def if_voltage_update(v_cur, v_in, alpha, refrac_counts):
    """Calculate change in cell's voltage based on current and incoming voltage, no decay.
    
    :param v_cur: Current voltages
    :param v_in: Incoming voltages
    :param alpha: Incoming voltage scaling factor
    :param refrac_counts: Number of timesteps left in refractory state for each :class:`Neuron`

    :return: New voltages
    """
    v_delta = alpha * v_in
    non_refrac = refrac_counts == 0
    v_cur += v_delta * non_refrac.to(v_delta.dtype)
    return v_cur
