since i go with known high quality cells from sanyo,panasonic,ect.ebay china specials are hit and miss leaning towards miss in quality.

[mockingbird]

Re: Battery "ressurection"

You don't need a spot welder... you can sand the surface a bit and regular solder will stick. It's a bit tricky, but it works.

[999999999]

Re: Battery "ressurection"

^ I've done that before, but it does stress the vent seal and I do not trust it for high drain & high charge rate applications where the battery is subject to build up a bit of pressure with temperature change. Better to just get them with tabs, cost difference is small if any and you needed a way to connect them together anyway.

[Th3_uN1Qu3]

Re: Battery "ressurection"

Seconded. Soldering on batteries also takes quite a bite from their capacity - you want your new batteries to behave like new don't you.

[larrymoencurly]

Re: Battery "ressurection"

I thought all Ridgid tools were warranted for life, including the battery packs, unless you happened to buy them during a period several years ago when the warranty had been cut to 3 years. I think Home Depot changed that policy a year later and restored the lifetime warranties.

I found that zapping individual cells with a capacitor fixed them only for a few days, at most. I'd zap the cell several times until the arc weakened, indicating the short inside the cell finally vaporized completely.

I found I could solder cells faster if I first sanded the surfaces and applied rosin flux first.

[brethin]

Re: Battery "ressurection"

Warning #1 Do not use high voltage unless you want to see a nice explosion.

To do this and not kill yourself or make a nice explosion use batteries and not anything pluggged in to a outlet.

I use old 16850 rechargable 4.3v from old dell battery packs that still charge and are good. Alot of batteries from those packs are still 100% but if 1 group in 4 are bad it makes the whole pack bad.

I save and pull those batteries (16850) from Dell Packs and have mangaed to make several handy battery packs for USB drives etc without using Dells controller saying the pack is dead and they recharge fine on any USB 5v.

I use these to run USB drives that need extra power (above what USB provides) and other things like backup 5V gear etc.

I use them to also refresh Vaporize Nicad and Lion cells that fall or show High in my $80 PowerEx smart charger and it recharges them with no issues and they last at least another year or more before I need to do it again.

[999999999]

Re: Battery "ressurection"

^ I used to use am unregulated 12VDC wall wart that had its plug cut off and wires stripped back. Probably has about 1500uF capacitor in it that charges up to about 16V unloaded before the zap, voltage collapses to almost nothing immediately. Sometimes I had to zap a cell more than once but otherwise never had a problem doing it that way except that the cell would fail again soon enough.

[Forgotalot]

Re: Battery "ressurection"

I came across this article and schematic during a web search for the nicad cure. It was from a Mother Earth News article dating way back. From my searches it seems that small short circuits form in the battery which causes it to fail and the idea of zapping it is to burn out those shorts. This appeared to be safer than some of the things I found, haven't built the box yet but it seems worth a try. I have attached both the instructions and the drawing, notice the polarity isn't specifically noted but it seems pretty straight forward. Any feedback is welcomed. Bill

[Longbow]

Re: Battery "ressurection"

the only "ressurection" that works is replaceing all the cells at once with new,matched cells.

Exactly. Like all batteries, rechargeables have a definite life span. Have a look at the real charge/discharge graphs and performance over the life span. Rechargeable battery packs for hand tools are the biggest pain. They are also dangerous to handle. Replacing only 1 shorted cell in a string will not get you a working battery pack because all the others will be on their last breath.

Once in a great while I come accross a new NiCad that is internally shorted. Out of curiosity I connect it to a variable power supply and slowly advance the voltage whilst watching the current draw (keeping it under 3-5 amps depending upon the size of the battery.) Often you will see 3-5 ampere draw at some low voltage, indicating a short. Letting it cook for 10 seconds or so, and standing behind a blast shield, you will often see the current suddenly dive to a fraction of the original. I assume that the internal short has been cleared. The battery seems to work, but I haven't conducted any tests to see how long it will work.

The whole process is just a waste of time even though of some passing interest. And soldering connecting tabs on NiCads is definitely not safe. Replace the battery pack and save yourself a lot of trouble.

[capwizard]

Re: Battery "ressurection"

I used to ZAP NiCad battery with high current and reversed priority, I even drill a hole try to inject some rejuvenate liquid, at the end totally useless.

PS: did anyone cut open the lithium ion battery, take out the lithium roll and put in the water?