Laptop battery Memory effect

I don't believe NiMH batteries have memory effect. They are only good for a certain number of charges. I suspect that is what has happened in your case. The voltage will read good when charged but the amount of energy stored is small.

"Weinberger Hans snipped-for-privacy@aol.com" This appears to be a controversial subject and yet some NiMh

Google for NiMH memory effect and you'll find all the answers you need (and you don't want to hear).

Meindert

This appears to be a controversial subject and yet some NiMh manufacturers claim that they do exhibit a memory effect. I hear dendrites form in the cells when used for a long time that inhibit proper charge flow. Still don't know how to discharge the things. Have you any ideas?

Hans

The problem is as I mentioned earlier you can hardly get any charge to the cells. The laptop signals when the batteries are being charged ... This happens only for a few minutes as said above . Then charging stops.

Hans

And NiCds only exhibit a 'memory effect' in *very* rare circumstances, mainly in satellite applications.

Leon

Nope. Try

Over time, the NiMH cells will increase in internal resistance, and fail to deliver enough current to the load. What I would do, is to take a .1C load (if 2Ah, 200mA), and discharge until the lowest cell voltage falls below 1.1V. (MONITORING EACH CELL!)

This can in some circumstances, if done repeately, then charged, have a small to medium effect on charge life.

That's hardly an authorative source. I'd rather go by what battery manufacturers say, in their literature.

Leon

The author is the founder of Cadex a world leader in the design and manufacture of battery analyzers and chargers, but if you believe more in Battery manufacturers I'll give you 1 example, Sanyo a manufacturer of Laptop NiMh cells It says the Memory effect exists in NiMh cells over here

Hans

I think they have it wrong, they are talking about ''voltage depression' which is a totally different phenomenon. As I said, true memory effect only occurs in very rare circumstances.

Leon

LMAO . First a founder of a worldwide leading Battery charger /analyzer company is considered dumb by you, now Sanyo Corporation do not understand what the memory effect is.

Thats actually bad quality trolling.

exskimos

Dendrites were mentioned earlier. They usually cause a discharge resistance that slowly draws more current over time. This usually happens in an uneven way in separate cells, causing some cells to be normally charged, while others almost fail to charge, and quickly discharge. Delta peak load termination dismally fails in this case. Or the temp shutoff terminates the charge, or the battery management system senses something wrong.

This internal discharge phenomenon is widely misinterpreted as "memory effect", while it is just an "end of life" effect. A well used battery pack may be worn out after roughly 2 years, while some survive much longer - all it takes is one cell to go bad prematurely.

Unloaded the cells may show normal voltages (per cell) directly after charging. Charge it - check after a few hours and see what's left. Some cells will still do OK, others may be deflated considerably.

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Be careful, you could loose what goes for your head!

You being the Troll boy ... you disagree with what "Leon" wrote; why misquote it also? To appear more stoopid??

Yersee:

Normal People do not care about exotix like the mythical "memory effect" enough to discuss it, they just buy a NEW battery pack and SOLVE the actual problem - presumed to be "the computer not working without the charger" instead of running around trying to pick an argument, which is what Trolls do.

Batteries wear out; but, by all means, *do* tinker with the batteries and fry your laptop (preferably when it is actually sitting on your lap to the benefit of the gene pool)!

stoopid??

woul

This is what Saft says:

Do nickel-cadmium batteries for telecoms exhibit the memory effect ?

The memory effect is a reduction in capacity of a Ni-Cd battery, which occurs after the battery has been subjected to repeated shallow discharges. Memory was an issue only with the first generation of sealed Ni-Cd cells, and relates to the way in which they are charged. Telecom Ni-Cd batteries are comprised of vented or flooded cells which do not exhibit memory effect. "The so-called memory effect has been a problem with nickel-cadmium batteries in some applications. Pocket, fiber and plastic-bonded plate cells do not show this tendancy."

Here is a good description I found of voltage depression:

Ni-Cads have an undesirable characteristic that is caused by constant overcharge and no, or infrequent, discharges, as in standby applications. It is technically known as "voltage depression" and commonly, but erroneously, called "memory effect". This characteristic is only detectable when a full discharge is performed. Thus, it is possible to believe a full charge exists, while in fact it does not.

I'd trust what Saft says; where I used to work we used their batteries exclusively for critical military applications. Sanyo does seem rather confused about the phenomenon.

Leon

"Weinberger Hans snipped-for-privacy@aol.com"

Well - you just suck bum-boy ... and you don't qualify either!

OK I get your problem. Try hitting your head as hard as you can against a wall. If that doesn't work use a hammer on it. If that still doesn't work try writing on alt.drugs.psychedelics . Good luck. Hans

woul

Thanks for the quote. I will send some more interpretations on the subject if you are interested later. As I said earlier the memory effect is a controversial subject , IMO saying that one side is right wheras the other is wrong is sticking ones neck out. Hey everyone has his own viewpoint and a right to judge things based on his own experience, sensations etc.

Hans

Actually there are techniques to prevent / stop memory affect and satellites use them with a vengeance. Memory effect in not so much rare as rather specific conditions, it has happened to me and others i know. Fortunately there is a solution, forcibly deep cycle them.