I sometimes leave a device unused for years. Other times I leave it plugged in. Is there a poor man's guide to fixing batteries with "memory" (or whatever) problems?
- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
Basically put them through some discharge/charge cycles.
Alot of times nothing works, NiCds have a finite life.
What chemistry? Cycling a BATTERY may do more harm than good if any of the cells are shorted, common with disused NiCd's Cycling the CELLS individually has a higher probability of success.
harge/charge cycles. > > Alot of times nothing works, NiCds have a finite l ife. > What chemistry? Cycling a BATTERY may do more harm than good if any of the cells are shorted, common with disused NiCd's Cycling the CELLS indi vidually has a higher probability of success.
If any of the cells are shorted that "harm" doesn't matter much does it ? I think one of the problems is when the cells become unbalanced. In that cas e I agree that cycling them individually is much better, but in alot of cas es that is impossible or at least impractical.
As far as battery technology has come lately, their limitations are still t he main reason we do not have electric cars. Adequate batteries are not che ap for cars. The motors are great, outperforminh gas by quite a margin, par tly because they don't need a transmission.
NiCds would be a total waste in cars for example. Capacity versus size make s them unsuitable even for modern cellphones. NiCds simply are outdated, an d of a technology that should advance for a bunch of reasons. Some advances in technology are not desirable, I can think of quite a few, but batteries need to improve. Even the latest and greatest have a finite life.
They are also all environmental nightmares. Even if they don't improve capa city much, if they could get them to last longer it would be a definite ste p in the right direction.
Too bad there are so many problems eith retrofitting newer batteries into o lder equipment that used to use NiCds. One of the problems of course is ind ustry's refusal to do it because it would not help their profits.
** Back in 1996, I bought a Bosch 4.8 volt cordless screwdriver - made in Switzerland - very basic, just forward and reverse, a handy workshop tool rather than a tradesman's weapon.
It is now on it's third set of four subC NiCd cells - Sanyo SCR1300s.
Mechanicals are still good, so I expect to fit another set some time in the future.
Purchase price in 1996 was A$45.
Four SCR1300s cost me A$14.
FYI:
the charger puts out 560mA and has an electronic timer that cuts it off after 2.5 hours.
Too simple.
.... Phil
I assume, because of the question mark, that that was a question. If a cell in your dustbuster is shorted and the charger is stupid, like the one that comes with a dustbuster, you can melt the wall-wart...or get it hot enough to open the thermal fuse in the transformer, if it has one.
In high charge rate devices, you can overheat the cells or the charger components causing cascading failures.
Many, many consumer devices are designed, and I use that word loosely, to charge a partially discharged battery. The designers don't seem to care about fault conditions and domino failures.
I would have taken pictures of the laptop battery that exploded due to a shorted NiCd, but I managed to get it outside before it exploded and never found the cell.
So, yes, it can matter quite a lot.
I think one of the problems is when the cells become unbalanced. In that case I agree that cycling them individually is much better, but in alot of cases that is impossible or at least impractical.
This correct. In a battery, one or more cells might have less capacity than the others, and will go into reversal before the others have discharged. (I actually once saw this with an alkaline N cell in a HP calculator!)
I use NiMH cells in many devices, and they work fine. The Sony products I have that were designed to recharge nicads have no problem with NiMHs.
The basic rule (at least for power tools) is... Recharge the device at the first sign the voltage is dropping.
Actually it was rhetorical but good answer. The battery is toast but there is always the issue of the elcheapo charger.
I remember most NiCds charge through a resistor to limit the current, at le ast the smaller ones like in cordless phones. However I wouldn't put it pas t them to just let the trsansformer choke on the current to limit it. In th at case yup, the charger could fry.
I thought exploding batteries was a more recent phenomenon, but then again there are more things in heav.... wait heaven has absolutely nothing to do with this,...
You know newer cars are like that now. You can't just stick a completely de ad battery in them because it will fry the alternator. Cheap junk.
There's no such thing as "memory effect" but there are other problems with similar symptoms:
There's no way to "fix" a dead or dying battery. The best you can do is test your batteries. I use a West Mountain Radio CBA-II: Charge the battery as best you can, and run a discharge test. For example, a common NiMH AA battery: The battery capacity, in amp-hrs is the point where the voltage starts to drop. If the battery pack does not meet your expectations, or does something disgusting, either tear it apart and rebuild it, or recycle and replace it.
There is also a wide variety of good (and bad) advice on how to extend your battery life. See the various articles at: under the appropriate chemistry.
I find that the limiting factor to battery life is the charger design, especially the EOC (end-o-charge) detection. Rather than think about how one would extend battery life, think about all the ways one could intentionally destroy a battery with a charger. For example:
I've seen all of these in various devices. The problem is that manufacturers believe consumers are more interested in fast charge times and long run times, than they are in battery life. So, they set the charge controller to as close to 100.0% as possible, and charge to this point as fast as possible. The result is short battery life. Fortunately, some laptop manufacturers now have a setting in the CMOS to allow charging to something less than 100.0% in order to extend battery life.
With Li-Ion, there are problems at both ends of the charge scale. See the chart at: Note that the acceptable range of charge and temperature (green area) is outside of where literally all users and chargers operate Li-Ion batteries. In short, operating a Li-Ion battery solely for long life is difficult, if not impossible. The article continues with other ways to kill Li-Ion batteries.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Strangely, all my Li-ion batteries perform very well. I had a bad Vertex charger that dilled some HT batteries with too much voltage, I discharged them through a resistor to about 5Vdc (2 cell battery) then recharged them in the device, not the drop-in charger. They have been working better than ever since then. My buddy has a 12Vdc Shorai in his Harley, it works way better than the golf cart battery Harley gives you.
I am generally suspicious of urban legends, but that of "nicad memory" goes back at least 50 years. I remember reading (in trade magazines) about rechargeable toothbrushes "losing" their capacity until being run down. I didn't disbelieve it then, and I don't disbelieve it now.
You probably don't remember Motorola's (I think) charger for Honeywell electronic flashes. It used "pulse" charging -- a heavy burst of current, followed by briefly shorting the battery. Bert Keppler reported in "Modern Photography" that it did, indeed, "heal" or "fix" older battery packs with degraded performance.
your battery life. See the various articles at: under the appropriate chemistry.
especially the EOC (end-o-charge) detection. Rather than think about how one would extend battery life, think about all the ways one could intentionally destroy a battery with a charger. For example:
No argument with any of this.
manufacturers believe consumers are more interested in fast charge times and long run times, than they are in battery life. So, they set the charge controller to as close to 100.0% as possible, and charge to this point as fast as possible. The result is short battery life. Fortunately, some laptop manufacturers now have a setting in the CMOS to allow charging to something less than 100.0% in order to extend battery life.
Two points... Some (if not many) li-ion battery packs have their own chargers. (The pack for my PDA does.) This increases the probability the battery will be correctly charged.
When plugged into the charger, my HP notebook won't charge the battery if it's at 95% capacity or higher. It has to discharge below 95% before the charger attempts to top it off.
I think you're misreading the graph. The temperature is in Celsius, not Fahrenheit.
I have had zero problems with the OEM li-ion batteries that came with anything I own. The one in my PDA failed gracefully after seven years (almost to the day), and the third-party replacement is coming up on three years.
Notice I said OEM. The third-party li-ion batteries for my Olympus E-500 and Yaesu handy-talky failed a few weeks after purchase. The original batteries are still working, years later.
N? Sounds like HP41C
- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
One is an Acer Aspire One netbook I didn't touch for two years and now the battery won't charge, but the computer works well with the adapter plugged in.
Then there was this Siemens SX56 smartphone that I replaced the battery on and it charged once, then when it discharged, it refused to turn on or recharge. I had bought it used five years ago and never tried to use it until recently, so I never knew it ever working. I wish I could find an easily identifiable short.
A long time ago I had gotten a used Compaq Aero 4/25 and ev'tho I changed the battery with a new one from Varta three times, it never worked right without being plugged in.
I wonder if there isn't some poor man's trick by putting a resistor in the adaptor jack or something.
- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
Could have been, but in this case it was a 28S.
When I'm not using my HP, I leave it plugged in. If the battery drops below
95%, the charger will bring it up to 95%, and halt.
Pulse charging is still around: I don't have enough experience with pulse charging to have an opinion.
Hmmm... something must be wrong. Nobody ever agrees with me.
Yes, that would be logical, unless the vendor has a financial interest in selling overpriced replacement batteries.
Nice. Laptop battery packs have coulomb counters, that record the SoC (state of charge) of the battery. However, some laptops don't use the SoC information properly. If I charge the battery to full charge, and unplug the charge cable, some laptops will continue charging when the cable is reconnected. I think they will shut off after a few minutes, but I've never bothered to measure this.
Oops, you're correct. Looks like -10 to +90C. That's the temperature range where most users operate the battery.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Depends. Many Lithium chips disconnect permanently when the battery voltage falls below some threshold. Others will recover if you open the pack and charge each cell individually to > 3.5V or so.
Compaq Aero is my example of a BAD design. There's nothing in between the power jack and the battery except a FET. The charge current limit is in the power brick. I made the mistake of charging it from a stiff supply at the "rated" voltage. The FET caught fire and burned a hole in the board.
*+-Could have been, but in this case it was a 28S.
My mom bought me the first HP41C sold in NYC on New Year's Eve 1979 from Bloomingdales. It still runs like a song. When I took finance after engineering school, I programmed a root finder for NPV while my classmates where struggling with log tables. Since I wrote the program myself, I was allowed to use it.
- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
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