I left batteries in the DG700 for 2 years, 2 of them 6 corroded. Manufacturer said that the meter has to be recalibrated. I asked why? Because there is a drift of up to 1% caused by pressure sensor. The question is how significant is this amount. Say we have Blower Door air flow 1650 CFM. So 1% = 16.5 CFM or readout will be between 1666 and 1644. Is the difference practically significant?