Dormitory socket voltage is very low can only charge desk lamp, what method can be used to charge mobile phone ah?

Before can charge the mobile phone, this time can not be charged, but the lamp can be used, the mobile phone charger is good, can not be charged, that is, the mobile phone is broken, the charging cable may be broken, the jack may be broken, the motherboard may be broken, the battery may be broken, all cause no charging. Of course, there may be bad charger eyes can not be charged.