Thank all of you, who are participating in this discussion. Most of your suggestions are very helpful. But I still don't know what may happen when I use stronger charger. Will my battery be charging faster than with standard Nokia AC-10E? And will it be "good" for my battery? What is the highest acceptable current programmed in N900 hardware and software?

A charger with a higher amp rating will charge faster and whilst it may not be as good for the battery as a lower amp-age it is not too serious as after all, the n900 battery can be considered a consumable.

As for your last question, the only dangerous variable to worry about is voltage. That is, "highest acceptable current" is not a relevant concept.

Well, actually it will not charge the battery any faster. The charge rate that a device can perform is limited by the electronics of the charging circuit in the device, provided that the charger can supply the required current.

An example;

Let's say that your device has 1500mAh battery and is intrernally rated to charge the battery at maximum C/1, in this case it means that it expects to pull 1500mA from the charger and charge the battery full in one hour.

• Case 1. You have a charger that only can provide 0.9A. The device can only pull what is given, and so the charging takes (1500/900) = 1,7 hours to fill.
• Case 2. You have a 1.5A charger. The device pulls 1500mA and fills the battery in one hour.
• Case 3. You have a charger that can provide 2.0A current. However the device can only pull 1500mA, so the battery still takes an hour to fill.

Quite right, happily acknowledged, thanks.

N900 seems to take around 1A when loading a empty battery. Beefier charger probably will not charge the battery any faster.

Max charging current on N900 is limited to 800 (or 900, can't remember exactly and too lazy to check the kernel code) mA when a wallcharger is connected, so, no matter the maximum current that charger can provide, the battery will not charge any faster. Also, there is a "charging curve" - the charging current depends on the current charge.

In short - there in no gain in getting a charger that can provide higher output current than ac10, besides that it won't get that hot

...and that you can use it with other devices that will take full advantage of its capacity