Batch editor works fine on 50 or 100, but if I try to edit more than that it fails?The amount the batch editor can edit at a given time will be based on what your server/hosting can support. If all you can edit is 100 at a time then that is the limitation at which you will have to work with. There can be any number of settings or combination of settings on the server/hosting that can affect how much the batch editor can do at a time.
One of many settings in PHP that can greatly affect the amount you can edit is called max_input_vars. By default this is set to 1000.
You can contact your hosting provider and see if they can increase that for you to say around 10000 or so (or what ever you need). This may (or may not) help you but usually this setting is enough to allow better batch editing abilities.