Getting Error 400 When Calling An Https Request To Apply A Charge On Stripe API

I am using nodejs without any library/npm to make a charge on stripe using the test api key.

However I am always getting 400 status code response, and can't understand why, can someone give me an hint?

Here is my request details:

{ protocol: 'https:',
  hostname: 'api.stripe.com',
  method: 'POST',
  path: 'v1/charges',
  timeout: 5000,
  headers:
   { 'Content-Type': 'application/x-www-form-urlencoded',
     'Content-Length': 72 },
  auth: 'sk_test_JOXtNqPjvpFgLXMiwuWWKZxu:' }

And here is my payload (using querystring.stringify):

amount=5000&currency=usd&description=Tiago_1541865841578&source=tok_amex

Thank you in advance for any help!

Here is the code, the method where I do the request it self:

helpers.sendRequest = function(protocol, port, hostname, method, path, timeoutSeconds, contentType, postData){

   // Stringify the payload
   var stringPayload = querystring.stringify(postData);

   // Construct the request
   var requestDetails = {
     'protocol' : protocol+':',
     'hostname' : hostname,
     'method' : method,
     'path' : path,
     'port' : port,
     'auth': ('Bearer ' + Buffer.from(config.stripe.secretApiKeyTest).toString('base64') + ":"),
     'timeout' : timeoutSeconds * 1000,
     'headers' :{
       'Authorization': ('Bearer ' + Buffer.from(config.stripe.secretApiKeyTest).toString('base64') + ":"),
       'teste':'ola',
       "teste2":"ola2",
       'Content-Type':contentType,
       'Content-Length': Buffer.byteLength(stringPayload)
     }
   };

   console.log("Request Details:")
   console.log(requestDetails);
   console.log("Payload:")
   console.log(stringPayload);

   // Instantiate the request object (using either the http or https module)
   var _moduleToUse = protocol == 'http' ? http : https;
   var req = _moduleToUse.request(requestDetails, function(res){
       console.log(res.statusCode);

   });

   // Bind to the error event so it doesn't get thrown
   req.on('error',function(e){
     callback(err, e);
   });

   // Bind to the timeout event
   req.on('timeout',function(){
     callback(true, {'Error': 'The request took much time and got timeout.'})
   });

   // Add the payload
   req.write(stringPayload);

   // End the request
   req.end();
 };

And here is where I call the aux method to send the request:

var stripeRequestObject = {
                            amount: (totalPrice*100),
                            currency: 'usd',
                            description: userData.name+'_'+Date.now(),
                            source: stripeToken,
                        };

                        genericHelper.sendRequest('https',
                          443,
                          'api.stripe.com',
                          'POST',
                          'v1/charges',
                          5,
                          'application/x-www-form-urlencoded',
                          stripeRequestObject);

In the auth you need to add Bearer before the token, that's how you send tokens to API. I tried to do the request on postman and it works, you can use axios or superagent to perform the request in you js file