title: Random (403) User Rate Limit Exceeded
body: <p>I am using translate API to translate some texts in my page, those texts are large html formated texts, so I had to develop a function that splits these texts into smaller pieces less than 4500 characters (including html tags) to avoid the limit of 5000 characters per request, also I had to modify the Google PHP API to allow send requests via POST.</p>
  
  <p>I have enabled the paid version of the api in Goole Developers Console, and changed the total quota to 50M of characters per day and 500 requests/second/urser.</p>
  
  <p>Now I am translating the whole database of texts with a script, it works fine but at some random points I revive the error "(403) User Rate Limit Exceeded", and I have to wait some minutes to re-run the script because when reached the error the api is returning the same error over and over until I wait some time.</p>
  
  <p>I don't know why it keeps returning the error if I don't pass the number of requests, it's like it has some kind of maximum chaaracters per each interval of time or something...</p>