YOU SAID:
my phone battery is low
INTO JAPANESE
私の携帯電話のバッテリーが低いです
BACK INTO ENGLISH
My phone battery is low
INTO JAPANESE
携帯電話のバッテリーが少なくなっています
BACK INTO ENGLISH
Your phone's battery is running low
INTO JAPANESE
お使いの携帯電話のバッテリーが不足しています
BACK INTO ENGLISH
Your phone's battery is running low
That didn't even make that much sense in English.