"I wanted to charge the 9 V battery (rechargeable) on a normal 9 V source. The 9 V battery (rechargeable) has 250mA/Hour. Can I charge the battery with a 1A source?"
For charging a battery, the source voltage must always be greater than the voltage of the charged battery to force the current in reverse to the point where the battery reaches the maximum charge and the rated voltage. However, we can never connect the source directly, as it is discharged, there is no limitation for the current and the battery can heat up, even bursting. In the simplest case, connect a resistor in series that limits the current to a safe value for recharging. Normally on batteries, the suggested current for charging is marked. The best thing is to use a constant current source adjusted to the indicated current or less, if we want a slow charge, which is safer.
