Why is my battery life fluctuating? I installed CM7 on my LG P500, and ever since the battery sometimes lasts 30 hours, sometimes for 8 hours, under the same usage and same power state (conservative).  How can I fix this?
I was having that problem, and the solution that helped me was to charge up the battery completely, then use the recovery boot menu to wipe battery stats. Then, I used the phone until the battery died and the phone shut itself off. During that time, it is important to not plug in your phone to USB or charger, it has to drain continuously. Then you can charge it back up again and use it as normal. It should help to make the battery percentage more accurate, and to drop in a more stable way.