Is the capacitor placed correctly in the schematic?
It functions like a low pass filter, with a time constant of 100uF*51=tau=0.00051s 
So it will filter out most noise with that is faster than roughly half a millisecond.

Bypass filters are mainly to solve a problem with line impedance to the load. The battery is a relatively low impedance source, so you may not see much noise. If the cables from the battery are short (and low resistance/inductance) then filter caps may not be needed. As a precaution most people include bypass capacitors without doing a load analysis (because properly analyzing a switching load can take more time=money than the capacitors are worth)