I have a device to measure tilt which is powered by 2 batteries (9 Alkaline Battery, Industrial by Duracell). So essentially, the voltage supply is 18V. I am using it for a project that came with a "black box". This black box has essential has a switch that changes the supply from battery to a supply from mains and a converter to step it down to 18V.
I need to log the tilt measurements for large amounts of time (a few weeks or months even). The mains supply can run forever but it is just too noisy and distorts the data. Digital filtering and smoothing doesn't help as the recovered value is wrong and accuracy is very important. The battery supply is fas less noisy and I am able to get accurate readings, however, the batteries only last about 3 days.
My question is, to provide a stable supply for a long time; would connecting multiple batteries in parallel solve the issue a will there be some shorting if there is a mismatch in voltages.
Is there any other solution (to make it work with batteries)? Smoothing the mains even further?