Return battery charge

    CLI Example:

    .. code-block:: bash

        salt '*' apcups.status_charge

def status_charge():
    '''
    Return battery charge

    CLI Example:

    .. code-block:: bash

        salt '*' apcups.status_charge
    '''
    data = status()
    if 'BCHARGE' in data:
        charge = data['BCHARGE'].split()
        if charge[1].lower() == 'percent':
            return float(charge[0])

    return {'Error': 'Load not available.'}