add sanity check for full battery level (no 103%)
Based on these commits:
https://github.com/Quarx2k/android_frameworks_base/commit/e8d2b7a167738457066142adc9c7d1bfd09b6902
https://github.com/CyanogenMod/android_frameworks_base/commit/44c99a0910d2d7ff5a3f0c9631f9bddf0eabaeaf