I want to test my circuit which is powered with 12V, 200Ah battery(VRLA) and check the outputs on oscilloscope. While testing can I connect battery -ve to the oscilloscope ground?
Is there any safety risk, as oscilloscope internally connected to safety earth(PE)? If I connect to battery's negative terminal, it will be connected to earth. Will it cause any hazard?Will there is accidental chance of short .
You should use appropriate scope probe (voltage divider) let say x10. Ground goes to battery negative.
Just pay attention what you connect to battery, because if there is small resistance or short circuit, battery, specially big battery like that can deliver lots of amperage for short time. 200Ah (if starter type) can deliver over 1000A in one moment.
Assuming that 1) The battery -ve is the ground line of your circuit and 2) There's no connection with mains AC power, then there shouldn't be any problem.
We can be more certain if you give details of your circuit, preferably with a circuit diagram.