The one I used.
This was the battery I have been using with great results: http://cgi.ebay.com/ws/eBayISAPI.dll...:eek:C:US:3160
I had to mod the case at top of battery so it would close with Dremel, but with GPS on and not making or receiving any calls phone had power for over 3 days.
Even if I make loads of calls and use many apps, I still have battery left at bedtime to place on charger...
Google, give us back our SD card storage...
Atrix HD Philz 6.0, Vanilla Cyanogenmod 11 JBL Nightly and a 4000mAh battery mod.
Alternate phone Atrix 2 for my son pure stock.