dead batteries revived by new 9V battery

[gene so]

Hello,  I have a portable Milwaukee Sawzall, its works wonderfully when trhe batteries are charged and is useless when they are inert. I have several of these batteries. Eventually they all died. Recently in a passing conversation I was told that with a new 9v battery you used it to jolt to life these old batteries and then they would take a charge once again. Has anybody ever heard of this ? Is there some specific information with this regard that I could download or write down instructions? These batteries cost a lot and I won't buy more so I hope someone reads this who knows this information.  Thank You in advance.

Gene S.

[John Glassey]

50 minutes ago, gene so said:

Hello,  I have a portable Milwaukee Sawzall, its works wonderfully when trhe batteries are charged and is useless when they are inert. I have several of these batteries. Eventually they all died. Recently in a passing conversation I was told that with a new 9v battery you used it to jolt to life these old batteries and then they would take a charge once again. Has anybody ever heard of this ? Is there some specific information with this regard that I could download or write down instructions? These batteries cost a lot and I won't buy more so I hope someone reads this who knows this information.  Thank You in advance.

Gene S.

Hi Gene,

 

while I have never tried it myself, I have seen it done on YouTube videos many times. I do believe it works, I don't know to what capacity the batteries will charge too, that will depended on the age and condition of the battery. 

 

[KnarlyCarl]

Hmm seems crazy. .. maybe I'll do that with my two dead Ridgid batteries. Looks like only with ni cad tho

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[DR99]

You can only do that trick with nicad packs. You can either fry or explode a lion pack.

[KnarlyCarl]

You can only do that trick with nicad packs. You can either fry or explode a lion pack.

Exactly, I know enough not to mess with lithium, and my old Ridgid batteries are ni cad

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[Kato]

I used to use a trick where you'd put the battery in the charger, then pull the plug and plug it back in a few times. It actually worked to revive some NiCads, and didn't hurt the batteries. They were brought back from the dead and lasted a fair amount of time before the trick started working less and less. It worked for my Ryobi batteries, and I've seen YouTube vids where it worked for other NiCads.

 

 

It's worth a try, the worst thing that happens is that your dead batteries stay dead.

[BMack37]

You can jumpstart any battery to take a charge, basically the charger is refusing to charge the battery because it has too little left in the battery and sees it as a bad battery. If you hook up a battery with higher voltage than the current battery they will try to level themselves, so if you are at 0.01 on one battery and 9v on another, they will try to balance at 4.5v across each batteries. This will bring the battery up enough to charge, but it might not fix the battery. If there are bad cells, it will charge but later it will discharge quickly and you'll be back in the same boat rather quickly. I'm sure you've seen this in jumping a car with a dead battery, it will start and you can get to the store but unless you replace the battery, it won't start again without a jumpstart. Hopefully there aren't bad cells.

 

You can also use a DC power supply, but you'd want to hook it up for no more than 10 mins because the battery will explode and can start a fire. This will work on any kind of rechargeable batteries. NiCads are significantly less dangerous. Using the 9V is kind of a fail-safe because it can't overcharge.

 

I've done it with Ryobi Lithium batteries, they ended up having bad cells...as I initially suspected.

[jeffmcmillan]

I've actually done this with nicad batteries and a power supply many times but it only extends the life of the battery since the problems that killed it are still there.  Kinda like defibrillating someone in a hospital, it's not gonna last long unless you can fix whatever caused the problem.

 

Lithium ion batteries are a different story though.  When these go under a certain voltage it causes permanent damage to the battery so if you recharge them the pack could go full hoverboard.  That's why there's a protection circuit to cut out when its discharged and brick the battery if it goes too much below that.  The catch...no one knows precisely when the battery will fail so the protection circuit bricks the battery when it probably still has some life left.  Charge it back up and you might be good to go or might let a lot more than magic smoke out.

[KnarlyCarl]

Just messing around

.

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[BMack37]

You can do it to lithium, you just need to monitor it closely. I've done it, not the way you did...I used a variable DC power supply(while monitoring voltage being drawn into the battery) and monitored the heat of the battery(it never got over 80 degrees). Which is basically how your lithium battery charger works, it applies DC voltage and monitors heat. The thing is, as I suspected with the lithium battery, was that because it was discharged soo badly that it was damaged beyond repair. That being said, it did accept a charge through first the power supply then later the charger. I honestly knew it wouldn't hold a charge but I wanted to do it because I knew I could and kept reading people say it couldn't be done. It actually worked better than I thought, the battery worked fine in the tool until I got bored but wouldn't hold a charge long-term.

 

I don't like going battery to battery, I prefer using even a regular DC power supply because you can easily hook them up solidly and turn them on/off. Sparks are bad.

 

Edit: I think the biggest misconception with lithium is that anything dangerous happens instantaneously, it doesn't...heat first, ignition later.

[John Glassey]

Knarlycarl, nice video attemp on reviving your old Nicads. I wonder how you got that idea?  ?

[KnarlyCarl]

Knarlycarl, nice video attemp on reviving your old Nicads. I wonder how you got that idea?  ?

Oh hey everybody, I forgot to mention the name of the individual who made this all possible - ladies and gentleman, I present to you GLASSEYI!! Haha man yeah I saw the video you put here and thought what better way to spend my afternoon than a cheap science project with tools that I have readily available, and share my experience, maybe will give someone a reason to try their own too.

.

As far as dc power supply goes, that's something I don't have, but who knows, maybe I'll get the chance to use one someday. Interesting results and fun with my tools, that was the biggest factor of doing that video

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[Stercorarius]

Just messing around

.

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I see the sawzall wounds are healing quite nicely. It would be interesting to do you same setup but with a button inline to remove the arc factor.

[KnarlyCarl]

I see the sawzall wounds are healing quite nicely. It would be interesting to do you same setup but with a button inline to remove the arc factor.

Lol yeah I didn't mention that to anyone, but I'm glad no infection set in. If anyone is curious about the three marks on my left hand, my sawzall jumped and stabbed me, bruising as it went and drew quite a bit of blood, never had something like that happen before I was more mad than shocked.

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[MikeInCtown]

On ‎3‎/‎21‎/‎2016 at 9:30 PM, PROTOOLNUT said:

That has got to be the craziest thing I've heard in a while. But whats crazier is the fact that it actually works! Who knew you could restore your dead nicads by doing this? However, when you consider the lack of power these nicad drills have, why would you want to? My 2604 can swamp any of those drills, and race circles around them tons of times, and then eat them up for dinner by the time they finnish drilling a hole ahhhh hahahahahahaha

 

I finally realized this after looking at rebuilding my old Ridgid 12v NiCad packs. I'm like wait a minute, I can get a shorter and lighter 18V drill with 3x the power and I'm looking at making a 10 year old 12v drill work why??? This was even more apparent this last weekend when my brother in law's nicad 18V DeWalt impact wrench wouldn't take the lug nuts off my truck but my brushless impact driver did.

 

This is also part of my reasoning behind starting to buy Milwaukee and stop buying any new Ridgid tools. After 5 years when the warranty expires, I'm willing to bet that anything out there at that time will be far better and more capable than what I am trying to keep running.

[KnarlyCarl]

 

.....This is also part of my reasoning behind starting to buy Milwaukee and stop buying any new Ridgid tools. .....

I approve! Lol

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[MikeInCtown]

58 minutes ago, KnarlyCarl said:

I approve! Lol

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LOL, I think Milwaukee is the only brand I have never owned until now. At one point everything was DeWalt but when they kept wanting $99 for a darn NiCad pack I finally gave up and went with other lines that were cheaper and did just as well. Since then it has been a mix of everything, but with the new Fuel line and brushless technology and now one key, Milwaukee has every tool I would use at work and almost every tool I would use at home. The best thing (I'm sure you all know) is that every tool is available stand alone sans batteries and charger. 2 5.0 batteries are enough for all my needs. In 3 or 4 years when they go bad I'll buy a new combo kit and get a couple more.

 

Anyway, back to the thread, even NiCad or NiMh batteries are expensive these days. Cells for a 12V ridgid pack was like $35 shipped to me. An 18V pack was still like $55 or so. Why bother rebuilding when a good lithium for a couple bucks more will run circles around them and have a warranty. Now, for companies like my electricians and HVAC techs have, since their have dozens of employees who beat on the tools, it may pay to keep rebuilding battery packs.

[DR99]

Yea someone bitched at me on Youtube about the cost of Dewalt Lithium packs verses buying cell rebuild kits for his old nicad packs. It was the TIA video about the Dewalt 18v to 20v max battery adapter.

[BMack37]

8 minutes ago, DR99 said:

Yea someone bitched at me on Youtube about the cost of Dewalt Lithium packs verses buying cell rebuild kits for his old nicad packs. It was the TIA video about the Dewalt 18v to 20v max battery adapter.

 

Some guys refuse to change...normally the same guys that don't understand why milk is soo expensive and why it isn't delivered to their door in glass bottles.

[MikeInCtown]

Hahaha. I pulled out my old Dewalt 18v drill/driver a week or so back to compare size and weight to my newest drill driver. The Dewalt is rated at 400 inch pounds while the new one is 1200 AND it is a hammer drill as well. 1-2" shorter and lighter weight plus it will run 10x longer on a charge. Since I use my tools at work, time is really money, even if I'm on salary. At least I get to leave after 8 hours instead of 9 or 10. It's worth it to have good working stuff rather than sitting there rebuilding battery packs.