Care and Feeding of Ni-Cad's

Constant current loads are not very realistic. Most devices these days have switchers, so the load is constant power. But Jeff is right that under a light load, the battery voltage is very flat.

Oh, and Phil sucks kangaroo dick.

A better way is a 12V SLA battery and a headlamp bulb for current limiting - as soon as you can feel the cell warming up, its ready to go in the automated charger. A few jolts might be needed if its got shorting dendrites.

Whichever way you go, temperature is the main thing to watch!

"mike" Phil Allison :

... Phil

"miso"

Plus a total PSYCHO TROLL as well.

Scum like you have no place on earth.

FOAD.

Your reading comprehension is quite poor, probably due to your psych meds. Still you should stay on your meds, even it it does diminish your mental capacity.

Amp hr is a spec. It is easy to replicate in different labs, though you need to agree on a discharge voltage. But watt hours reflects real life thanks to switchers being so prolific these days. So Jeff is correct for real life applications.

When you blow your brains out, do it over grass. The blood eventually washes away. Otherwise the clean up can get costly if you are indoors. I suggest using a hollow point since the bullet doesn't have to go far. That is safer for everyone else.

"miso" = F****IT TROLL

Cos you snip & ignore whatever you don't want to read.

Then you change the context and preach from on high.

Like all AUTISTIC TROLLS do.

Cos they are INCAPABLE of anything better.

Cos they are all mental retards.

F*ck off and DIE soon.

.... Phil

Well, we each have our favorites. I've been unsuccessful with that method. There's just not enough energy to blast the dendrite. Just heats it up slowly and makes things worse. While it's safer than a car battery, I'm not sure it's safer than a controlled energy burst. YMMV

If it is for a single cell: Use a diode in series with a resistor so the cell is only discharged to the voltage drop of the diode (about 0.7V).

"mike"

Try to apply more than 1.8 volts to a functioning NiCd cell and it will draw over 100 amps.

Best zener in the world.

F*ck you.

... Phil

Some people suggest the capacitor-discharge method. 50V IIRC, but I can't remember what value of capacitor.

Frequently I get the error indication (blinking red LED) when I put Ni-Mh cells in the charger - I don't think its dendrites on those. I keep an old iron cored transformer car battery charger to hand, a quick dab with a car indicator bulb to limit the current and all is well.

You seem to have bigger NiCd's than me. And crummier zeners.

No thank you, but thanks for the offer.

Well, I wouldn't use a "raw" 12 V battery. lol.

"Zapping" is to remove the "short." It certainly does work in the sense th at it will recover an otherwise useless cell. Then the cell needs to be ch arged. "Zapping" is merely a transient "high" current sufficient to remove the "short."

"Reconditioning" for NiCd is usually for removing memory or other reduced c apacity effects, and does (sometimes) help NiCd batteries. It involves a f ew deep charge/discharge cycles.

The prevalence of "memory effects" in NiCd's does get debated. It does hap pen, and the deep cycle "conditioning" may help.

For example, a fireman taking a NiCd powered HT out of the charger for repe titive short runs of near duration. It can develop memory effects, or some kind of reduced capacity. Deep cycling can remove the memory effects. It is questionable how many modern NiCd cells have the memory issue. They ce rtainly used to.

In the past I've had excellent results curing memory effects in Ni-Cd cells using pulse charging, a good method is a charge pump running from a loaded SMPSU, at one of the secondaries. Use a Shottky diode for the reverse clamp and a regular fast-soft recovery for the rectifier - the Trr gives narrow pulses of discharge current.

My experiments in this area pretty much tailed off with the decline of Ni-Cd, there seems to be little or no clear advantage from pulse charging Ni-Mh cells.

I'll stand on my comments that zapping does not work, at least for me when I have tried it:

Did you read the article that you cited? Modern NiCd's do not have any problems with memory effect. However, they do have problems with crystal formation on the nickel plate, which produce symptoms similar to memory effect.

That's the standard method of operation. I do much the same thing. I previously posted a typical horror story of the local HEARS (hospital emergency action radio system) network, using Motorola MT2000 handhelds left in the charger 24x7. They would only be removed from their charger for the weekly radio test. After about 9 months, all the NiCd batteries were dead. NiMH batteries were later substituted and they died in about 4 months.

Such battery failures are not always the result of crystal formation. Older NiCd only chargers by Motorola overcharged the battery or failed to properly detect EOC (end of charge) when reinserting a nearly fully charged battery. All it took was a short term power failure, and the charger would start charging as if a discharged battery had been inserted. While it is common to blame the battery for having some manner of memory effect, it is more correctly the fault of the charger for repetitively overcharging the battery, by overcharging due to an excessively aggressive quick charge, or for a too easily fooled EOC detector. Of course, all such overcharging failures are usually deemed the fault of "memory effect".

Incidentally, such chargers don't work well with NiMH battery packs that fit the same charger.

Much as I like Isidor Buchmann, I must point out that the author makes his living selling CADEX battery exercisers and rejuvenators. I would feel a little better if he didn't have a vested interest in selling them. I don't own any such rejuvenators and therefore don't know if they are effective. I do know that slowly discharging each individual cell to about 0.6V does work, but doing the same thing to the entire battery pack at one time, does not work. When I've done the entire pack, with a simple resistor and diode string discharge fixture, I've always ended up with at least one cell getting reverse charged and totally shorted.

I have an experiment going on at my home. My wife and I use the Sonicare tooth brushes, mine is always on the charger except when in use. Hers doesn't get charged until it doesn't work for her. I think it has been over 3 years since we got the new brushes and both are still going fine. I haven't noticed that she uses the charger any more than in the beginning. I don't know what type of battery they use, that I will find out when the battery dies. I will also find out how I should have taken it apart. The second one will come apart much easier.

Mikek

The Sonicare Elite models use one or two 1200 ma-hr NiCd battery. There are also vendors selling a 2150 ma-hr NiMH replacements. No clue what's inside yours. Model number? I don't have a schematic but with a CPU, it's likely to have a coulomb counter chip, which should be adequate to prevent over charging and discharging to zero. If that's the case, both charging methods should last about the same amount of time. However, without a coulomb counter, it will probably be like a typical cordless electric shaver... 3 years and it's dead, no matter what you do.

Incidentally, I was involved in the design of a low power ultrasonic dental scaler (plaque scraper) that used an electric tooth brush as a base. I think it used a Philips Sonicare as a power unit, but I'm not certain.

Okay. It is a natural right of human beings to be wrong. lol. I've done it, successfully, hundreds of times, for the description of zapping, and ca use I've mentioned. A "shorted" cell has no capacity. Zapping it makes ch arge and storage possible.

If you have not had any success, you didn't do it correctly, or didn't have the problem in the first place.

Yes. Did you?

Yeah, and then they go on to say:

"Recondition is only effective on working batteries." That admits the need and effectiveness.

Then, the entire final paragraph is "Results of Battery Maintenance" where they show reconditioning was effective.

I used to work for Santa Cruz County 911 (I left in hmm... '93?). I worked on all the public safety stuff and public works equipment. I installed th e special base station EMS radios at Dominican, Watsonville, and whatever t he name of the other one was before Dominican acquired it. (That system al lowed voice and EKG over a single voice channel.)

In any case, I "zapped" and "reconditioned" more cop/fireman/sewer worker b atteries than I can remember. It was not always successful, but was at tim es.

Yes, I recall complaining to my supervisor about Motorola chargers wrecking batteries. But no, we never blamed "memory effects" in a blind manner. R egardless, a low capacity battery got the same treatment.

atteries

I'd only feel "bad" if it was shown his products were ineffective (a waste of time and money).

That depends on the quality of the pack. By "quality," I mean "cell matchi ng." If cells are not well matched, reconditioning attempts on multi-cell packs is tenuous. I agree on that. My experience is that there certainly w ere quality differences amongst vendors. For example, Motorola packs had a decent recovery rate. Many aftermarket battery replacements... well, not so much. I think many packs are crap regarding matching, so on this point, I understand your negative assessment.

But that is all ancient history for me.

Yeah, poorly matched. They suck.

Interesting. Thanks.