# Battery Resurrection



## Joasis

I checked, nothing removed and their feedback is high....I have been getting DC4 kits for $275 and up for a long time, and they are $599 in the stores....


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## gtcway

A google search revealed this site. http://www.batteryuniversity.com/

I also found a couple people claiming that if you have a bad nicad battery, won't hold a charge or sometimes completely dead, they shorted the positive and negative terminal a few times for about 3 seconds each. This apparently gets rid of a crystal buildup in the battery. I think I have an 18v Dewalt battery I can try it on. I'll post the results tomorrow.


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## wsemajb

14.4 volt 2.4mah NiCd Milwaukee. 

Most replacements online range below 2.4mah. Very few are NiMH. My charger is automatic 9.6 to 18volt NiCd/NiMH. Primecell.com will "upgrade" my batteries to NiMH or NiCd to 3.3mah for 56.00 dollars - and shipping will cost me more. Local Batteries Plus will upgrade to NiMH or NiCd 3mah for 54.00 - no shipping of course. I cannot decide, after hours of on-line research, on NiMH or NiCd. Any help?

Lithium will surely be my next purchase, but for the time being, can anyone clear up the advantages of NiMH in a power tool? Is 3.3mah much better than 3mah? Is 3mah (for that matter) much improvement over the stock 2.4mah? Batteries Plus will replace the original 2.4mah NiCd for 41.00 dollars. That's a damn good deal compared to what I've found online. 

One significant factor seems to be temperature tolerance. I frequently work outdoors in Michigan and have heard that NiMH is much less tolerant of temperature extremes.


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## Leo G

First of all you mean 3 AH not 3 maH. But besides that, the NiMH battery doesn't have any memory effect, which means you can charge them mid stream without doing any harm to the batteries output potential. With NiCad you are suppose to drain the battery down before you charge it. Both NiMH and NiCad have the same problem with cold temperatures. The Lithium Ion battery has a much better tolerance for cold but it doesn't take the heat well. The newer batteries have a better heat tolerance than the older.

Going from 2.4 to 3 AH should be a good improvement, not earth shattering by any means but you will notice a longer drive time. Going from the 3 to 3.3 AH will be noticeable if you compare them side by side, but you may not notice the difference in the field. Get the NiMH unless you plan on switching over the the Lithium Ion soon.:thumbsup:


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## wsemajb

just following up. 
My charger has a 2.7amp output. Does this mean that (unless I purchase another charger) any rebuild over 2.7ah cannot be fully utilized? I realize that there are no NiCd cells over 2.4ah at this time.


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## mdshunk

wsemajb said:


> My charger has a 2.7amp output. Does this mean that (unless I purchase another charger) any rebuild over 2.7ah cannot be fully utilized?.


Nope, that's just the "rate" of the chargers output or how "fast" it charges. A 2.7 ah charger will take slightly longer than one hour to charge a 3 ah cell.


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## wsemajb

Thank you very much Leo G and mdshunk. I think I know what I need now.


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## delous

*fixed my batteries*

All right after reading up and looking at this. I went to my garage. plugged my trickle charger in. connected the positve lead from the trickle charger to the positive post of my 18v craftsman dead for the last 6 months battery. Then connected the negative lead from the trickle charger to the handle of a rough file. Connected another wire to the negative post of the craftsman 18v dead for the last 6 months battery. And completed the circuit down the rough edge of the file. (rubbed the bare wire from the 18v down the file,this broke the contact and recontacted several times). Now before i did this when i would put it on the charger it would say defective battery. After 5 minutes I put it on the charger and it charged up. Amazing for it being dead for 6 months. I did put it behind a tool chest in case it went off LOL, but all is well.:clap: not here much but do check email, [email protected] for questions


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## phil37

*Resurrecting DW9091 batteries*

I too searched all over the net for a solution to the problem, of dead cordless batteries. 2 or 3 days ago, I had at least a half dozen that were stone cold dead. I read the last post in the forum and thought, "why not?". At first , I was disappointed. It made the Dewalt charger recognize and charge the batteries, but the results were less than stellar(6.9 volts max). So I figured I would try something a little bit more aggressive.
Warning!!!! Warning!!!
This worked for me, but I was VERY careful, using long leads and a toolbox for a shield(initially).
I made up a long jumper wire set and hooked the DW9091 up to my roll around car charger on the 12v 200 amp boost setting. I hooked up my multimeter to the battery, and then plugged it in, after having set the switches on the charger( a poor man's remote control). I watched the meter rise for 10 seconds, then unplugged. The battery went to 10 volts, but quickly discharged. I then tried 30 seconds. Up to 12 volts then rapid discharge.
I finally let the multimeter be my guide. The setting that seems to work for me is 18 volts for at least one minute. The best results I have are to leave it at 18 volts until I detect the first sign of warmth. then unplug. Let it cool for an hour, then repeat. I now have a bunch of 14.4 batteries that have held at just under 16 volts for 2 days, and in 3 of my 4 DW996 drills( the other may need brushes), I cannot hold the chuck in high or low gear.
Someone might say that this was foolish, but I am glad I don't have to pay the tariff for new batteries for a while. 
Use this method, or don't. It's up to you. But it worked for me.
Just be careful, and under no circumstances should you leave the setup unattended. Some get warm faster than others, but they are all still holding a good charge, and the Dewalt charger will now charge them to around 16 volts. 
BTW, it's also a "poor man's" quick charger. Fully charged batteries in less than 2 minutes.
Good luck!


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## mickeyco

I'll add something, if you are rebuilding or repairing a battery pack, make sure that all the batteries are at the same charge level. If you have a bad pack and put in one battery that is fully charged and the others are only half charged the electronic battery chargers will not fully charge all the batteries. It's best to discharge all the batteries to the same level with a resistor or flashlight bulb, when they are all at the same level they will charge better and last longer


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## andrew07

mdshunk said:


> If the manufacturers would make a charger that had a button you could depress to start the charging of a pack once you plug it on, we'd all get much longer life out of our batteries.
> Hope this helps.



I have buttons on both my 24 and 18V Dewalt kits, this isn't what you are talking about is it? It says to press the button and charge this way about every tenth use.


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## sparkysteve

I had some rebuilt at a local "Batteries Plus" for $50 each. They died in less that 6 months. Now I just buy new ones.


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## bugsy151

*DeWalt 18v Li*



mdshunk said:


> I've got too much of an investment in the 18V system. With 4 normal trucks, and 4 batteries on each, that's 16 batteries. That's a dandy chunk of change. Not to mention all the tools that would need replaced to switch to 28V. I assure you, though, that we will slowly switch to 28V as tools die.


In a very cool move, DeWalt released their new line of Lithium Ion batteries whose 18v version will fit and run all of their 18v tools. No need to upgrade all your tools (two XRP hammer drills and an XRP sawzall for me) just buy the new batteries and charger and you're good to go!

Way to go DeWalt!!!!!

BTW, for those who are 'shocking' their NiCads back to life, be VERY careful (especially if you are using a 200 amp charger) as they can explode due to excessive heat. We've found that this is a temporary solution at best and simply puts off the inevitable reality that you'll either have to rebuild the pack or replace it.


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## jiffy

I suppose it is cool in a way that Dewalt has made their new li-ion battery work in the old tools. They did it to sell you a new system too. New charger, new batteries, etc. for your old tool. I would think it to be best to have a tool designed for the new battery they have. 

I haven't found anyone that has had good success with getting batteries re-charged. The "recharged" batteries seem to last an even shorter amount of time than the original.


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## al10fred1081

as posted above ridgid batteries are free for life.......... I use the lithium 24 volt system. I don't think its got as much run time as the milwakee 28v but still outruns the charger. meaning I only need two batteries... but I have a tool buying disorder.... so I have four. The cordless sawzall is the only tool I use that will kill a battery before the other one is done charging.

Alex


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## uruiamme

*Safer than Jump-starting*

*The technique of jump-starting a battery with a auto battery charger does work, but I have to pass this along. I have a little background in electronics, so although I never read the "resurrection" guide, I had a hunch how to fix some dead batteries. My experience was with some Craftsman 19.2V Diehards, but this will work for any Ni-Cad.

I noticed that some batteries would lose a full charge and go down to 0V or they would even reverse polarity! Bad news. (Like when you leave a flashlight on for a week.) The charger would of course refuse to do anything. It has a defective LED, but I have never seen it on even with these duds. So I figured that once I charged these dead ringers a little, the regular Craftsman charger would kick in. Sure enough, this is exactly what happens...

I found two old wall-wart power transformers, each with 12VDC output. I checked their polarity, cut the wires, spliced them, and made a powerful 24 volt (usually about 30V unregulated) quick charger. This setup will not put out more than a trickle... sort of like using the trickle charge on a big charger... but perhaps even less. I think my wall warts were only 500 or 1000 mA, so this is relatively gentle in comparison to a 2/10/30 Amp... and it can also be used for more than just a 12V charge.

So I would watch voltage as I juiced them up, and go ahead and do a pretty decent charge to near where it should be, but without good clamps or alligator clamps this is tedious. In many cases, this will save the $60 or $70 replacement charge of a known good battery. Just watch voltage during charge and get it to perhaps 1 or 2 volts over nominal. And then try the regular charger after the battery cools if you charged it long.

If your battery is aging, then some of the other tricks I know are to do the old "discharge" trick which others have mentioned. You can put the battery on a light, drill, whatever, but I don't know about shorting the terminals. Sounds like bad advice, but it may work for some things if you don't let it heat up, bubble, and burst in your face.

If you have a bad cell or two or three, then what will happen is that as soon as you put your apparently charged battery into something, it will last only seconds. The other way to tell is when your super-charger or your regular charger is done, then the final voltage of the battery pack is way below its rating, like 9V. Toss it. Well, after you check for bent terminals.

And as for cooling them down, I have tried throwing them into an ice chest, but I sure wish I had always done this using a ziplock bag... Nothing like getting water inside... duh. But the ice works!

And for Craftsman, I will say this: buy the extended warranty, and find a friendly store to take back the entire set. Just offer blank stares when they wonder how you got all that sheetrock dust on the sawzall, or all the paint on the drill, or how the batteries got all the dents.
*


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## vital151

i went through 4 dewalt 18 volt batteries in the last 6 months. does anyone have the same problem? my ryobi bateries are over a year old and are still working great


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## MDShinn

*proper dead battery use*

I buy new batteries right away....... as a result of me throwing the old ones at my ex-knife...... I mean ex-wife.

I don't miss my ex-wife much, my aim is improving


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## bonnie scotland

MDShinn said:


> I buy new batteries right away....... as a result of me throwing the old ones at my ex-knife...... I mean ex-wife.
> 
> I don't miss my ex-wife much, my aim is improving


did you not try some of the recharging techniques on the wife before you discarded her :laughing:


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## MDShinn

*I didn't think of recharge.......*

but I did get a charge out of it

"Women, as some witty Frenchman once put it, inspire us with the desire to do masterpieces, and always prevent us from carrying them out" 

Oscar Wilde


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