If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
Sears tools
"Ernest Christley" wrote I baby my batteries with the tenderest of loving care. I made two battery packs last 10 years, using it for nearly everything, and the batteries were still good enough to pass on to a brother-in-law. The new set was shot in six months. From Ron's experience, it may be that DeWalt has de-emphasized their 9V line. Could be; I know they want your to buy the 16 volt ones, and now, the 24 volt ones. It could be that they are pushing a 9 volt pack too hard during charging. The same charger is used for 9.6 to 18 volt, I know for a fact. Perhaps that is too many volts to feed into the 9.6 batteries. -- Jim in NC |
#12
|
|||
|
|||
Sears tools
"Ernest Christley" wrote Dang-it! I bet you're right. I noticed the batteries coming out of the new charger a lot warmer than the came out of the old one. I bet I would still have decent batteries if I had kept the old charger. Perhaps you could stick a voltage regulator chip into the charger, or experiment to find a resistor that would drop the voltage to a reasonable level. -- Jim in NC |
#13
|
|||
|
|||
Sears tools
"Morgans" wrote in message ... "Ernest Christley" wrote Dang-it! I bet you're right. I noticed the batteries coming out of the new charger a lot warmer than the came out of the old one. I bet I would still have decent batteries if I had kept the old charger. Perhaps you could stick a voltage regulator chip into the charger, or experiment to find a resistor that would drop the voltage to a reasonable level. -- Jim in NC The voltage regulator is the only correct solution, although I don't recall the proper shut-off voltage. Ideally, the charger should provide a fairly quick charging current and then shut off, or else drop to a couple of milliamps when the fully charged voltage is reached. IIRC, if the batteries are to last, the correct voltage varies with temperature and should be controlled within about 0.1 volt. I don't recall the correct voltage for a full charge, but 9.6 volts sounds like a stack of 8 nicad cells; so the figure of 11.6 volts sounds possible for some fairly normal temperatures. However, that is a distant and somewhat foggy memory--so it is only usefull as a starting point to search for the correct numbers. I hope this helps. Peter |
#14
|
|||
|
|||
Sears tools
Um...last time I checked, Nicad batteries were charged with a constant
current source, not a constant voltage soure. You can use a regulator IC with a properly connected resistor to make a constant current source. Scott Peter Dohm wrote: "Morgans" wrote in message ... "Ernest Christley" wrote Dang-it! I bet you're right. I noticed the batteries coming out of the new charger a lot warmer than the came out of the old one. I bet I would still have decent batteries if I had kept the old charger. Perhaps you could stick a voltage regulator chip into the charger, or experiment to find a resistor that would drop the voltage to a reasonable level. -- Jim in NC The voltage regulator is the only correct solution, although I don't recall the proper shut-off voltage. Ideally, the charger should provide a fairly quick charging current and then shut off, or else drop to a couple of milliamps when the fully charged voltage is reached. IIRC, if the batteries are to last, the correct voltage varies with temperature and should be controlled within about 0.1 volt. I don't recall the correct voltage for a full charge, but 9.6 volts sounds like a stack of 8 nicad cells; so the figure of 11.6 volts sounds possible for some fairly normal temperatures. However, that is a distant and somewhat foggy memory--so it is only usefull as a starting point to search for the correct numbers. I hope this helps. Peter -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
#15
|
|||
|
|||
Sears tools
Scott wrote:
Um...last time I checked, Nicad batteries were charged with a constant current source, not a constant voltage soure. You can use a regulator IC with a properly connected resistor to make a constant current source. Most of the current issue batteries (certianly the XRP Dewalts) are NOT NiCad. Mine are LiIon. Only the dumbest-ass slow nicad chargers were simple constant current chargers. The rapid chargers all used the pack temperature to regulate how much current they put in them. |
#16
|
|||
|
|||
Sears tools
Scott wrote:
Um...last time I checked, Nicad batteries were charged with a constant current source, not a constant voltage soure. You can use a regulator IC with a properly connected resistor to make a constant current source. Most of the current issue batteries (certianly the XRP Dewalts) are NOT NiCad. Mine are LiIon. Only the dumbest-ass slow nicad chargers were simple constant current chargers. The rapid chargers all used the pack temperature to regulate how much current they put in them. |
#17
|
|||
|
|||
Sears tools
After I wrote that, which is obviously the wrong sequence, I did a quick
search and found that a constant current plus voltage/temperature sensing was preferred. My recollection of the fully charged voltage was also much too high! Peter "Scott" wrote in message .. . Um...last time I checked, Nicad batteries were charged with a constant current source, not a constant voltage soure. You can use a regulator IC with a properly connected resistor to make a constant current source. Scott Peter Dohm wrote: "Morgans" wrote in message ... "Ernest Christley" wrote Dang-it! I bet you're right. I noticed the batteries coming out of the new charger a lot warmer than the came out of the old one. I bet I would still have decent batteries if I had kept the old charger. Perhaps you could stick a voltage regulator chip into the charger, or experiment to find a resistor that would drop the voltage to a reasonable level. -- Jim in NC The voltage regulator is the only correct solution, although I don't recall the proper shut-off voltage. Ideally, the charger should provide a fairly quick charging current and then shut off, or else drop to a couple of milliamps when the fully charged voltage is reached. IIRC, if the batteries are to last, the correct voltage varies with temperature and should be controlled within about 0.1 volt. I don't recall the correct voltage for a full charge, but 9.6 volts sounds like a stack of 8 nicad cells; so the figure of 11.6 volts sounds possible for some fairly normal temperatures. However, that is a distant and somewhat foggy memory--so it is only usefull as a starting point to search for the correct numbers. I hope this helps. Peter -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
#18
|
|||
|
|||
Sears tools
"Ron Natalie" wrote in message ... Scott wrote: Um...last time I checked, Nicad batteries were charged with a constant current source, not a constant voltage soure. You can use a regulator IC with a properly connected resistor to make a constant current source. Most of the current issue batteries (certianly the XRP Dewalts) are NOT NiCad. Mine are LiIon. Only the dumbest-ass slow nicad chargers were simple constant current chargers. The rapid chargers all used the pack temperature to regulate how much current they put in them. That's actually a couple of good points, and there should be some information on the battery packs stating what they are. A google search leads to a lot of information about each of the battery types, along with the obvious conclusion that there are a lot of questionable chargers out there for each of the types. By the way, my old AEG screwdriver (also sold as Milwaukee) uses a 2 cell NiCad battery pack--which explains why time alone will destroy the batteries even though the charger appears to be pretty good. Anyway, thanks for a good reminder to REALLY examine the tool, the battery and charger, and the litterature when buying tools in the future. Peter |
#19
|
|||
|
|||
Sears tools
"Ron Natalie" wrote Most of the current issue batteries (certianly the XRP Dewalts) are NOT NiCad. Mine are LiIon. Only the dumbest-ass slow nicad chargers were simple constant current chargers. The rapid chargers all used the pack temperature to regulate how much current they put in them. I think most of the newer non LiIon Dewalt batteries are nickel metal hydride. Only a couple years ago, they were still NiCads. Dewalt chargers for non LiIon batteries do not sense temperature. They have only a positive and negative lead, and there is nothing in the charger to sense temperature externally, as if that would do much good, anyway. They do use peak detecting charge technology, though. -- Jim in NC |
#20
|
|||
|
|||
Sears tools
On Sat, 17 Nov 2007 19:33:26 -0500, "Morgans"
wrote: "Ron Natalie" wrote That's a shame. Nearly all of my tools now are from the 18V Dewalt line to include: I've had no problem with the XRP batteries. One big difference in how long they last, is how you treat your batteries. One of the biggest battery killers is running them until they won't hardly turn the tool motor without any load on it. You should stop using the battery, and get a fresh one immediately after the RPM starts to drop noticeably. If you run your battery real hard, let it cool for at least 30 minutes, and an hour or two is better, before you charge it. After it is fully charged, it should be allowed to cool down a bit before you use it again. All this requires is enough batteries to do your job with some resting time between cycles. An extra couple batteries go a long way towards making all of them last much longer. Also, some of the Dewalt chargers come with a button on them, that you push to run them through several cycles of discharge and recharge, to condition them. I think that helps them out a bit, but it should not be over used. All batteries, and it does not matter which brand, have a limited number of cycles in them, before they start to go bad. Another thing I do, is to take the pack apart when it goes bad, and right after charging, read each individual cell's voltage. It will be very apparent that a few are totally zapped. If you have at least two bad packs, you can remove the bad cells from one, borrow cells from the other, and have a good battery pack, for a while, at least. There is a battery shop in my area that you can take the packs too and they will replace the cells for you. I believe it was $75 the last time I priced having the cells replaced for an 18V battery pack and that was for the higher Miliamp batteries. The owner said that he gets a lot of contractors in to have the cells replaced with the higher miliamp cells and they constantly brag about how much better they are than the new ones off the shelf. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Tools | ORVAL FAIRAIRN | Home Built | 24 | September 12th 05 08:03 PM |
Re.: Camloc Tools | Greg Piney | Home Built | 0 | May 4th 04 07:20 PM |
BRS and other tools | 2Poor2Fly4Real | Piloting | 1 | April 23rd 04 06:41 PM |
What tools do you take? | Michael Horowitz | Owning | 31 | March 8th 04 02:53 AM |
What tools do you take? | Michael Horowitz | Home Built | 14 | March 4th 04 02:07 PM |