Bad battery or bad charger?

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  #1  
Old 10-31-05, 12:46 PM
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Bad battery or bad charger?

I've had a Dewalt 18v 4 tool kit for a couple of years now, and recently the batteries can't keep a charge. When I charge the batteries they only will work drill or saw for a minute or two when they used to last quite a while. Do the batteries "wear out" after a while and need to be replaced? Or is the charger bad?

Thanks
 
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Old 10-31-05, 03:26 PM
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battries do need to be replaced , two years is a resonable life . the higher voltage ones dont seem to last as long as the lower volt.
 
  #3  
Old 10-31-05, 03:36 PM
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DeWalt recommends leaving the battery on the charger overnight every once in a while. If that doesn't help, time for new batteries.
 
  #4  
Old 10-31-05, 04:00 PM
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Originally Posted by chure
I've had a Dewalt 18v 4 tool kit for a couple of years now, and recently the batteries can't keep a charge.
Sounds about right
If I get over two years out of a battery I'm happy
Well, not happy
But that's the way it goes
 
  #5  
Old 10-31-05, 04:29 PM
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I think Greg has a link to a pretty good article on batteries maybe he will post it again
 
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Old 11-01-05, 06:20 AM
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Thanks all, that's what I thought. I also just read that extreme heat and cold and are not good and I've been storing the tools and batteries in the garage for the last 9 months. I probably should bring them in the house.
 
  #7  
Old 12-08-05, 02:22 AM
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Rejeuvenate nicads??

Someone suggested - either on this forum or the UK (Screwfix) one - cant remember - to put dud nicads in a freezer for a couple of days then recharge. I havent had to test this out tho!
 
  #8  
Old 12-08-05, 12:40 PM
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It will take some doing, but you can repair cordless drill batteries. An 18 volt battery pack is made up with 12 "C" sized rechargable cells. These are available at Radioshack or any place that sells rechargable batteries. After your battery pack has been on the charger long enough, take the cover off the pack and identify the positive end of the first cell in the chain. Using a multimeter, check and make note of the voltage reading between that point and the negative end of that cell and then from the negative end of each cell in sequence. From cell to cell you should see a 1.5v jump. If the voltage jump is less than .8 volts, the cell your checking is bad. Mark the cell and keep checking the cells until you get to the end. You will probably have to cut or de-solder the leads going from cell to cell to beable to extract the bad cells. Be certain, when putting new cells back in, that the polarity is correct. Again, you will have to solder the leads back on. Warning, this can be tricky.

I just ressurected a pair of 12v DeWalt batteries ($56 each new) for $9 in rechargable batteries and an afternoon of fussy work. For me, being a cheap S.O.B. who likes fixing things, it wasnt so bad.

If a battery pack is allowed to go very dead, the cells holding a higher charge will actually start recharging the weakest cells and reverse the polarity of those cells. For my 12v Dewalts (9 - 1.5v cells) having 3 bad cells each, it meant that I wasn't even getting the benefit of the remaining 6 good cells, because they were giving up their charge to the the three bad cells with reversed polarity. Essentially I was only working with 4.5v of power.
 

Last edited by imagineer; 12-08-05 at 01:20 PM. Reason: more clear info
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Old 12-29-05, 05:15 PM
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Then how do you re-seal the battery pack without buying $12 worth of epoxy plus the batteries, etc?
 
  #10  
Old 12-29-05, 05:33 PM
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how many of the 9 cells did you replace ?

I would expect the others will die off a few at a time

if you have lots of time on your hands this might be ok but dont fool yourslf into thinking you will get $56 battery life /preformance for 9
 
  #11  
Old 01-03-06, 11:57 AM
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Sealing? I was able to open the packs by simply removing 4 screws. I suppose, if necessary you could glue it back together. When I had to cut open the charger for the DeWalt to replace a blown fuse, I just wrapped it back up with black electrical tape. It's been over a year since the repair, the charger still works and the same tape is still holding it together.

On my DeWalt 12V batteries that were repaired, each actually had 10 1.2v cells. Of the 20 total cells, only 14 were any good (and several of those were marginal). I bought the 6 cells I needed at Radio Shack for $9 or so. I could have spent about double that for better batteries, but got the cheaper ones so the amp/hours per cell matched the ones from the packs. I should add that 4 cells were bad in one pack and 2 in the other. Before putting the whole mess back together, I moved a few cells from one pack to the other to balance out the potentially weak cells.

I figure I can do the same repair again in a year or so and still be at less than half the cost of one new 12v battery. And for Mango-Man, I'd estimate the repaired batteries last 85% as long as when they were new.
 
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Old 01-03-06, 04:58 PM
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I have to admire anyone who tries to combat the ridiculously high prices of DeWatt batteries.
 
  #13  
Old 01-03-06, 09:26 PM
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Heh Heh! Amen, Lugnut!

I recently tried imagineer's advice and took apart a bad 14.4 battery pack. Once I had it all apart I figured I'd stick it on the charger one last time to make sure it would give me the rapid blinking "replace pack" sign. Oddly enough, it made this high pitched jet engine type whine for just a second (I thought it was gonna blow!) and then it charged just fine! What luck! So at least one of them has been resurrected for the time being.

Now if we would just get a blizzard, maybe I'd have time to try my hand at 2 old 18V batteries. I doubt I'll be as fortunate with them. They had a good 3 years or so before they bought the farm. They pretty much do what you mentioned, Chure- they only take a minimal charge. My batteries probably got roasted in my cube van during the hot summers here... I bet it gets over 140F in the back of that thing in the sun. But what are you gonna do when you work when its hot out, work when its cold out, and Dewalt recommends the batteries stay between what? 100F and 20F? I wish!

Oh, one other thing I was going to mention... I have a DeWalt battery pack that IS malfunctioning... it's empty, but it acts as if there's a battery in it... blinks like its charging, then blinks fast. I wonder if it's because I got it wet last week and now it's either frozen or still wet. I suppose I should bring it inside where its warm and give it a chance to dry out. Any ideas what to check if this doesn't help?
 
  #14  
Old 01-04-06, 06:45 AM
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Originally Posted by XSleeper
Oh, one other thing I was going to mention... I have a DeWalt battery pack that IS malfunctioning... it's empty,
Empty, as in, no stuff inside the plastic case? If so, I'd guess the reason the charger behaves the way it does is due to a feedback loop built into the charger circuit. Most chargers use a comparitor IC chip (LM339 or something similar) to "compare" the amps (or volts in some situations) being drawn by the charger as opposed to being drawn across a feedback loop. The feedback loop, probably a diode biased resistor, will draw only minimal amperage, similar to what a fully charged battery would draw. As long as the battery is drawing more current than the feedback loop, the charger will indicate a "not done yet" status. When the comparitor chip senses the amps (or volts) at two leads, one from the battery and the other from the feedback loop, being near the same value within a preset range, it flips a logic switch on the chip, triggering the "all done" blinky light. Look inside your battery case and see if there is a small gray diode connected between the battery contacts. If so, thats the bridge for the feedback loop. A fully charged battery will draw only milliamps, thus hardly no volts, so a trace voltage can seep through the diode against the bias, providing a signal to the comparitor chip.
 
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Old 01-04-06, 07:48 PM
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Empty as in, the battery charger is empty.

It does not have a battery in it, but it is acting like it does. You plug it in, and it actus just like it would if you would have plugged it in and stuck a battery in it to charge- it starts blinking like its charging. And if you push the little "tune up every 10th charge" button, it acts the same way- as if there was a battery installed.

I bet the rain the other day fried something in it.
 
  #16  
Old 01-04-06, 08:49 PM
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Yep, it's toast. Although my earlier boring long winded diatribe offered to those willing to read it a glimpse into the magic little box that works not nearly as fast as any of us would like, it won't help you. Sorry.
 
  #17  
Old 01-04-06, 10:34 PM
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LOL, thanks.
 
  #18  
Old 01-11-06, 03:41 PM
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Getting into a Dewalt 14.4V battery pack....

Like imagineer, I have repaired many a NiCd battery pack. I even have a "whisker cleaner" ( a 45000 MFD capacitor sitting on a 80 volt transformer/full wave bridge, i.e. BIG DC supply) which I use to clear the internal whiskers that would short out the older Nicds when they were left un charged for long periods. (though it often spot welded the gator clips to the batteries :-)). I have read that the newer technology Nicds no longer have this issue. Too bad, this thing is impressive to watch in action....

Anyway,
I have a 10 year old Dewalt 14.4V drill with the XR battery type (dont have the model number handy) but the Dewalt guy tells me "this is the one model that the new universal Dewalt replacements dont fit". Naturally.
At this point since I was facing $100-120 for 2 replacements I figured it was close enough to the price of a new drill. But to quote imagineer "For me, being a cheap S.O.B. who likes fixing things, it wasnt so bad". Likewise, for me it's the principal of the thing. I KNOW it is filled with a number of Sub-C Nicd cells that can be had for as little as $2 each But.... I can't get the darned thing(s)open! Xsleeper mentioned he had opened a 14.4 volt pack but didnt describe how. Mine appear to be potted/epoxied shut. They have one screw in the middle but removing it loosens nothing. I have been waiting for them to die completely (1 has about 70% power for 10 minutes, the other about 80% power for 20 minutes) before I get out the Dremel and cut 1 of them open.

But after reading these posts I am hoping that someone knows the "trick" I am not seeing to get them to pop open. Any ideas?

TIA
 

Last edited by GregH; 01-11-06 at 04:06 PM. Reason: Remove link
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Old 01-11-06, 03:53 PM
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do I smell Spam ?
 
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Old 01-11-06, 04:26 PM
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Snarksdad,

my 14.4V XR battery DW9091 has 5 screws. One is deep inside a hole, the other 4 are around the "shaft" of the battery in plain sight. Yours must be pretty old to be designed differently, because my battery was ancient!

When my battery is sitting flat on it's bottom, there are 7 "pinky fingertip" sized indentations placed symetrically around the bottom inch of the battery. If you point the battery away from you so that the longest part is pointing away from you, the 4 screws are located right inline with those first 4 "indentations". Maybe your battery has some sort of one way "snap" fasteners in those locations? At any rate, I was going to say that if you were going to try cutting it apart, try making a small hole to pry at those 4 locations. I would think the design would be similar.
 
  #21  
Old 01-12-06, 09:36 AM
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Thanks for the reply Xsleeper. I took a look at the model number of the battery last night and it is a DW9091 but the only visible screw is the one "deep in the hole" as you say. I peeled the label off expecting the rest of the screws to be hidden there (a common manufacturers deterrent) but there were none. Looking at the seam where the edges of the lower case connects with the flat piece which has the charger connector is a very tight, apparently glued seam. I cannot even get a razor blade in the crack. So it does seem somewhere along the line Dewalt had a change of heart in allowing access to the battery cells. I wonder whether mine is newer or older than yours....I distinctly remember buying it in 1996 to build a gazebo and being impressed when I dropped it from a 10 foot ladder, watch it bounce off a concrete footer and then resume operation without a hitch. A fellow worker sporting a Makita drill picked it up and said "this is a superior tool". Since then I have had a bias toward Dewalt and have 6 or 7 Dewalt products in my shop collection. If I get a chance I will have a go at it this weekend. I may try a heat gun at the seam just to see what "moves" at the edges.

The 14.4 is no longer a critical need since at Christmas I found a Dewalt 18V 4 pack under the tree. Lowes (am I allowed to mention store names?) had these on sale for $220. The circ saw, recip saw, compact 1/2" drill, flashlight 2 batts and charger. I hope some of you got in on that deal!

Also I noticed that the web link I had included in my original post was deleted by a moderator. I assure you all it was not meant as an advertisement (though it did point at one). It came up in the Google search for "repair Dewalt battery" (as did this forum) and was an ad for a website that sends instructions for "resurrecting Nicad batteries" etc for $12.95. I figured folks here might have come across it before and had some insight into what process they might be selling.

Apologies for the Fau Pa.

I suppose somewhere in the FAQ I only skimmed there will be criteria as to what/when links are allowed in a post....I will read it more thoroughly

Snarksdad
 
  #22  
Old 01-20-06, 09:51 AM
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Talking Pack rebuilding.

Your 14.4 contains 12 sub-c power cells. These cells are 1.2 volts each. An 18 volt battery contains 15 cells. For all other batteries just divide the voltage by 1.2 and that is the number of cells that you need. I'm not familiar with the DW9091, I have DW9094 14.4 volt batteries. The case on these comes apart readily when you remove 5 screws. I also run Black and Decker batteries Q103 and PS140 which are also 14.4 volt. Just cut off the centering tab on the neck of the battery and the will all interchange into any tool that accepts that battery design. They are all the same inside and out once you remove that tab. I run a mix of tools from either brand and interchange them all. The XRP batteries are basically the same but use higher mAh rated cells. You can get the same results by rebuilding your pack with the same upgraded cells for a fraction of the cost. I'm still working on a corded adaptor
for use with the recip and circular saw. These high drain tools really eat up batt power and I would like the option to go corded without packing around a bunch of extra tools. If you need anymore info feel free to send me a note. Good luck
 
  #23  
Old 02-07-06, 11:11 AM
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DeWalt 14.4 xr Packs

Anyone know where I can some DeWalt 14.4 xr spent packs or empty cases. I need the newer type that screw together. Iím making some packs, canít bring myself to pay that high cost for factory DeWalt, plus I can up the Milli-amps. BTW, the only way I found to open the older style (single screw) 14.4 xr packs is with a Dremmel and cut them, not pretty!.

Bud
 

Last edited by htcamp; 02-07-06 at 11:52 AM.
  #24  
Old 02-08-06, 06:35 PM
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18V Milwaukee Batteries Gone Bad

I am not sure I can rebuild these batteries following the procedures outlined in this thread, and buying new batteries is too expensive; however, I found the name of a company called Voltman that will rebuild these for $35 each. Has anyone ever gone this route? Thanks. West Cobb
 
  #25  
Old 03-27-06, 02:57 PM
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Originally Posted by imagineer
It will take some doing, but you can repair cordless drill batteries. An 18 volt battery pack is made up with 12 "C" sized rechargable cells. These are available at Radioshack or any place that sells rechargable batteries.
hi imagineer:

Not sure if radio shack is cutting back on their supplies but they suck!! Tried to buy these rechargebable cells you're talking about (i actually need 6 as well) there but the only ones they had were about $8 for a 2 pack and those seemed to be the ones that were lined in plastic etc (looked like a regular household battery).. So I need 6 batteries and I'm not about to pay $24 for them when I get a new battery unit for about $30...

I'm going to try other places, but radio shack really is a waste of time...
 

Last edited by wannahack; 03-27-06 at 03:08 PM.
  #26  
Old 09-22-06, 09:23 AM
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Thumbs up New to this forum!!!

I am a new person to this forum but I have already repaired quite a few of these deWalt batteries, mainly 18v, I have went thru the "ressurection process" and replaced and rebuilt the packs entirely.
 

Last edited by DIYaddict; 09-22-06 at 09:38 AM. Reason: Removed offer/This is not allowed in forums
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Old 09-23-06, 02:38 AM
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I just happened to stumble across this post, and would like to put in my 2 cents worth. I fly radio contol airplanes which use NiCad batteries. Our planes are worth from $300 to several thousand dollars. Keeping them in one piece means having dependable batteries. Most rechargeable batteries from Radio Shack are junk, in my opinion. While they are advertised as have large capacity, they seldom will hold up to a high discharge rate, which is needed for power tools. The same goes for the rechargeables found at Wally World and other stores. For the best batteries, try Sanyo. They can stand high discharge rates and will also stand up to rapid charging (one hour charge). Cheaper batteries won't last long with rapid charging since they are usually designed for a overnight charge.

I won't get into things such as determining proper charge rates, balanceing cells, Delta-peak detection for end of charge, or the cycling of packs, since the tool chargers are not adjustable. I will say that I use a programmable charger for my Dewalt packs and get about 30% more capacity out of the pack, than with the Dewalt charger. How do I know the capacity? My charger has a digital readout that tells the capacity when I do a discharge/charge cycle to recondition the pack. Probably more than you wanted to hear. Just trying to help.

Nashcat
 
  #28  
Old 09-27-06, 01:50 PM
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I like to get deals, but I like my time

Gang,

Went to Interstate Battery Center and they sold me a higher Mah battery than I had for $59 instead of $79, I just asked for a discount.

Home Depot had the lower amp battery for $89 per.

They will rebuild them for $49.

I like that place.

Just my .02,

Eldorado
 
  #29  
Old 10-08-06, 08:39 PM
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Originally Posted by htcamp
Anyone know where I can some DeWalt 14.4 xr spent packs or empty cases. I need the newer type that screw together. Iím making some packs, canít bring myself to pay that high cost for factory DeWalt, plus I can up the Milli-amps. BTW, the only way I found to open the older style (single screw) 14.4 xr packs is with a Dremmel and cut them, not pretty!.

Bud
On the older style cases, remove the screw, use a box cutter with a fresh blade to score the lines where the top has been glued to the bottom. Use several passes to loosen the joints up. Then use a small flat screw driver to start the seperation prying a little at a time till they pop apart. Just did two packs this way. Also My charger does not like the new batteries anyone have advice on another charger to use or possible repairs for existing charger, it flashes light saying bad pack. Probing the packs a get 14.21 volts and 14.42 volts.
 
  #30  
Old 11-07-06, 06:42 PM
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I was wondering something about this. Going by the instructions that imagineer wrote. I found out that I have 2 completely dead cells. The battery pack itself says 18V XR+ NiCd. But everything I see online say they are NiMh, so which is it? I found batteries here.... http://www.onlybatteries.com/cat_featured_items.asp?cat1=13&cat=2&id=124&uid=1049 which leads me to another important question, which one is the one I get, or can you mix/match the ones you have. I doubt you can, which is why I'm asking. Thanks.
 
  #31  
Old 11-24-06, 09:56 PM
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I have a 12volt Dewalt that neither battery will hold a charge. When I charge them they will work fine for a short period of time, maybe 10-15 minutes then will quickly die out. When new the batteries lasted much longer under use.
I took the battery apart and tested each cell as described above. All tested fine. What is my next step?
Any Help would be appreciated.
Mark
 
  #32  
Old 11-19-07, 10:18 AM
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New guy, question

Guys, I'm reading this thread with interest but I have a question. If the old 18w packs are 1500mAh, how do I figure out the capacity PER battery?

They have up to 5000mAh batteries today (C size) so it should be possible to boost it up like crazy.
http://www.all-battery.com/index.asp...S&Category=355

The DC9096 are listed at 2000mAh and the people that rebuild them offer up to 3300mAh.

Also, someone said that the 18v pack takes 12 batteries. Should it not be 15?

Thanks

George
 
  #33  
Old 11-29-07, 04:47 AM
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I have a 12 volt Porter Cable drill that needs batteries. I may try to build a battery pack for it when they finally go.
I use a Ryobi 18 volt for most of my stuff. Its not a commercial job like the others but the batteries are only 40 bucks for 2.
They dont have the duration of more expensive drills but the life of the batteries are the same if not better then the heavy duty drills if used by a homeowner.
Nicad batteries need to be cycled and recharged and most home owners fail to keep them that way. The Ryobi batteries are strong enough to do most jobs with single battery but will need to be recharged when finished. Thats a good thing as that means they will be recharged after most uses and not put away in a half state of charge.
 
  #34  
Old 11-29-07, 06:34 AM
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you can now use the new Ryobi 18v battries with your old tools ,they are interchangeable

I haven't tried them yet but I did pick up the 12v lithium drill kit to use as a screw gun and I really like it . compact , powerful and battery life seems very good (only had it a week so im still in "testing " stage )

I was going to pick up a bosh screw gun but I like this better
 
  #35  
Old 12-03-07, 08:15 AM
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$35 from Voltman, for a new pack of batteries..I have had these in light duty use for the past year and am happy(no easy feat)..That DeWalt asks for over $50 for about the same thing shows the insensitivity of American manufacturers.
Sanyo(Japanese ) makes the best rechargeable
batteries ..
Figures - The Orientals seem to make the best of everything.
But why ??

But, now, the new technology is lithium-ion batteries, but I am not about to throw away the old drill and light that I have as long as they work..
 
  #36  
Old 07-18-08, 10:36 AM
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Zapping Dewalt 18v

Hi all, there's a video out on youtube somewhere that shows a guy "zapping" his rechargeable batteries using a welder. Yes, I said a welder.

Now being guy (brave + stupid + curious = man), I thought I'd give this a try, my first two attempts produced stellar results. I used a mig welder, identified the positive post (the front one if I recall correctly, and using some jumpers, hiding behind a wall, I zapped one my battery by dragging across the contact several times - do not leave attached to the contact or you will surely burn up contacts, the nicads or cause it to explode. One battery that prior registered zero on the multi-meter showed immediate results and finally took a charge.

The theory behind this technique is that the higher shot of juice can burn through the nicad "memory." I understand that this is neither safe, nor is it good for the long-term condition of the nicads, but to be honest, I got an additional 6mo. of use out one very dead battery.

Try at your own risk!
Peace.
 
  #37  
Old 10-13-08, 09:42 AM
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14.4v packs

Thanks again to all of those who contributed to this thread.

I have two aging 14.4x Dewalt packs, one of which reads 0V, the other of which reads about 8V when initially charged and drops to 6V after five minutes of useage. My plan for these is two-fold:

1) Empty the 0V pack and fill with 11 of these:
http://www.all-battery.com/sc3500mah...product=202828

I also plan to get their "smart" 12-16v charger (item number 01004) which does 0.7A and 1.4A charge rates with a bunch of other features which are way over my head. This should give me a super-pack which will last me a while.

2) I will take the used cells from the 0V pack and charge them one at a time in my AA NiMH/NiCd charger and see which ones come back to life. Any successfully resurrected cells will be spares to go into the 8V pack which I will drain down to 1V with a small lightbulb and then recharge with the new smart charger. I figure this should bring this pack back to roughly 90% of its original capacity.

Anyone see any flaws with this plan? (I already have both packs apart) and am I likely to have any problems charging the individual 0V sub-C cells in my old charger? It is a basic Energizer sub-shoebox size charger for AAA, AA, C, D & 9V batteries

Any experience and comments gratefully accepted

Thx
J
 

Last edited by jw2k_fr; 10-13-08 at 09:43 AM. Reason: Coherence of thought patterns :)
  #38  
Old 01-26-09, 04:07 PM
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I think that last suggestion is called fraud or theft by deception....
 
  #39  
Old 01-26-09, 06:19 PM
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I'm thinking recommending fraud is probably breaking the rules on this site.

Suggest the post be removed.
 
  #40  
Old 01-29-09, 11:22 PM
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Lith-ion

I see they have the lith-ion packs out now. You could do some serious damage with one of those bad boys. Anyone know if it's possible to convert am older style for a newer style?

The lith-ion packs fit all 18v xrp tools so i am assuming it can be done.
 
 

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