My iPhone 4 charging only from Power Bank.
My iPhone 4 was taking proper charge from a 2.1A Tech&Go! charger & original cable for about a year. When it stopped taking charge I tried with original iPhone charger-it failed. Tried with power banks-it failed. But it works only in one way: Discharge the phone fully->connect to power bank-> the phone charges to 100%. But during the process if the phone is moved it stops to take charge. No other permutation combinations will start charging phone again, not from original charger as well. The phone has to discharge and switch off automatically to start charge from power bank again. Whenever phone is charged, whether 1% or 100%, from power bank, all other functions work perfectly and the battery gives its expected backup. Do you suspect Power Management chip?