Originally Posted by PapaG
I added a 2nd tank and it would last longer with the pressure I wanted, but it did take twice as long to get back up to pressure. So it is always a trade off.
It is a trade off and not a very good one. If a small compressor is trying to fill twice the volume it is designed for it will overheat because it will exceed the duty cycle leading to decreased efficiency, a hot pump will not work as good nor last as long. Since you can not get any more air out of the tanks than the pump puts in any extra run time is just lost to the extra recharge time so you gain nothing, you actually will lose run time due to the loss of efficiency of the overheated pump so it will be more than just a trade off, it will be a losing proposition.