YEah but how much air do they push with only 7 volts?
In general, airflow of fans like this varies in proportion to the voltage applied. So does the fan speed. The noise level is a function of the fan speed. The only real difference in these fans is the nominal speed they operate at, at a given voltage.
If you go to the
Panasonic website, you will see information and graphs that tells you that the "H" model runs at 2950 RPM at 12 volts, therefore, at 7 volts, it should be running at about 1720 rpm, which is roughly equivalent to the quiet "L1A" model at 12 volts (1900). So by running this fan at 7 volts, you get just slightly under the performance, and probably slightly quieter operation as well.
If I needed fans, I'd jump on these suckers, because by wiring for 7, or even 5 volts, you still get a VERY quiet fan with decent airflow, but you have the option of running it at higher speeds, unlike the "L1A" model. These would be a great choice for use with a thermistor control, or a rheostat.