Normal DC as charger

• Yes
• The type of motor and the characteristics of the power supply are required.

3Ph 415 Volt 50 Hz use for water pump so it duty continues when I take reading pump was disconnected

Mechanically disconnecting the pump, and leaving the motor spinning, will mean that the motor draws less current, as it is doing little to no work.

There is far too little information to be able to comment on the normality of this phenomenon. Running a motor disconnected from a mechanical load, for example, is abnormal.

If we consider that your motor is not defective, it sounds like it is designed for intermittent duty. I'm guessing that it is a gear motor with a large gear ratio. Either way, efficiency is very low, possibly because a lot of gear motion resistance.

Even though the answers below are reversed from the order the questions are asked, they are no less easy to correlate.

A motor without load will not need to draw rated current (current which causes motor armature to reach near temperature limit of winding insulation) to reach speed at rated voltage. Voltage => speed; Current => torque; Speed X Torque = Power

AC sources are converted (rectified) to DC before charging batteries, so, of course you can use DC source to charge a battery. Just be careful to not allow current to exceed charging rate of battery being charged.