[Q] Extended battery for Ace2/S3 mini topic

Hi

I'm having trouble with my Galaxy Ace 2's battery life. I googled today and found 4000 mAh with back cover http://www.ebay.co.uk/itm/New-4000mA...-/290957031326 , but didn't found any user reviews.

Also i found this http://www.ebay.co.uk/itm/2800mAh-Hi...-/151537348944 and i like it more (because it uses original back cover)

Anyone has experience with this or something similar?
Does it have power for a long time or loose it after month of usage?

Thanks in advance
Soko


Edit: if this is wrong section, i would ask moderators to move thread