"Open account" defined.
The term "open account," as used in this title, means an account, usually retail in nature, under which the creditor permits the customer to make purchases or obtain loans, from time to time, directly from the creditor or indirectly by use of a check or other device as the conditions of the account may provide. The customer has the privilege of paying the balance in full or in installments and an interest charge may be computed by the creditor from time to time on the outstanding unpaid balance and added to that balance. "Open account" does not include those accounts covered in chapter 54-11, or revolving loan accounts authorized by § 51A-12-12.