[General Topics] [[[zen]]]:
think that this article owes interesser many people . ---

Translate with a prog : ( sorry my english= 0 .... :oops: ! )

For your batteries, the solution is there:

Perso, I have a sound which informed me as soon as there remains 25%, then I charge partially. ---

To optimize the lifespan of the batteries

When to reload the batteries? Should a complete discharge be awaited? Does a complete discharge have for effect "to restore", or "to repair", a battery which would lose in autonomy?

The answers to these frequent questions depend on the type of battery considered.

- various batteries and accumulators

Let us retain three families of batteries:

- Nor-Cd (Nickel and Cadmium);

- Nor-Mh (Nickel and Metal-Hydride);

- the Lithium-Ion and Lithium-Polymer.

The three are not subjected to the same rules of use and maintenance. The batteries with lithium have one lifespan (often) more reduced but are of a less constraining maintenance. Nor-Cd are most complex to maintain, but propose the longest lifespan (a number of complete cycles), with the proviso of respecting the constraints of use, while Nor-Mh an interval proposes.

- Of the two "ratchet effects"

The batteries Nor-Cd and Nor-Mh are, both, subjected so that one calls, in the majority of the situations wrongly, the ratchet effect. There exists, indeed, two ratchet effects.

The first case, extremely rare, is that in which a battery ' souvient' of the moment (level of load) to which the user is proceeded systematically to a refill. Thus, ' habituée' with being reloaded on this very precise level, the battery can refuse to function beyond: it memorized a threshold. It is a phenomenon far from frequent, with which researchers of NASA were confronted. The commun run of the users will never manage to reload systematically its battery Nor-Cd or Nor-Mh on the same level of discharge, and this with sufficiently of precision to be confronted with this situation.

The second ratchet effect, sometimes qualified "false ratchet effect", is most current. The "false ratchet effect" is defined as "the crystalline material formation causing [ one ] loss of capacity". In other words, it acts of a chemical phenomenon, caused by electric overloads, which involves an apparent loss of endurance of the battery concerned. To avoid it, it is advisable never not to leave a battery in overload and to proceed, punctually (but not systematically) with complete discharges of the battery (see low).

It is important to note that the batteries Nor-Mh are exposed to the ratchet effect as well as Nor-Cd: most recent Nor-Mh had like commercial argument not to be exposed to this nuisance. Actually, the phenomenon is less sensitive for Nor-Mh for a simple reason: they have one lifespan, by nature, shorter, so that the effect of memory appears at the end of ' the life naturelle'.

The batteries Nor-Cd and Nor-Mh, very widespread, must thus be the subject of precise rules of use (which are worth more for Nor-Cd, therefore).

- maintenance of the batteries Nor-Cd and Nor-Mh: myths and realities

It is an extremely widespread commonplace: the idea according to which it is necessary to await a complete discharge of the batteries Nor-Mh or Nor-Cd before proceeding to a refill... This idea is largely false: it is rather advisable to carry out complete discharges in a specific way, but not systematically. Canadian professionals observed that the complete and systematic discharges had harmful effects resulting in a loss of endurance.

If it is not imperative systematically to carry out a complete discharge of the batteries, it can sometimes be necessary to operate major discharges in a specific way, making it possible to fight against the "false ratchet effect", by reversing the chemical reaction described above. It is thus possible "to restore" a battery victim of crystallization... But this method supposes to have an ad hoc material. Why can't one use the electronic instrument profiting from the batteries to discharge these last? For a simple reason...

The majority of the electronic instruments stop functioning since the batteries do not provide any more the good power. However it is exactly what occurs with a battery victim of the false ratchet effect: the crystallized part does not make it possible to obtain a voltage as important as the intact part. There is thus a fall of tension. Indeed, if the battery could provide 1,2v when it was intact, as soon as it will reach the threshold from which nickel ' cristallisé' enters in action, the current is lower (for example with 1,02v). The electronic instrument will immediately cease functioning, giving the illusion that the battery lost in capacity; actually, the battery is able always to function. Many users replace the battery in load then, longer than usually: the phenomenon of crystallization worsens, and the battery is less and less powerful.

The solution then consists in discharging the battery completely... But that cannot be done with the electronic instrument, since this one stops functioning since the battery does not deliver sufficiently any more of electric tension. It is, so imperative to use an electronic equipment of discharge and to strictly control this discharge: one speaks then about major discharge.

- the tidal wave Lithium-Ion and Lithium-Ion-Polymer

Since a few tens of month, the batteries Lithium-Ion, before used almost exclusively on the portable computers, made their appearance on electronic instruments of very reduced format: Mobile PDA and telephones in particular. The iPod also has a battery Lion-Ion-Polymer.

These batteries have the advantage of not being subjected to "the ratchet effect" of the fact, in particular, of the best held of lithium vis-a-vis with the problem of crystallization; the user is thus freed from the traditional rules: it is indeed useless (even bad) to carry out periodic major discharges. However, the overloads, if they are theoretically less dangerous, are to be avoided. In fact, it is preferable to proceed to short daily loads of a few minutes, and this so as to reduce the number of complete cycles of refill.

Let us conclude on wisdom from the Support service from Handspring: "to frequently proceed to partial loads the optimal effectiveness of any aircraft equipped with a battery lithium-ion ensures."

That it is said!

See the excellent sites:

- the site www.Ni-Cd.net

- the site of the Buchmann Canadians and their file on the batteries (in English with a French introduction)