my first thought was, when i was holding my new N900 in my hands and looking on the battery status: "i need extra power". my resctrictions were: fast charge and recharge, small form factor and connectors for N900 (micro USB) and N97mini or E71 (2mm). so i found this on Nokia's accessories site:

Nokia Extra Power DC-11

Official Desciption at Nokia:

"Any place, any time - be productive, be entertained and be in touch with the light Nokia Extra Power DC-11. Simultaneously charge the two devices you use the most for calls, messaging, navigation or music. It provides up to one charge for your mobile phone. High-quality materials, a rechargeable battery and excellent cable management make life hassle free when you're on the move."

with the Nokia Extra Power DC-11 you could charge up to 2 devices. if you connect a charger, you could charge the extra pack and the 2 devices simultaneously. i like that you could recharge your phone when you're abroad.

if you've charged the DC-11, you can leave it ca. 2 weeks without recharging it again. to charge the DC-11 you have to connect a extra charger like AC-8  and the white LED will start to flash. it will stop blinking, when its fully charged.

i was able to charge a N900 and a N97mini at the same time, while sitting on the plane heading home.

this gadget works very simple. all you have to do is connect the DC11 with your phone and press the only button. the white LED starts blinking and your phone is charging. when the LED is not blinking, when you press it, then you have to recharge it again :-)

you could "expand" your battery up to 14 hours operating time on N900 (Wifi and 3G on) and up 16 hours to N97mini (Wifi and 3G on). this is very usefull, when you use OVI Maps or listening to music.

there is one little disadvantage:

you need an extra charger with 2mm connector to charge the extra pack, because there is no one included in the package. why does Nokia not built-in a micro USB port for charging it?

Conclusion:

Because of the form factor of the phones and the lack of Nokias batteries, the Nokia DC-11 Extra Pack is a very usefull gadget for recent smartphones. you cannot have enough juice for your precious phone.

Specifications:

• Dimensions: 113mm x 56mm x 11mm (L x W x T)
• Weight: 94 g
• Charging cable length: 113mm
• 2 Charging connectors: Nokia 2.0 mm, micro USB
• Recharging time: ca. 2h 45mins with AC-8 Power charger
• Charging Time: N900 ca. 2:20 h 100% full and N97mini 100% full 2:30h
• Power supply: Rechargeable 1500mAh Li-Ion
• Output: 4.2V, 450mA / 5V, 500mA

Package contents:

•     - Nokia Extra Power DC-11
•     - User guide