The character count limit for a message on WhatsApp Connect is 4096 characters. This limit is imposed by the WhatsApp Business API used for Sending Text Messages as explained here.
Sending a message containing more than 4096 characters will cause the following error (Figure 1):
Figure 1 Error Message
Note: The character count includes the display name and colon, so slightly fewer than 4096 characters are available for a message
Note: Line breaks and items formatted with bold and italics also use up character space