[QUOTE=Mentalist Traceur;1277118][\QUOTE]

Search for "Charge" and press GO above.

I am talking about regular AA rechargeable batteries that can be charged by regular battery chargers. I used these e.g. in my camera, and the NIKON battery delivered 1200 mAh. I bought new now, that give 2700mAh which is better than Durecell batteries (you know, the ones that power the rabbitt).

Yes, I come apparently from nowhere, but know pretty much about this. You charge a battery by raising the current briefly above the voltage it is about to give, and the difference in voltage varies with battery technologies. A modern battery is like a capacitor, where the charge is held for later use. The capacity is determined by the chemistry and surface - increase the surface or replace the chemicals used between the conductors, and you increase/ decrease the capacity.

Ampere is the measure of current, Voltage the potential and h is 60 minutes. m is short for "milli", so there are 1000 mA in 1A.

If someone produce a battery that can be charged to 4000mA, it will use significantly longer time to charge, and it may need another voltage / current as you see for LiOn betteries. External chargers can work by simply measuring the heat in the battery, and just keep on charging until all the energy is used to heat the battery.

That is the ONLY fact that is relevant to my claim that I don't consider it reasonable to trust a battery manufacturer until their battery has been tested.

Just go ahead and believe what you want. The fact is that the IC that is fitted in the N900 to charge the battery is made for the 1240mA battery, it will stop here. If you buy a battery that claims to be able to be charged above this, you need an external charger. It may measure the heat in the battery, but I seriously doubt that because the battery software provide no indicator of temperature. So a bad battery that can only take 800mA, will get very hot at the end, and a battery that can take more will be charged to 1240mA and stop here.

I bought my battery on Ebay - see the posting earlier. It was expensive, cheaper ones are available, and some offer a separate charger. If you intend to get the battery charged more than 1200mA, you must use an external charger - like the referred Dane. What is said is that he tested numerous batteries and found only minor differences. But now you have new chemistry, cleaner production lines, larger surface, - e.g. use of tiny "holes" to hold electrones. To make these surfaces is very expensive, and pay more you get a larger surface with the "holes" that can be measured in molecules. But also this technology will become cheaper, mono-disperse particles less expensive and available to "regular" use makeing it available to all.