Fuseible battery 100am of the megane ´03

Good expert people,

no one knows that happens, nor the official house (which has told me that it is the switchboard) to this renault megane 1.5 dci del´03 that the fuse that carries in the battery of 100am melts every time the car is penetrated or why if it melts, I do not know who to resort to I have gone to electricians to mechanics to another house officials of Renault and nobody knows what happens to him. It is in a semaphor and it melts
is covered by entering with the longest march,
I have given me that putting one se 125am. It will but scheme also melts. Why is it?