I have Icarus on my phone, My longest go is 41 hours, I believe. I know the best way I've found to reserve battery is to have it underclocked when the screen is off. Also, I use Android Assistant, It easily shows me what apps are running so I can end them if I need to free memory/etc. I also like this app because it's got a start up manager and a cache cleaner (Where you access the cache under each individual app under applications in the menu). I've tried other battery savers on my Optimus M but, I've found I've had more trouble than good come from it. I've not been able to save contacts, Had market trouble, etc. ^.^