FYI, the Air India list of banned/allowed items is out of date, do not rely on it.

Loose batteries are no longer prohibited according to the latest docs on the Bureau of Civil Aviation Security site (https://bcasindia.gov.in/#!/air_travel). According to that list, the only batteries that are banned are 'spillable', presumably lead acid.

They used to be banned but I haven't had any confiscated for years. They do seem to be 'spotting' and doing more secondary inspections of batteries recently because of their obsession with confiscating ecigs, but they wave loose aa/aaa's through.

Loose lithium ion cells in your carry on can be trickier because of the aforementioned obsession with ecigs. If they see loose 18650 or 21700 cells in your carry on, expect them to do an exhaustive search for the ecig they assume you must also be carrying. I've found it easiest to carry those kinds of batteries installed in a cheap aliexpress flashlight or . Loose lithium ion cells in your checked in luggage are prohibited, but you already know that.

You should bookmark the BCAS list on your phone and argue the confiscation with a supervisor the next time. I've found the airport CISF staff to be among the least prickly of Indian security forces (more like the Army and not the Police) and open to debate. No Hindi required, most of the officers & some constables speak English.