Gaming DSi battery replace

[X7Desu]

Hi everyone, I have a problem.
I bought used DSi in perfect condition, but the battery life is very bad, about 2 hours on backlight level 5 with AK2 and DS game.
Later I bought a battery for replace from DX, but it runs ~2h too.
Then I bought a battery "DragonPRO 1800mAh" from eBay, but it is identic chinese noname, and runs even less.
I used amperemeter to measure DSi power consumption and it says that is about 230 mA (backlight 5, AK2i). If battery runs 2h with this consumption, it's real capacity is about ~500mAh. It is 40% less than DSi original battery 850mAh.
But I can't find any possibility to buy original battery. eBay sells only noname or used, DX too.
It is possible to buy unused original battery? I live in Russia, thus I need a seller that can ship overseas.
Sorry for my bad English and thanks for replies.

Spoiler

 

[hydrocilator]

Did you try the battery rundown with an genuine Nintendo game? It could be the Ak2i sapping power but all noname batteries will not be as good quality as a genuine battery.