The phone, purchased nearly six months ago, already had a swollen battery plugged into a switch connected to a solar panel.
Kusum Kashyap, mother of the baby Neha, was not in the room at the time of the explosion.
She rushed in after hearing a loud noise and cries for help from her other daughter Nandini.
The baby had suffered serious burn injuries and died during treatment in the hospital.
Police said no complaint had been lodged so far but it was a case of negligence by the parents.
The father of the child, Suneel Kumar Kashyap, 30, is a labourer and lives in an under-construction house without a power connection. His family uses a solar plate and a battery for lighting and charging mobile phones.