Care and Feeding of Ni-Cad's

GOOGLE is your friend, a little effort on your part instead of ours :-)

Due to your mistake in that last line of your posting, I'll assume that you're actually using NiMH batteries. Also, please note that the proper abbreviation for Nickel Cadmium is NiCd. You should have picked that up in your reading on the net.

Note the effects of temperature on self-discharge.

Sanyo Eneloop and other low self-discharge NiMH batteries have a very low self discharge rate and will last several months on the shelf.

Just to make things interesting, ALL rechargeable batteries loose about 10% of their capacity almost immediately. If look at any of the NiMH self-discharge curves: you will notice that there is an initial drop in voltage immediately after charging. So, the answer to how long to 10% discharge is a few minutes.

I use a West Mountain Radio battery analyzer: which will also draw a pretty graph while you wait.

Basically, you don't want to run the battery down to zero. So, you put a few diodes in series with the discharge resistor so that the discharge stops at some known voltage. 1.0V per cell seems about right.

Sigh. My short answer is that reconditioning and zapping do not work. However the R/C community seems to think that it extends NiCd battery performance. It doesn't work for NiMH. I haven't any change on the one NiCd battery capacity curve that I ran for before and after zapping, but who am I to argue with the true believers:

Batteries do NOT need to be reconditioned. If you're experiencing failures, short lifetime, limited capacity, and leaks, look at what you're doing during discharge and charge to the batteries. Most likely, you're overcharging or improperly quick charging. If the batteries get hot, it's too late. Mixing old and new batteries, and then charging them in series, is another good way to kill batteries.

The only way to properly test the capacity of a battery is with a battery analyzer. I use:

A few sample curves: that demonstrate that an NiMH battery does require a few charge/discharge cycles before reaching full capacity.

Most of what you're asking can be found at:

I agree with all points. I would just like to add that 'zapping' a NiCd cell destroys any dendrites that may have shorted the electrodes. NiMH cells do not grow dendrites and hence 'zapping' is of no use.

snipped-for-privacy@interquest.com

However, all your questions logically relate to NiCd cells.

However, none of them have simple answers or even one answer.

Most users have given up on NiCds, due to the many problems and switched to NiMH cells.

Ni-MH cells have way more capacity, low self discharge and no issues with "memory effect" or dendrites.

( Dendrites are the problem that high current zapping can sometimes cure - but never for long. )

.... Phil

"Jeff Liebermann = radio ham & pedantic narcissist "

Capacity = **amp-hour capacity** at some given discharge current and specified end voltage

So it is simply the product of expired hours and load current value - until the end voltage is reached.

NiMH or NiCd cells have their highest terminal voltage at the finish of charging, dropping immediately charging stops and dropping again as soon as a load is applied. It then settles to a steady value until it nearing the end voltage.

Self discharge is the loss of measured *capacity* over time (compared to an immediate discharge) NOT loss of terminal voltage.

... Phil

'Expection' is a cool word. I think it should mean something, like the opposite of inspection. I don't know what that would mean though.

Also used in the phrase: " beyond expection " = " beyond expectation ".

Looks like it derives erroneously from the words "except" and "exception".

Got a feeling it may become acceptable English, eventually.

... Phil

In a few cases I had NiMh cells that returned to work properly after zapping. The charger gave an error telling they could not be recharged but after zapping they did recharge. I cannot tell what was the problem, dendrites or not, but zapping nearly always worked both with NiCd and NiMh too, surely not bringing them to a new life but allowing some more charge/discharge cycles.

I think an ESR meter designed for battery testing would help a lot to pair similar batteries for packs and finding nearly dead ones.

Some smart chargers seem to rely on sampling initial terminal voltage to determine whether or not a cell is safe to recharge. If you have access to a current-limited benchtop supply, try setting the voltage limit at 1.6 and the current to 200 mA and giving the cell a charge. If it's recoverable at all, it should come up to the current limit and achieve a terminal voltage over 1.2 V pretty quickly (less than a minute). If so, throw it on the charger and let it do its thing. A "zap" probably has the same result (raising the terminal voltage above the charger's threshold) but this seems like a gentler approach.

Well, at least you spelled my name correctly.

Bullocks cannot be negative. Therefore, there is no need to take the absolute value of your collection of bullocks.

Ummm... It's watt-hours. Basically, the area under the Voltage vs Time curve for a constant current discharge. "Amp hours is how much charge is stored in the battery. Since a battery changes voltage during the discharge, it isn?t a perfect measure of how much energy is stored, for this you would need watt-hours."

Since many batteries have a fairly constant output voltage over their operating range, many vendors and users take the shortcut and specify capacity in amp-hours. That's fine for a rough guess, but if you want a real number, try watt-hours instead, which includes any changes in voltage.

Capacity = Energy ma-hr is not energy.

I don't have a handy graph but if you run a constant current discharge test on a partially discharged NiMH battery, they will not show the same initial drop in terminal voltage. However, you are correct about one thing... it's not a 10% loss. The energy stored in the battery is the area under the voltage-time curve at a constant current discharge. The area under the initial drop in voltage that is lost is considerably less than 10%. My guess(tm) from the graph is about

First the bulls, now the horses. Are you selling fertilizer in your spare time?

IME about 1 to 2 days.

Use the lowest ohm highest power rating you dare until it is cold again.

One failure mode of NiCad batteries is dendrites that short out the cell. The high peak current of car battery blows the dendrite away and the cell returns to normal.

No. Only a discharge test will tell.

Go here for lots of quality information about batteries:

?-)

Some regular ESR meters can test batteries. There were some web pages showing how to make an adapter to isolate the DC from the battery.

He's active in audio. He knows shit from shinola, but his customers do want their irrational prejudices catered to.

their irrational prejudices catered to.

Phil Allison knows his electronics and I have no problem with trusting his opinions and judgment. I've locked horns with him extensively in sc.electronics.repair. He has caught many of my errors and has made far fewer mistakes than me. In this case, I believe that he's wrong, but that's my opinion, and not an easily proven fact. The problem is that batteries seem to reside in a magic cloud, where misinformation, bizarre rituals, magic potions, Boeing 787 fixes, and amazing manufacturers claims, are the norm. Measuring capacity in ma-hrs is an example. It's probably functional for most situations, but isn't really correct. Same with zapping, EDTA, exercising batteries, NiCd memory effect, and battery lifetime extension rituals. All have their supporters, and all are debatable, somewhat dubious, often destructive, and under specific conditions, sometimes actually work.

I've made it a point of trying to convince Phil that it's not necessary to insult the person that he is trying to inform or correct. He's not the only one with this problem, but seems to be the only person that understands that it is a problem. The apparently incurable one-line insults in sci.electronics.design are only slightly better than Phil since there is little profanity or Australian idioms and slang.

As for irrational audiophile prejudices, I wish that I had more audiophile customers. Right now, I have exactly two. Well, one is a videophile, but close enough. They spend amazing amounts of money on hardware and services, which helps support my decadent and lavish lifestyle. I like audiophiles.

I share your high opinion of Phil's technical competence. Batteries are just plain complicated, and what works in one situation isn't guaranteed to work in another - ostensibly similar - situation. People to get addicted to what works for them.

It would be nice if he cut down the insult content - he's bit to indiscriminate for my taste.

Where is Richard Steven Waltz when you really need him? Nobody else was ever in the same class.

As customers, when they buy stuff. When they spend a lot of that useful money on complete rubbish - supplied by other people - they become less attractive.

I'm all for parting fools from their money, and there's nothing to stop you selling audiophiles really good stuff. Peter Baxandall did exactly that, and Quad Electroacoustic did too, at least as long as Peter J. Walker was in charge.

I disagree somewhat. As long as one stays within one particular chemistry or technology, the care and feeding of that particular battery is quite simple, and usually well defined. Where the problems start is when one tries to apply what works for one battery chemistry, to a different chemistry. What works well for one flavor, doesn't work at all for another. I had to re-learn all my assumptions when I moved from NiCd to NiMH, and then do it again when I learned LiIon.

for my taste.

It would be nice if he eliminated the insults. They add nothing and only give a bad impression. He's not the only person doing that. There was some character in rec.radio.amateur.antenna, that would consistently denounce the OP as a complete incompetent, before demonstrating that he was equally lacking in competence. At least Phil usually gets it right.

the same class.

It's Richard S. Walz. He used to live in Santa Cruz. We were both members of several organizations, one of which declared him to be unwelcome. I tend to be rather tolerant of individuals but made the mistake of sending him a few repair customers. He had a few medical conditions which might explain his personality. I lost track of him, maybe 15 years ago.

I see little of that. My few customers are quite wealthy and generally know what they want. My job is not to supply the equipment, but rather to integrate it with other hardware, make it all work together, and clean up the mess left by the installers.

The motivations of those with money are quite different from the GUM (great unwashed masses). They're not interested in performance features or specifications. What they want is to be able to demonstrate to their peers, at parties and gatherings in their home, that they spent more money on their electronics than anyone else. This also applies to automobiles, boats, houses, landscaping, computahs, etc. Preferably, the electronics should be custom, unique, and therefore difficult to duplicate. Style is more important than function. I have yet to see any "complete rubbish" but I have seen astronomical prices paid for cool looking, but average performing, hardware. They're not going to buy $1,500 HDMI cables, but they might buy a $28,000 turntable because it has style:

I'm not familiar with those people or company. I don't consider any of my customers to be fools. They spend their money as they see fit and within the limits of their finances. If they even suspected that I thought them to be foolish, they would immediately find another consultant. I tell them exactly what I think of the equipment, including anything that I consider to be a potential problem. However, that's not what they want to hear from me. They usually have already decided to purchase some device, and they want to know if I can make it work in their home (or office). I have yet to fail, but I've come close.

I've not got the impression that all NiCd's are created equal, and I've not dug into NiMH to have an opinion there.

Him, John Larkin, Jim Thompson etc.

ever > >in the same class.

It was Richard Steven Walz when he used to post here.

He was certainly irascible, but he did produce very high class insults.

That's certainly not your common or garden audiophile, who wil spend a mint on a valve/tube amplifier in part because it looks cool and in part becaus e he likes a bit added extra odd order harmonic distortion in the stuff he listens to.

They were legendary in the UK, and took some trouble to demonstrate that an ything that actually sounded different was making an measurable difference to the signal that went through it. It meant setting up double blind experi ments from time to time to show up the "golden-eared boys".

Sounds interesting, and it's certainly not what is meant by audiophoolery.

You may have you chance next weekend. It's Ham Radio Field Day, where hams world wide give thanks to the radio gods by making a pilgrimage to the nearest mountain top, and transmitting petitions for improved HF propagation to the radio gods for 24 hrs. Unfortunately, it's in April for Australia (mostly due to seasonal weather conditions). which coincides with World Radio Day: You should be able to find a local ham radio group. If they participate in next weekends Field Day, you might consider joining them. It might be like mixing oil and water but I suspect they might be willing to take the risk in trade for you telling them everything that they're doing incorrectly.

"Jeff Liebermann"

( snip pile of Jeff's juvenile drivel )

Fuck off.