Is there any way we can measure the voltage of such a high mag.( compared to 5V :)) with a very large current be measured on the arduino?
The current can be measured using the next gen.. Allergo ACS715 Automotive grade hall sensor IC ..
But what about the voltage?
Will Voltage divider be safe at this voltage?
I need to for a project...
As long as the output is less then 5 volt there should be no problem. I don't know which battery you'll be measuring, but the voltage may get higher as the rated value. It may be wise to calculate the divider so you can measure up to 55-60 volts.
If you use a voltage divider with resistors, you can use high resistance values.
That way the current can be very low, according to ohm's law.
You have to experiment a bit to find values that give satisfying and stable readings.
If the voltage fluctuates to much (not likely with a battery) and you are afraid to fry your arduino, you can use a zenerdiode to protect the AD port.
A 1M resistor from the analog input to the +48 volt line together with a 100K resistor from the analog input pin to ground will give you a 11:1 voltage divider, giving you a maximum voltage of 55v before the voltage on the analog input pin exceeds 5v. Even if the battery voltage did exceed 55v, the 1M resistor would limit the current to a safe value, so there would be no danger of frying the chip. Current consumption will be about 44 microamps so very little drain on the battery.