We have a chat application that runs on MongoDB. For the amount of users that we currently have, it is sufficient to have a 2 node+Arbiter set up during peak hours.

However, during off-peak hours, we would like to turn off the secondary node and the arbiter to save on cloud computing costs.

Is this possible? Simply shutting down the secondary+arbiter makes Mongo unable to elect a new primary and the app fails. 

If the best/only solution is to remove the secondary and arbiter from the replica set, what are the consequences of doing when adding them back on the next peak hours cycle?