Replies

1. 
   Jeff_Clarke_ | Oct 03, 2000 04:01am | #1

   *
   Maybe it has something to do with this problem.

   Jeff

1. 
   Ryan_C | Oct 03, 2000 01:19pm | #2

   *14 months and 22 months out of a battery sounds pretty good to me.

1. 
   Phill_Giles | Oct 03, 2000 03:53pm | #3

   *Good point. Reading the fine print, 200 to 300 charges is about the life of better Ni-Cads. And that goes down if you abuse the batteries with constant topping up rather than taking them down to 5% each time. Theoretically, if you're not using the full torque of the machine, your batteries could have slipped down to 1/2 their original delivery capability and you might not notice. Anecdotally, I've heard the Panasonics (remember, you don't know who's batteries are inside unless you take the pack apart) last substantially longer while the Vartas deliver the most power.

1. 
   CaseyR_ | Oct 03, 2000 07:51pm | #4

   *I remember reading that the higher the voltage of the battery pack, the shorter its expected life. I don't remember the specifics, but the life expectancy given for 18v units was considerably shorter than 12v ones.

1. 
   Ryan_C | Oct 04, 2000 12:16am | #5

   *There was an article in JLC about this. higher voltage means bigger packs. That means more power being used with less surface area for heat to escape. (as they get bigger, the volume of the battery back increases faster than the surface area does)So the pack heats up and does damage to itself.

2. 
   ArcWood_ | Oct 04, 2000 12:27pm | #6

   *Yeah there was a similar article about it in Fine Woodworking a while back. Seems like they could getthe fan of the motor to blow down through the battery.

3. 
   herb_kelley | Oct 04, 2000 05:34pm | #7

   *Shorter life for 18V vs 12V makes sense given that the 18V contains 50% more batteries. Since the failure of one battery in the chain will cause failure of the pack, more batteries means shorter unit life with all else being equal. By the way, I remember a thread by someone who repaired his battery packs by replacing only the bad battery/batteries with Radio Shack? product. As I remember the discussion there was at least one comment questioning if this was a cost effective DYI tool repair. Guess it depends on how you valueyour "free" time.

4. 
   Joel_K. | Oct 06, 2000 02:05am | #8

   *I've had a DeWalt 14.4 hammerdrill for 'bout four years now...batteries are original and maybe, maybe starting to fade. Full-time tool; lotta stainless, lotta tapcons, lotta deck screws, lotta holes sawed. I keep all my tools out of the sun, I'll give a tool a break if I've been whipping on it for a few minutes; heat is what kills batteries, and certainly does the motors/bearings of your stuff no good either.Joel K.

5. 
   Mad_Dog | Oct 08, 2000 05:37am | #9

   *Do you frequently use the tools? I have used my DW drill and saw every week for almost 3 years, no loss of power or duty. Always running them down, and charging. Seems to be good for them.MD

6. 
   gstringe_ | Oct 09, 2000 03:31am | #10

   *Sometimes you can electrically repair a nicad by some short high voltage spikes in the charge mode. Or sometimes some short high current charges of a few seconds apiece. But for those who are not electrically adept it is best not to mess with it. I do it all the time as I have a lot of nicads in my care but remember that batteries can explode. You have to be prepared in these experiments to be able to chuck the battery in a non flamable container as it is possible for the battery to internally short and cause serious overheating.I suspect that many battery failures are caused by crummy chargers.A nicad cell has a voltage of about 1.25 volts so you can see that these paks are made up of many cells in series and only one high impedence cell can cause the whole pak to not be able to deliver current.Radio Shack is a possible source if the physical size is right and amp rating is compatable.I actually have an old Skill 9.6 volt that I replaced the nicad with a lead acid 12 volt. Runs faster/ longer/ more power but I had to saw the case apart and glue/tape/adapt etc. I figure I got at least twice the cost of a replacement in money and trouble, but what fun!!!

7. 
   Phill_Giles | Oct 09, 2000 06:31am | #11

   *Although RadioShack does now carry a line of really heavy-duty NiCads, I would suggest that you instead look for a source of Varta, Panasonic Industrial, or some other reasonable equivalent generic cell as a replacement. I've been sourcing these from Electrosonic and Future Active Components in the NE Toronto area, there must be lots of electronics suppliers where-ever you live. PS - electronic suppliers (i.e. the ones who supply industry) are a terrific source of adhesives and epoxies; and, unlike a box store, they generally are thrilled to custom order anything in their suppliers' catalogs.

8. 
   Andy_Engel_ | Oct 09, 2000 06:45pm | #12

   *You might want to look in FHB #128, January 2000, pp 108-109 for an article by Gary Katz that explains the care and feeding of NiCads. The most important item in that article, I think, is the explanation of why you should NOT run down your batteries completely. That's a sure way to kill them. Gary gathered the information in that article by pestering the engineers at most of the big tool makers, as well as at Panasonic. Also, there's a great photo of FHB's coffee pot.Andy

9. 
   Luka_ | Oct 10, 2000 01:45am | #13

   *I missed that issue and would like to have a gander at the article.Here's hoping someone has a scanner and knows how to make an attatchment to e-mail...b : )

10. 
    gstringe_ | Oct 10, 2000 03:58am | #14

    *Absolutely-letting a nicad go dead is sure demise of the battery.

11. 
    Ryan_C | Oct 10, 2000 05:21pm | #15

    *Give us some more info on "repairing" NiCad's with high current. What voltage? For how long? Why does it work?

12. 
    Phill_Giles | Oct 10, 2000 06:11pm | #16

    *Freezing and arcing with a high-voltage source (like an automotive coil) were old folk rememdies for blanking the "memory" of early Ni-Cad cells. As mentioned, it is not without risk. I having asked the Ni-Cad manufacturers about the practise; they've replied that this won't restore a worn-out cell, but they hedge on the "memory" aspect.

13. 
    R.B.W. | Oct 11, 2000 06:38am | #17

    *I appreciate all of the feed back, as I thought I might be doing something wrong. I can see there are 2 schools of thought on running batteries completely dead. The DEWALT service centre in Ottawa, told me that at every tenth charge, the battery should be run down completely. I have since had the battery replaced at the store it was purchased from, just like the other battery in May. They have been very good about replacing them, but I still feel a battery should last for longer than 22 months.

14. 
    Will_Phillips | Oct 13, 2000 12:35am | #18

    *R.B.W.I had a similar problem with the same item. A voltmeter showed about a volt so I took the battery apart and found that one of the contacts to one of the cells (soldered) had come apart. I soldered the cell, assembled the battery and it's been fine since (mos.) Even though it was under warranty sometimes it's easier just to fix it yourself.

15. 
    george_stringe | Oct 13, 2000 05:45am | #19

    *repairing nicads-The high voltage is use is 2 or 3 times the voltage of the pa. When applying high voltage to nicads it is just a number of quick sparks of the clip lead to the battery terminal. Maybe 6, maybe a dozen times. I can't put my finger on the exact technical description of the battery condition, but what happens is that small little tendrils(?) grow on one of the battery elements that can short to the adjacent element of the cell. These high voltage spikes burns these tendrils off.The high current method is to use short applications of high current that is 3 to 5 times the normal fast charge rate for short durations of around three seconds each. You do have to be careful here because you will not be able to feel the heat build up in the battery very easily because of the insulation qualities of the battery case. If the battery feels very warm after this, you have applied plenty of current to the battery. It might take a couple of applications of this to help or it might not help at all but a ruined battery is worse than one that sort of works so be careful.In a multicelled pak it would be best to try and rejuvenate the bad cells but that is not always practical, so applying the high current, high voltage method to the good cells as well as the bad ones could be shortening the life of the good ones.Every multicelled pak I have ever taken apart has one or at most two bad cells.If the pak is destined for the recycle bin, it is worth a try.You really need a varible power supply to do this with volt and amp meters so you can see what you are doing.good luck

2. 
   R.B.W. | Oct 13, 2000 05:45am | #20

   *
   I own 3 18 volt DEWALT batteries, that I use in the trim saw and drill/driver. I have already replaced 1 battery at about 14 months and now at 22 months I have to replace battery #2. The second won't last in the saw for 10 seconds, after being in the charger for 24 hours. The DEWALT service centre informed me that they have had no problems with their 18 volt batteries, although they are know recommending to drain the batteries completely before charging, even though the battery has no memory. The tools are not being used for major production work. If anyone has similar experiences or tips, please let me know. I have a dozen other DEWALT products and I am very satisfied with their products, except for this battery problem.