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#1
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Charging a Ni-cad battery
I have a beard trimmer that runs on a Ni-cad battery that I recharge
about once a month when the battery runs low. Recently, the battery stopped being able to hold a charge. I charged it for ~12 hours, tested the voltage, and got zero. OK, fine, so I soldered in a new ni-cad, and everything works fine now. The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. Then I got to thinking about the charger, which is just a simple wall wart. The battery is one AA ni-cad, 1.2 V 600 mAh. The wall wart charger is labeled 2.3 V, and I measured 7.5 V DC actual output. The charger is what came with the trimmer, and molded into the trimmer is something about "use only charger # such-and-such", which is also the number on the charger. So I'm sure that the charger is the one that the manufacturer intented to be used with the trimmer. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? Should I find a new wall wart that has a voltage closer to 1.2 V? If so, what current output should it have? (I save each and every wall wart from every dead appliance that I have ever owned, so I have a wide selection to choose from a box in the attic, although I think most of them are 5V and up.) Ken |
#2
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Ken wrote:
I have a beard trimmer that runs on a Ni-cad battery that I recharge about once a month when the battery runs low. Recently, the battery stopped being able to hold a charge. I charged it for ~12 hours, tested the voltage, and got zero. OK, fine, so I soldered in a new ni-cad, and everything works fine now. The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. Then I got to thinking about the charger, which is just a simple wall wart. The battery is one AA ni-cad, 1.2 V 600 mAh. The wall wart charger is labeled 2.3 V, and I measured 7.5 V DC actual output. The charger is what came with the trimmer, and molded into the trimmer is something about "use only charger # such-and-such", which is also the number on the charger. So I'm sure that the charger is the one that the manufacturer intented to be used with the trimmer. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? Should I find a new wall wart that has a voltage closer to 1.2 V? If so, what current output should it have? (I save each and every wall wart from every dead appliance that I have ever owned, so I have a wide selection to choose from a box in the attic, although I think most of them are 5V and up.) Ken You found that voltages change depending on how you measure them. The battery is rated at the voltage it can deliver (likely under a specific load). The charger is rated at the voltage it delivers under a certain load. The voltage you measured was likely with a modern digital meter that have a very high resistance, resulting in the high voltage recorded. If you were to measure the voltage when you first put a battery in need of a charge on it and then measure it again when the battery is fully charged you are going to get two more measurements, the last likely near that 2.3V specified for the charger. Measure the voltage output of that 5V vampire with that same meter and no load and you might get something about 10V. The moral of the story, stick with the one designed for the use you have. -- Joseph Meehan Dia duit |
#3
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"Ken" wrote in message oups.com... I have a beard trimmer that runs on a Ni-cad battery that I recharge about once a month when the battery runs low. Recently, the battery stopped being able to hold a charge. I charged it for ~12 hours, tested the voltage, and got zero. OK, fine, so I soldered in a new ni-cad, and everything works fine now. The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. Then I got to thinking about the charger, which is just a simple wall wart. The battery is one AA ni-cad, 1.2 V 600 mAh. The wall wart charger is labeled 2.3 V, and I measured 7.5 V DC actual output. The charger is what came with the trimmer, and molded into the trimmer is something about "use only charger # such-and-such", which is also the number on the charger. So I'm sure that the charger is the one that the manufacturer intented to be used with the trimmer. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? Should I find a new wall wart that has a voltage closer to 1.2 V? If so, what current output should it have? (I save each and every wall wart from every dead appliance that I have ever owned, so I have a wide selection to choose from a box in the attic, although I think most of them are 5V and up.) Ken Stick with the recommended unit. The open circuit measurement doesn't mean much. 1.325 is the voltage of a fully charged cell. For a longer cell life don't leave it in the charger all the time. |
#4
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Under charge load it probably is the right charger and voltage of apx
1.36-1.5v. 1.35 is fully charged for a nicad. 1.2v is considered discharged. Likely just a cheap battery as alot of junk is made. Sanyo and Panasonic are tops. Just don`t leave in the charger and overcharge, and over discharging ruins nicads. When it just slows it is dead. 1.2v is discharged |
#5
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I've got a Norelco that's doing a similar thing. I carry it in the truck for
when I forget to shave at home. It's only got one cell. I'm really tempted to drill a hole in the side of the shaver, and wire on a single AA battery holder. Put a high capacity NiMH cell in. Then in two years just pop in another cell. Or use an alkaline (I've got lots of those) and change battery when it gets weak. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "Ken" wrote in message oups.com... I have a beard trimmer that runs on a Ni-cad battery that I recharge about once a month when the battery runs low. Recently, the battery stopped being able to hold a charge. I charged it for ~12 hours, tested the voltage, and got zero. OK, fine, so I soldered in a new ni-cad, and everything works fine now. The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. Then I got to thinking about the charger, which is just a simple wall wart. The battery is one AA ni-cad, 1.2 V 600 mAh. The wall wart charger is labeled 2.3 V, and I measured 7.5 V DC actual output. The charger is what came with the trimmer, and molded into the trimmer is something about "use only charger # such-and-such", which is also the number on the charger. So I'm sure that the charger is the one that the manufacturer intented to be used with the trimmer. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? Should I find a new wall wart that has a voltage closer to 1.2 V? If so, what current output should it have? (I save each and every wall wart from every dead appliance that I have ever owned, so I have a wide selection to choose from a box in the attic, although I think most of them are 5V and up.) Ken |
#6
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"Stormin Mormon" wrote in message ... I've got a Norelco that's doing a similar thing. I carry it in the truck for when I forget to shave at home. It's only got one cell. I'm really tempted to drill a hole in the side of the shaver, and wire on a single AA battery holder. Put a high capacity NiMH cell in. Then in two years just pop in another cell. Or use an alkaline (I've got lots of those) and change battery when it gets weak. You might want to use at least a C cell. I wonder if it would happen if it was hooked to 12 volts. DC motors draw very little current unless they stall. The faster they run the more back EMF they create. Still, 12 might be too much for it. I did something along that line. I had an old rechargeable B&D screwdriver with two sub C cells. They died and the instructions were how to dispose of the whole thing. I opened it up and about three feet of heavy wire out. I found that the charger would charge 4 batteries if left on long enough so I hooked up 4 D cells. It has power now!! |
#7
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Get rid of the problematic Ni-cads
Go to Wal-Mart and buy the NiMh rechargeables. They are the same type of battery that digital cameras often use. The have no real memory effect and are cheaper than N-cads. You can usually find the batteries sold with a charging unit. I have found a four AA battery charger with four batteries for as low as $10 at Wal-mart. You can also browse http://www.thomasdistributing.com/ |
#8
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Ken wrote: I have a beard trimmer that runs on a Ni-cad battery that I recharge about once a month when the battery runs low. Recently, the battery stopped being able to hold a charge. I charged it for ~12 hours, tested the voltage, and got zero. OK, fine, so I soldered in a new ni-cad, and everything works fine now. The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. Then I got to thinking about the charger, which is just a simple wall wart. The battery is one AA ni-cad, 1.2 V 600 mAh. The wall wart charger is labeled 2.3 V, and I measured 7.5 V DC actual output. The charger is what came with the trimmer, and molded into the trimmer is something about "use only charger # such-and-such", which is also the number on the charger. So I'm sure that the charger is the one that the manufacturer intented to be used with the trimmer. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? Should I find a new wall wart that has a voltage closer to 1.2 V? If so, what current output should it have? (I save each and every wall wart from every dead appliance that I have ever owned, so I have a wide selection to choose from a box in the attic, although I think most of them are 5V and up.) Ken Lead acid battery chargers are voltage dependent (i.e. 13.5v to charge a 12v battery). Ni-Cad battery chargers are current dependent (i.e. ~ 500ma charging current). So the voltages you measured are somewhat irrevelant. You can take a 12v battery charger and hook a 12v lightbulb that draws 300-500ma in series with your Ni-Cad battery and it will charge just fine. I've done it for years. Bob S. |
#10
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Rich256 wrote:
1.325 is the voltage of a fully charged cell. A fully-charged cell that's in good condition, you mean. As they lose capacity through abuse, the terminal voltage goes up. -- I miss my .signature. |
#11
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"Ken" wrote in message oups.com... The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. From my experience in using ni-cads for the past 30 years or so, you did good. they do not last forever. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? No it is probably just fine. Some chargers give a high reading under no load. Others can expain it better than I can. Stick with what you have. |
#12
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"Joseph Meehan" wrote in
: wrote: Get rid of the problematic Ni-cads Go to Wal-Mart and buy the NiMh rechargeables. They are the same type of battery that digital cameras often use. The have no real memory effect and are cheaper than N-cads. You can usually find the batteries sold with a charging unit. I have found a four AA battery charger with four batteries for as low as $10 at Wal-mart. You can also browse http://www.thomasdistributing.com/ If I am guessing right, the OP needs a battery that is soldered in the device. He may not be able to find a NiMh with the proper solder strips attached. Really no need for NiMh as the Ni-cads do just fine. The NiCd battery in his device is probably not a standard AA size,either. It could be a 2/3A,N,or smaller NiCd.("A" cells are slightly larger in diameter than a AA cell.) -- Jim Yanik jyanik at kua.net |
#13
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clifto wrote in :
Rich256 wrote: 1.325 is the voltage of a fully charged cell. A fully-charged cell that's in good condition, you mean. As they lose capacity through abuse, the terminal voltage goes up. ISTR that it takes 1.55v per cell for charging a NiCd.(loaded V) You need more voltage than what the cell is rated for. -- Jim Yanik jyanik at kua.net |
#14
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"Edwin Pawlowski" wrote in
om: "Ken" wrote in message oups.com... The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. From my experience in using ni-cads for the past 30 years or so, you did good. they do not last forever. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? No it is probably just fine. Some chargers give a high reading under no load. Others can expain it better than I can. Stick with what you have. I have a Dustbuster that the first pack lasted for 10 years,the cells are designed to be charged 24/7/365,while most NiCds are not. The Dewalt repair center charged less to replace the pack than for what I could have bought new cells from Digi-Key(of the same charge type). -- Jim Yanik jyanik at kua.net |
#15
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"Joseph Meehan" wrote in message ... wrote: Get rid of the problematic Ni-cads Go to Wal-Mart and buy the NiMh rechargeables. They are the same type of battery that digital cameras often use. The have no real memory effect and are cheaper than N-cads. You can usually find the batteries sold with a charging unit. I have found a four AA battery charger with four batteries for as low as $10 at Wal-mart. You can also browse http://www.thomasdistributing.com/ If I am guessing right, the OP needs a battery that is soldered in the device. He may not be able to find a NiMh with the proper solder strips attached. Really no need for NiMh as the Ni-cads do just fine. -- Joseph Meehan Dia duit There are a couple pros to using ni-cd over NiMH if the info I read on the net was actually correct. Ni-Cd hold a charge for longer when not in use and I believe will endure more charge cycles then NiMH. Also, NiMH is rather nasty if it is heated to above a certain (rather high) temperature. I usually tape the trigger on when my Ni-Cd tools run low and let it completely drain the battery before I charge it. They hold a good charge for quite a while. I've found the tool wears out before the battery does... but I'm a little rough. |
#16
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On 2 Jun 2005 00:31:38 GMT, Jim Yanik . wrote:
"Edwin Pawlowski" wrote in . com: "Ken" wrote in message oups.com... The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. From my experience in using ni-cads for the past 30 years or so, you did good. they do not last forever. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? No it is probably just fine. Some chargers give a high reading under no load. Others can expain it better than I can. Stick with what you have. I have a Dustbuster that the first pack lasted for 10 years,the cells are designed to be charged 24/7/365,while most NiCds are not. The Dewalt repair center charged less to replace the pack than for what I could have bought new cells from Digi-Key(of the same charge type). It is generally accepted that you can charge sealed NiCads at 1/10th capacity on a continual basis. ( 500mA battery on a 50mA charger) DJ |
#17
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Olaf,
Good advice, but I don't agree with taping the trigger to fully discharge the cells. That is overkill and all of my electrical engineering buddies have advised me that 100% discharge to avoid memory effects is not the way to go. When you notice that your drill is struggling to operate, then recharge at that time. You'll get much better life from the cells. Gideon =============== Olaf wrote in message ... "Joseph Meehan" wrote in message ... wrote: Get rid of the problematic Ni-cads Go to Wal-Mart and buy the NiMh rechargeables. They are the same type of battery that digital cameras often use. The have no real memory effect and are cheaper than N-cads. You can usually find the batteries sold with a charging unit. I have found a four AA battery charger with four batteries for as low as $10 at Wal-mart. You can also browse http://www.thomasdistributing.com/ If I am guessing right, the OP needs a battery that is soldered in the device. He may not be able to find a NiMh with the proper solder strips attached. Really no need for NiMh as the Ni-cads do just fine. -- Joseph Meehan Dia duit There are a couple pros to using ni-cd over NiMH if the info I read on the net was actually correct. Ni-Cd hold a charge for longer when not in use and I believe will endure more charge cycles then NiMH. Also, NiMH is rather nasty if it is heated to above a certain (rather high) temperature. I usually tape the trigger on when my Ni-Cd tools run low and let it completely drain the battery before I charge it. They hold a good charge for quite a while. I've found the tool wears out before the battery does... but I'm a little rough. |
#18
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Andy writes
I disagree. It is generally accepted that the 1/10 rate is the desired rate to charge a NiCad without overheating. Once the cell is fully charged, you can THEN overcharge it if you leave it there..... So 1/10 for about 15 hours is a good rule of thumb to get to full charge...... If you want to "float" it, drop the charging current to 1 or 2 ma to just equal the self-discharge rate. Andy |
#19
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DJ wrote: It is generally accepted that you can charge sealed NiCads at 1/10th capacity on a continual basis. ( 500mA battery on a 50mA charger) ========== DJ, Yep - that is the 16 hour charge rate and it is the basis for many/most dumb chargers. Unfortunately, many of us are in a hurry and some manufacturers have put out equally dumb quick chargers which will begin toasting battery packs once they have reached full charge. Sadly, the general public doesn't realize why their cordless items need new battery packs every year or so. Gideon |
#20
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Andy writes:
Since the best way to charge a NiCad is with a constant charging current, it looks like the wall wart has been design to do that. It probably has a rectifier inside and a series resistor set to approximately: 7.5 - 1.2 ---------------- ohms or around 1200 ohms .05 in which case it is a very inefficient supply, but will provide a fairly constant charging current of, in this case, 50 ma. This is a cheap way to do it, but it is foolproof , works very well, and doesn't have a failure mode that results in a battery explosion.... You can verify this by reading the open circuit voltage (which you said was 7.5 volts, and shorting the output to ground and reading the short circuit current. That gives you the internal Thevinen resistance. If it is anywhere in the vicinity of 1K-2K, you know that is what they are doing...... I doubt that there are any electronics inside the wall wart other than a rectifier and a resistor, and probably not even a filter capacitor since it isn't needed...... If this is the case, Meehan is correct when he says you should not substitute another wall wart since it will not have the current limiting resistor. Andy |
#21
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Gideon wrote:
Olaf, Good advice, but I don't agree with taping the trigger to fully discharge the cells. That is overkill and all of my electrical engineering buddies have advised me that 100% discharge to avoid memory effects is not the way to go. When you notice that your drill is struggling to operate, then recharge at that time. You'll get much better life from the cells. Gideon =============== Olaf wrote in message ... "Joseph Meehan" wrote in message ... wrote: Get rid of the problematic Ni-cads Go to Wal-Mart and buy the NiMh rechargeables. They are the same type of battery that digital cameras often use. The have no real memory effect and are cheaper than N-cads. You can usually find the batteries sold with a charging unit. I have found a four AA battery charger with four batteries for as low as $10 at Wal-mart. You can also browse http://www.thomasdistributing.com/ If I am guessing right, the OP needs a battery that is soldered in the device. He may not be able to find a NiMh with the proper solder strips attached. Really no need for NiMh as the Ni-cads do just fine. -- Joseph Meehan Dia duit There are a couple pros to using ni-cd over NiMH if the info I read on the net was actually correct. Ni-Cd hold a charge for longer when not in use and I believe will endure more charge cycles then NiMH. Also, NiMH is rather nasty if it is heated to above a certain (rather high) temperature. I usually tape the trigger on when my Ni-Cd tools run low and let it completely drain the battery before I charge it. They hold a good charge for quite a while. I've found the tool wears out before the battery does... but I'm a little rough. Agreed. You can reverse bias the weaker cells in the pack that way and bugger them up real good.The "memory effect" with nicads is a much overated problem. About the only times it really comes into play and reduces the capacity of the battery is with devices like cordless phones, when they are used in a mode where they get put back on the charger after each short phone call and never really get discharged very much at all. Jeff Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "Truth exists; only falsehood has to be invented." |
#22
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Actually, it really is a standard AA size. I expected to see a sub-C
or something when I opened it up. I had some good AA NiCd batteries laying about, so I soldered one in. It didn't have the solder tabs, but I was able to get a blob of solder to stick to each end without cooking the battery with heat. Ken |
#23
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Ken,
Without getting into the chemistry of ni-cads, keep in mind these facts: (New) ni-cads are typically good for about 1000 charge / discharge cycles. Shelf life depletes the charge about 1% a day. Occasional deep discharge does help you get your 1000 cycles. Batteries may be kept on the charger continuously in some cases. Let me explain. Assume your "AA" battery has a listed current rating of 1100 milliamp hours (Mah). This means it should deliver 1100 milliamps for 1 hour or 110 milliamps for 10 hours or 11 milliamps for 100 hours. You get the idea. The 1 hour rate (1100) is known as it's "1R" parameter. Now, regarding chargers, you can charge a totally dead cell at the 1R rate (1100 milliamps) and expect a complete charge in just over 1 hour. You can also charge at the 1/10R rate for about 14 hours and get the same results. The important factor to remember is that once a cell is completely charged, a high charge rate will cause it's temperature to rise and that's a "bad thing". The trick is to know when a cell is "full" so the charger current can be reduced or stopped. Two ways exist to determine a full charge. Carefully monitor the cell voltage or carefully monitor the internal temperature (rectal and oral have no meaning here). In specialized cells (think Motorola commercial walkie-talkies) where quick charging is desirable, custom batteries are built with internal temperature sensors. That's why these batteries have more than two contacts. Customized (smart) chargers use these sensors to know when to reduce the high charge rate (1R) to the 1/10R rate. Finally, a ni-cad cell can be left connected to a 1/10R charger indefinitely with no ill effects. The off-gassing that occurs is offset by the re-combining chemistry within the cell so overheating does not occur at the 1/10R rate. How do you know if your wall wart is designed to deliver at the 1/10R rate? Easy. If the owners manual indicates a complete charge may take 14 - 16 hours, you have one. If it says it can charge a dead battery in substantially less time, you don't. Nickel metal hydride (Nimh) and lithium ion cells have different rules. Another time, perhaps. "Ken" wrote in message oups.com... I have a beard trimmer that runs on a Ni-cad battery that I recharge about once a month when the battery runs low. Recently, the battery stopped being able to hold a charge. I charged it for ~12 hours, tested the voltage, and got zero. OK, fine, so I soldered in a new ni-cad, and everything works fine now. The trimmer is only a few years old, so I thought the battery died earlier than I would have expected. Then I got to thinking about the charger, which is just a simple wall wart. The battery is one AA ni-cad, 1.2 V 600 mAh. The wall wart charger is labeled 2.3 V, and I measured 7.5 V DC actual output. The charger is what came with the trimmer, and molded into the trimmer is something about "use only charger # such-and-such", which is also the number on the charger. So I'm sure that the charger is the one that the manufacturer intented to be used with the trimmer. Did the higher than expected voltage on the charger lead to the early demise of the ni-cad battery? Should I find a new wall wart that has a voltage closer to 1.2 V? If so, what current output should it have? (I save each and every wall wart from every dead appliance that I have ever owned, so I have a wide selection to choose from a box in the attic, although I think most of them are 5V and up.) Ken |
#24
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"Craven Morehead" wrote in
: Finally, a ni-cad cell can be left connected to a 1/10R charger indefinitely with no ill effects. I do not believe this to be true. Digi-Key lists NiCds *specifically designed* to be left on the charger when not in use. If what you said was true,this would not be necessary. My own experience also shows it to be false. -- Jim Yanik jyanik at kua.net |
#25
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Ken wrote:
Actually, it really is a standard AA size. I expected to see a sub-C or something when I opened it up. I had some good AA NiCd batteries laying about, so I soldered one in. It didn't have the solder tabs, but I was able to get a blob of solder to stick to each end without cooking the battery with heat. Ken Same with mine, but I bought a new NiCd and for 25¢ they spot welded the tabs. -- Joseph Meehan Dia duit |
#26
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I've read this isn't a good idea. Sometimes one cell goes weak before the
others, and then you get voltage reversal on the weak cell. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "Olaf" wrote in message ... I usually tape the trigger on when my Ni-Cd tools run low and let it completely drain the battery before I charge it. They hold a good charge for quite a while. I've found the tool wears out before the battery does... but I'm a little rough. |
#27
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Agree. I don't believe in total discharge. I was involved with recharging
banks of NiCad batteries. We never deeply discharged and had them last for 20 years or more. Of course those were big commercial units. We never let them get below 50% state of charge. My theory is that memory only shows up if you repeatedly discharge to the same level of state of charge. Varying the depth of discharge or even just one deep one with wipe out any accumulated memory effect. I think more important is the number of discharges. For tools and the like I keep them on a curcuit where I turn on a switch occasionaly for a few minutes. A timer would work too. "Stormin Mormon" wrote in message ... I've read this isn't a good idea. Sometimes one cell goes weak before the others, and then you get voltage reversal on the weak cell. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "Olaf" wrote in message ... I usually tape the trigger on when my Ni-Cd tools run low and let it completely drain the battery before I charge it. They hold a good charge for quite a while. I've found the tool wears out before the battery does... but I'm a little rough. |
#28
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Rich256 wrote:
Agree. I don't believe in total discharge. I was involved with recharging banks of NiCad batteries. We never deeply discharged and had them last for 20 years or more. Of course those were big commercial units. We never let them get below 50% state of charge. My theory is that memory only shows up if you repeatedly discharge to the same level of state of charge. Varying the depth of discharge or even just one deep one with wipe out any accumulated memory effect. There may be something to that. I will add one additional personal observation. It appears that the earlier (like 1970) NiCds did suffer from the memory effect much more than today's do. It may be due to different chargers, but I suspect they made some improvement to battery formula and design over the years. Those old NiCd batteries in the flashes for the Polaroid 100 cameras all seemed to have the problem. I recovered many of them for irate customers back then. Two or three deep cycles did the trick. That and instructions to allow them to discharge fully from time to time, seemed to make happy customers out of un-happy ones. I think more important is the number of discharges. For tools and the like I keep them on a curcuit where I turn on a switch occasionaly for a few minutes. A timer would work too. "Stormin Mormon" wrote in message ... I've read this isn't a good idea. Sometimes one cell goes weak before the others, and then you get voltage reversal on the weak cell. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "Olaf" wrote in message ... I usually tape the trigger on when my Ni-Cd tools run low and let it completely drain the battery before I charge it. They hold a good charge for quite a while. I've found the tool wears out before the battery does... but I'm a little rough. -- Joseph Meehan Dia duit |
#29
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Jim Yanik wrote:
clifto wrote in : Rich256 wrote: 1.325 is the voltage of a fully charged cell. A fully-charged cell that's in good condition, you mean. As they lose capacity through abuse, the terminal voltage goes up. ISTR that it takes 1.55v per cell for charging a NiCd.(loaded V) You need more voltage than what the cell is rated for. With the charger attached to the battery, 1.55V isn't a bad estimate for the voltage you'll see at full charge. With the charger detached, 1.325V is a decent estimate for the battery voltage. -- I miss my .signature. |
#30
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Thanks for all the info. I don't recall the exact number, but I do
recall the manual saying something about the charge taking the better portion of a day. Basically, I try to trim my beard some morning, find that it is dead, plug in the charger, and then unplug it either that night or else the next morning if I forget. Ken |
#31
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"Jim Yanik" . wrote in message .. . "Craven Morehead" wrote in : Finally, a ni-cad cell can be left connected to a 1/10R charger indefinitely with no ill effects. I do not believe this to be true. Digi-Key lists NiCds *specifically designed* to be left on the charger when not in use. If what you said was true,this would not be necessary. My own experience also shows it to be false. Jim Yanik jyanik at kua.net Digi-Key does not make the batteries; they only sell them. This claim of unique capability is only sales talk. They claim a special benefit which is, in fact, common to all ordinary NiCads -- a widespread practice with sales people. SJF |
#32
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"Gideon" wrote in message ... Olaf, Good advice, but I don't agree with taping the trigger to fully discharge the cells. That is overkill and all of my electrical engineering buddies have advised me that 100% discharge to avoid memory effects is not the way to go. When you notice that your drill is struggling to operate, then recharge at that time. You'll get much better life from the cells. Gideon Cool! Thanks. :-) |
#33
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Ken wrote in message ps.com... Actually, it really is a standard AA size. I expected to see a sub-C or something when I opened it up. I had some good AA NiCd batteries laying about, so I soldered one in. It didn't have the solder tabs, but I was able to get a blob of solder to stick to each end without cooking the battery with heat. Ken Being a cheap basthud I'd check the battery by subjecting it to a quick shot at a higher voltage then check to see if the cell is still dead. I've zapped apperently dead cells back to stretch the life a bit. I hit a cell with the 12v battery charger (i said quick- a touch ) then I checked to see if the battery is still dead. Leave it sit for perhaps 6 hrs and see if it is still holding a charge. About 1/3 of the time , I can manage to get the dead cell to hold the charge for a while, then I go to a complete slow charge (a typical 500-740 aa cell) will be charged at 50mah overnight.If you already have the cel why not give it a shot. I just retired a 500mah aa nicad that had a 1974 manufacter date. Course it was down to mebbe 40% of capacity for the last year, but I did get some work outa the battery. Pat |
#34
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"SJF" wrote in news:d0Ine.56$xr.35@fed1read05:
"Jim Yanik" . wrote in message .. . "Craven Morehead" wrote in : Finally, a ni-cad cell can be left connected to a 1/10R charger indefinitely with no ill effects. I do not believe this to be true. Digi-Key lists NiCds *specifically designed* to be left on the charger when not in use. If what you said was true,this would not be necessary. My own experience also shows it to be false. Jim Yanik jyanik at kua.net Digi-Key does not make the batteries; they only sell them. This claim of unique capability is only sales talk. They claim a special benefit which is, in fact, common to all ordinary NiCads -- a widespread practice with sales people. SJF Bulls..t. It's not "sales talk",it's in their printed catalog. -- Jim Yanik jyanik at kua.net |
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