ICOM M31 update

[Ships_Cat]

I really don't want to continue the "memory effect" argument because it is fuel for flaming and the battery technologists are all pretty much agreed it does not exist. I do not think I disagree with Nigel too much except for his (infrequent) use of the term "memory effect" - what he says is in the main good charging advice

However, the characteristics you find with your own phone battery are likely to be typical end of life ones unrelated to memory effect. Other battery technologies also show the same end of life behaviour.

I have not looked much at cell phone battery usage but one thing that does strike me as a problem for their life is that they are frequently driven in use to complete discharge - that is the phone is driven into complete discharge in an uncontrolled way.

Now that will stimulate another flush of posts myth generating posts I guess.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[Ships_Cat]

It strikes me that most are getting confused between memory effect and other problems with batteries. Memory Effect is the irrecoverable loss of capacity through repeated cycling to an undischarged state (usually to the same point of discharge rather than to random point) and then recharging. There is no evidence that random incomplete discharges of NiCds (and with modern NiCds even repetively to the same point of discharge) results in memory effect and permanent damage to the battery/cell.

No battery technology is perfect and may suffer deterioration through things such as improper charging, extended periods of no use without maintenance charging (lead/acid is a common example), cycling to full discharge (again lead/acid is a good example), etc, etc.

Many battery technologies when they suffer deterioration through causes such as the above, or just through age respond to "conditioning" of some sort. For NiCds this may through an extended charge period, a deep discharge (but never to complete discharge) or in some instances a controlled high rate charge.

A common example of "conditioning" that most have some familiarity with is the equalisation of lead/acid batteries which may slow the development of or alleviate existing sulphation on the plates - indeed it may bring what appears to be a completely dead battery back to life for a time.

But we don't call any of these things "memory effect", although I have to say that I have heard people state that lead/acid batteries suffer memory effect because equalisation may recover capacity, but I hope we are all clear here that is not correct.

Memory effect is a tantilising concept to align ones views with as it has a mystic intrigue about it and some will never consider that it may not exist or that their observations are actually symptoms of other faults. If I interpret Nigel's comments correctly, I think he says that perhaps "memory effect" is a misapplied term for some of the things he described. If I have interpreted him incorrectly, I think that Nigel is well aware from other posts that I regard his views seriously.

I have had a browse through material I have here and have found a very good easy to read article from QST Dec01 by a professional power systems designer in aerospace, etc explaining small battery technologies, their characteristics, strengths, weaknesses, care, etc. If anyone has an open minded interest (and that probably includes anyone who has read this far without already firing up their keyboard in enflamed response) I would be happy to email a pdf of it to them (please PM me). In the article he does guardedly refer to the development of "memory" (voltage depression) in a number of technologies including NiCd and NiMH (which he states shows it less often than NiCds because their life is shorter than NiCds) but is at pains to point out that here he is referring to crystallisation of the nickel plate and that that is a completely reversable (discharge, but not to completion, and then recharge), not irreversable, process.

I will have no more to say on the matter, after all this is a tiresome business for a cat who should be spending 80% of its time sleeping in the sun. In the end it, of course, does not matter to me what batteries people use. However, hopefully a few with open minds will be encouraged to look a bit further for professional well informed information, draw their own conclusions and be better able to understand their batteries behaviours.

John


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[chas]

Thanks all - I will not leave my hand held on permanent charge. I seem to remember in the old days of diesel electric submarines that they used to cycle their batteries, presumably to rid them of 'memory effect'

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[tugboat]

Thanks for your input to this thread. I appreciate it as I am sure do others. Your words have been read and inwardly digested. You have earned a zizz in the sun - shame we can't email you a sardine. /forums/images/icons/laugh.gif Cheers, Tugboat.

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[Ships_Cat]

Thanks Tugboat - I will shout myself a sardine then /forums/images/icons/smile.gif.

Regards

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[John_Clarke]

This seems to discharge the dry cells in about 5 weeks. I have found that all you need to do to prevent this is to undo the battery pack retaining screw and this will disconnect the battery. The battery pack can remain in the radio and the seal remains in its seat so it is probably still rain proof.

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[rmcm]

Firstly, NiCd's should NEVER be shorted as someone suggested earlier in the thread, they should be discharged to a minimum of 0.8v if required.

Secondly the memory effect is a myth

Thirdly, check out http://www.rcbatteryclinic.com/



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[Guest]

The battery manufacturers themselves

They are the ones who supported the findings of various groups such as Radio Modellers etc. about the capacity of NiCD's being subject to reduction due to bad or partial charge / discharge.
The term 'memory' was put about by those involved as the simplest term to describe the effect .... as it resembles the battery 'remembering' the points of charge / discharge over successive cycles - causing a 'memory' and loss of capacity / use of the battery till cycled properly and efficiently a number of times to restore somewhat near to original ...... it is NOT an end of life characteristic - it is an indication of poor charge management and behaviour of NiCD's under such conditions.

Fundamentally Ship's Cat and I agree on near 95% - but totally diasgree on the 'memory matter' - both claiming that experts support respective cases. I can only say that I have never read or seen a report by 'expert' that states 'memory' does not happen ....

Further that I have enough cells collected over years that certainly have this characteristic and have been cycled to remove it till they have actually failed to recover - still exhibiting the reduced delivery .......



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[Guest]

One last PURR .... ?

Pudy tat ..... I would like to offer one correction to a part of your post that may clear away our main - difference :-

Memory effect - the reduction of usable capacity of NiCD's in its early and often repeated incidents IS reversible to a level near to original ...... it is only after repeated occurrence of the maldy that it fails to recove and is then irreversible.

You have a 'violent' and one time remedy for a seriously depressed NiCD - that is to short it with a fully charged 'brother' - which as I have been informed by a former friend who worked at Mallory Duracell - basically breaks up the crystaline structure - which I mentioned previously ..... But it is a drastic and one-time only remedy that often only gives a temporary reprieve ......... final failure of the cell being not too long in the future ! It is claimed by some battery suppliers that repeated full discharge / charge cycles after such drastic treatment restores such batterys to full health - that was disputed by the Mallory guy and also by my experience over many years of RC battery packs in models and radios ....

I think pudy tat and I are on similar wave-length apart from divergence on this memory matter .... and what it eally means !!

So ..... WOOF WOOF !!!

OH ...... Q - how do you make a cat bark ?

A- Pour petrol over it and throw a match at it - WOOF !


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[halcyon]

Re: The battery manufacturers themselves

Memory is not confined to NiCads, back in the 1980's it was a problem when Westerly started using Delco Freedom sealed batteries.
At the time we were supplying Westerly with switch gear/split charging systems, and we started getting bad charging results, were the battery was showing surface charge/low capacity. It turned out that if a Delco Freedom battery was left half discharged over winter, it assumed that capacity, ie a 100 amp hr battery became a 50 amp hr. We advised owners to remove batteries and have them bench charged, it was then possible to leave it over winter without any loss. They also have a different charging curve, but thats another issue.
Afraid memory is not new, and does exsist.

Brian

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[Ships_Cat]

Re: The battery manufacturers themselves

Hi Halycon

The term "memory" is sometimes loosely applied to general service deteriorations of a battery affecting capacity but all batteries are subject to such deteriorations. In the case of lead/acid usually due to sulphation (as I know you very well know) and in the case of BOTH NiCd and NiMH to nickel anode crystalisation and is correctly called voltage depression. In the case of NiCd (and I believe NiMH) this process is reversable (usually by a deep discharge and charge cycle, but as several have now pointed out, never to complete discharge). But as we all know sulphation is only partially reversable, and as in the case you mention it will never be reversed because of the age hardening of the lead sulphate formed in the plates.

It is very easy to sulphate lead acid batteries but it is quite difficult to cause anode crystallisation on NiCds and NiMH's.

All batteries suffer from capacity loss from aging or incorrect maintenance and that is not a problem that NiCds have on their own. The memory effect that it seems 90% of the world is frightened of with NiCds is that where they believe that cycling to incomplete discharge will cause a permanent loss of capacity - this is the myth, it does not happen. The voltage depression that can occur with NiCd's can, as pointed out, also occur with NiMH, however it is less frequently observed with NiMH only because their charge cycle lifetime is very much shorter than NiCd's ie NiMH's tend to get dumped for end of life reasons before it occurs.

Perhaps I can elaborate on other battery types such as NiMH and Li-Ion which it seems many think are far superior in every respect. I think I earlier pointed out the fewer charge cycles for NiMH but the advantage in energy storage per weight (and that is a performance advantage in many portable instances). Li-Ion also has its problems but are rapidly being bettered with development. Both NiMH and Li-Ion can suffer problems which affect their capacity. However, in the case of handheld transceivers (which was what this thread started out about) NiCds have alot going for them in that they have the best high current delivering ability for transmit demands - despite what many seem to think, they are also very reliable. Li-Ion is the best challenger but they still expensive and are susceptible to charge abuse. I don't know about the current crop, but at least until recently Li-Ion batteries had charge managing mechanisms built into them - perhaps accounting for some of their high cost.

John

(Another sardine please /forums/images/icons/smile.gif and I am off to deep cycle my submarine's batteries in case of "memory effect")

<hr width=100% size=1>I am the cat but I am only 6.